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Merge pull request #3475 from siscia/fixIntTake
Ensure integer in guards in Enum/Stream.take
2016-02-21 21:33:30 +01:00 · 2015-07-12 17:58:49 +02:00 · 2015-07-12 17:40:16 +02:00 · 2015-06-29 09:56:28 +02:00 · 2015-06-25 18:01:05 +02:00 · 2015-06-25 16:49:30 +02:00
335 changed files with 16010 additions and 6715 deletions
@@ -1,6 +1,6 @@
 /.eunit
 /.release
-/docs
+/doc
 /ebin
 /lib/*/ebin/*
 /lib/*/tmp
@@ -10,5 +10,4 @@
 /lib/elixir/test/ebin
 /rel/elixir
 erl_crash.dump
-.dialyzer_plt
-.dialyzer.base_plt
+.elixir.plt
@@ -7,3 +7,5 @@ notifications:
    - eric.meadows.jonsson@gmail.com
 otp_release:
  - 17.0
+  - 17.1
+  - 17.3
@@ -1,18 +1,306 @@
 # Changelog

-## v0.14.3-dev
+## v1.0.5 (2015-06-29)

 * Enhancements
+  * [Elixir] Support 18.0
+  * [IEx] Rely only on loaded applications for autocompletion on IEx
+  * [Record] Expand attributes and macros in record extractor
+  * [String] `Optimize String.rstrip/1`
+  * [String] `Optimize String.downcase/1`
+  * [String] `Optimize String.upcase/1`

 * Bug fixes
-  * [Kernel] `|>`, `<<<`, `>>>` and `^^^` were made left associative in operator table
-  * [Kernel] `<`, `>`, `<=`, `>=` were given higher precedence than comparison ones (`==`, `!=`, etc) in operator table
+  * [EEx] Ensure blocks do not clobber EEx buffers
+  * [Enum] Ensure `Enum.take/2` does not consume one extra item when halting on the last emittable item
+  * [ExUnit] Fix `StringIO` processes leakage in the `ExUnit.CaptureIO` when there are errors inside the `capture_io` block
+  * [Float] Avoid rounding errors on `Float.parse/1`
+  * [GenEvent] Fix `GenEvent` detection of modules that aren't loaded
+  * [IO] Read 4K blocks instead of lines in `IO.binread/2`. This fixes a bug where CRLF were being ignored and is also going to improve performance
+  * [Logger] Handle `:undefined` arity in `Logger.Translator` (we get :undefined when a temporary worker of a `simple_one_for_one` supervisor crashes)
+  * [Mix] Ensure config is escaped before being injected into escripts. This fixes a bug where escripts failed to build when containing values like maps in config files
+  * [Mix] Ensure we properly underscore acronyms followed by paths, for example, `HTTP.Foo`
+  * [Stream] Ensure `Stream.flat_map/2` does not consume more items than necessary when piped to another `Stream.flat_map/2` that halts in the inner stream
+  * [Version] Fix `to_string` for versions with numeric pre releases

-* Soft deprecations (no warnings emitted)
+## v1.0.4 (2015-04-07)

-* Deprecations
+* Enhancements
+  * [Elixir] Support Erlang 17.5 and 18.0-rc
+  * [Mix] Support "--search PATTERN" in "mix help"
+  * [Mix] Support `:start_permanent` that starts the application as permanent
+  * [Mix] Support `:build_embedded` that compile protocols, avoid symlinks and ensure protocols are loaded on boot
+  * [Mix] Make "mix app.start" public and support "--permanent" and "--temporary" options
+  * [URI] Speed decoding operations
+
+* Bug fixes
+  * [Elixir] Produce clearer error messages for syntax errors before a sigil
+  * [Elixir] Return value when matching on `_` in the last line of a block
+  * [Elixir] Ensure changes in child deps forces the parent to recompile
+  * [Kernel] Fix a bug where `=~/2` returned false when matching on an empty string. The current behaviour was changed to match the behaviour of `String.contains?/2`
+  * [Mix] Store relative paths in erlang manifests
+  * [Mix] Fix httpc proxy option profile for downloading hex and other safe packges
+  * [Mix] Fix missing behaviour warning when compiling Erlang modules
+
+## v1.0.3 (2015-02-12)
+
+* Enhancements
+  * [Elixir] Do not show exported vars warning
+  * [Elixir] Improve error messages when using invalid expressions inside maps
+  * [Elixir] Skip aliases and import warnings when code cannot compile
+  * [IEx] Improve autocompletion for Erlang/Elixir based on loaded applications
+  * [IO] Make `IO.ANSI.Docs` readable on white background
+  * [Mix] Provide clearer error message when updating archives on Windows
+  * [Mix] Don't go through hex.pm API server to install Hex
+
+* Bug fixes
+  * [Elixir] Ensure all Elixir applications work with code upgrades
+  * [Elixir] Don't leave spurious processes and stale data when the parallel compiler fails
+  * [Inspect] Keep original stacktrace on Inspect errors
+  * [IO] Fix `IO.ANSI.Docs` handling of `*`, `**`, `_` where they would be activated in the middle of words
+  * [Logger] Fix logging with `metadata[:function]`
+  * [Mix] Don't show hex update message on mix `local.hex`
+  * [Mix] Ensure tasks are properly underscored and camelized
+  * [Mix] Ensure Mix does not use ANSI escapes on Windows unless ANSI is enabled
+  * [Mix] Only shutdown Logger if the Mix application is being actually started
+  * [Mix] Ensure priv/include are copied on Windows even if source did not change
+  * [Mix] Ensure rebar dependencies work when user path has a space on Windows
+  * [Regex] Fix `Regex.replace/4` failures when the number of substitutions in pattern is more than the number of matches and support `\g{...}` patterns
+  * [String] Fix LFCR being treated as a grapheme instead of CRLF
+  * [URI] Do more strict matching on URI schema
+
+## v1.0.2 (2014-10-21)
+
+* Bug fixes
+  * [EEx] Remove invalid warning when attempting to inline code in EEx
+  * [EEx] Unify syntax errors to always include `file:line:`
+  * [IEx] Set null prompt function in dumb term mode
+  * [Kernel] Do not define an ets table with the same name as the module as it clashes with user code
+  * [Kernel] Fail compiling try expressions if they lack one of catch/after/rescue/else clauses
+  * [Kernel] Improve error messages when parsing fails on aliases
+  * [Kernel] Improve warnings coming from compile-time evaluation of arguments
+  * [String] Fix `String.replace/4` typespec
+
+## v1.0.1 (2014-10-07)
+
+* Enhancements
+  * [Mix] Add MIX_ENV output to archive.build (as on escript.build)
+
+* Bug fixes
+  * [CLI] Fix Elixir CLI when running on Cygwin
+  * [ExUnit] Include stacktraces in ExUnit timeouts
+  * [Mix] Load dependencies before `deps.check` compiles dependencies
+  * [Mix] Ensure `Mix.Config` is deep merged
+  * [Mix] Change version requirement in new apps to `~> MAJOR.MINOR`
+  * [Mix] Report correct location if `local.hex` fails and give higher priority to powershell install on Windows
+  * [Mix] Ensure `--elixirc-paths` option for `compile.elixir` is a subset of the project `:elixirc_paths` configuration and it does not remove skipped entries from the manifest
+  * [Mix] Ensure `compile.elixir` writes to manifest when files are removed
+  * [Mix] Ensure `compile.elixir` purges and deletes modules before compiling
+  * [Mix] Do not crash on malformed proxy env var
+  * [Stream] Ensure `chunk/4` works correctly when halted
+  * [System] Do not allow relative paths in `System.cmd/3` as documented
+  * [System] Fix `:stderr_to_stdout` option in `System.cmd/3`
+
+## v1.0.0 (2014-09-10)
+
+* Enhancements
+  * [Logger] Add `Logger.enable/1` and `Logger.disable/1`

 * Backwards incompatible changes
+  * [GenEvent] No longer support `{:swap_handler, ...}` as callback return value
+  * [List] `List.unzip/2` was removed
+
+## v1.0.0-rc2 (2014-09-07)
+
+* Enhancements
+  * [ExUnit] Print process mailbox on failing `assert_receive`
+  * [ExUnit] Tag all doctests with the `:doctest` tag
+  * [Kernel] Friendlier `unquote_splicing` error on inline quote
+  * [Kernel] Add `<~`, `~>`, `<<~`, `~>>`, `<~>`, `<|>` as operators
+  * [Mix] `mix deps.unlock` warns when given a missing dependency
+  * [Mix] Fetch hex using HTTPS
+
+* Bug fixes
+  * [File] Ensure `File.cwd` generates lowercase drive letters on Windows
+  * [GenEvent] Ensure the event manager does not crash on `:sys.replace_state/3`
+  * [GenEvent] Do not consider swap handlers to be failures in a stream
+  * [Logger] Fix `Logger.log/2` not to raise on Logger exit
+  * [Logger] Recompute sync/async mode on Logger configuration
+  * [System] Ensure `System.cwd` generates lowercase drive letters on Windows
+
+* Deprecations
+  * [GenEvent] The `:monitor` option in `add_handler/4` and `swap_handler/6` is deprecated in favor of `add_mon_handler/3` and `swap_mon_handler/5`
+
+* Backwards incompatible changes
+  * [Supervisor] Make `max_restarts` default to 3 (closer to upcoming Erlang defaults)
+
+## v1.0.0-rc1 (2014-08-30)
+
+* Enhancements
+  * [ExUnit] Add timeouts to tests (which is configurable via tags)
+  * [GenEvent] Add support for `GenEvent.ack_notify/2`
+  * [GenEvent] Add support for monitored handlers to `GenEvent.add_handler/4` that removes the drawbacks in the previous linked handlers
+  * [Logger] Allow any value that implements `String.Chars` to be logger
+  * [Logger] Allow `Logger.log/3` timeout to be configured
+  * [Mix] Add `--force` option to `mix local.rebar`
+  * [Mix] Fix `--no-color`/`--color` option for `mix test`
+  * [Mix] Add a `:language` option to improve the usability of Erlang projects using Mix
+  * [Mix] Accept wildcards on `Mix.Config.import_config/1`
+  * [Mix] Support protocol consolidation on escripts
+
+* Bug fixes
+  * [IEx] Do not print the underlying type for `@opaque` in the `t` helper
+  * [GenEvent] Do not allow a handler to be added more than once
+  * [GenServer] Do not treat bad arguments as exits in `GenServer.call/2`
+  * [GenServer] Do not deliver out of order messages on `GenServer.cast/2` on distributed mode
+  * [Mix] Do not pre-compile a Mix project if an alias was found
+  * [Mix] Properly handle compilation errors in the Erlang compiler
+  * [Mix] Always try to compile project if task cannot be found
+  * [Mix] Purge in memory modules before consolidating
+  * [Mix] Always compile a project if a task cannot be found
+
+* Deprecations
+  * [Collectable] Deprecate `Collectable.empty/1` and `Enum.traverse/2`
+  * [Integer] `odd?/1` and `even?/1` are deprecated in favor of `is_odd/1` and `is_even/1`
+  * [Kernel] `nil?/1` is deprecated in favor of `is_nil/1`
+  * [Kernel] `x.Alias` is deprecated in favor of an explicit `Module.concat/2`
+  * [Record] `record?/1` and `record?/2` are deprecated in favor of `is_record/1` and `is_record/2`
+  * [Stream] Returning `{item, acc} | nil` from `Stream.resource/2` is deprecated, instead return `{[item], acc} | {:halt, acc}` (similar to `Stream.transform/3`)
+
+* Backwards incompatible changes
+  * [GenEvent] `GenEvent.cancel_stream/1` no longer is
+  * [GenEvent] The `:mode` and `:duration` options are deprecated and no longer supported in `GenEvent.stream/2` (the mode is now a property of the sender)
+  * [GenEvent] The `:linked` option is deprecated and no longer supported in `GenEvent.add_handler/4` (check monitored handlers instead)
+
+## v0.15.1 (2014-08-10)
+
+* Enhancements
+  * [GenEvent] Support `:ack` mode for GenEvent streams
+  * [Inspect] Support `:base` option in `inspect/2` to choose the base (`:binary`, `:octal`, `:decimal` or `:hex`) numbers a printed
+  * [kernel] Print warnings when used ? with characters with escape codes
+  * [Logger] Add SASL log forwarding option to Logger
+  * [Logger] Add `$padlevel` to option Logger formatter
+  * [Logger] Backends receive the exact handler value when added, allowing a key to be passed for configuration lookup
+  * [Logger] Add `Logger.flush/0` to flush the Logger (useful for testing)
+  * [Logger] Persist backends dynamically added or removed via `add_backend/2` and `remove_backend/2`
+  * [Macro] Add `Macro.validate/1` to recursively check if a value is a valid quoted expression
+  * [Mix] Load mix deps only when there is a need to use them (this improves the timing for the majority of tasks in a Mix project)
+  * [Mix] Make the environment explicit on the success message generated after `escript.build` is invoked
+  * [Mix] Load `config/config.exs` inside escripts
+  * [Mix] Store and check Elixir version requirement for generated archives
+
+* Bug fixes
+  * [CLI] Fix shell bugs when running on Windows with Cygwin or MinGW
+  * [Kernel] Modules compiled by Elixir now report the correct beam location when `:code.which/1` is invoked. If the bytecode is only available in memory, `:code.which/1` returns `:in_memory`
+  * [Kernel] Do not expand args for unknown functions/macros
+  * [Kernel] Ensure `defstruct`, `@attr` inside and friends raise a nice error messages when values cannot be properly escaped
+  * [Kernel] Do not raise conflicts on imports used from inside quotes
+  * [Logger] Metadata is now correctly merged on each `Logger.metadata/1` call
+  * [Logger] Use the Logger PID on `:error_logger` wrapper to avoid race conditions on shutdown
+  * [Macro] Ensure bitstrings work with `Macro.escape/1`
+  * [Mix] Ensure aliases are invoked on umbrella recursive tasks
+  * [Mix] Leave it up to the application to start the Logger after compilation
+  * [Mix] Accept more forms of git versions (like "git version 1.9.3 (Apple Git-50)")
+  * [Path] Do not normalize paths in `Path.join/2` as normalization is beyond the scope of such function
+  * [URI] `to_string/1` now properly converts URI to strings when the schema is missing
+
+* Deprecations
+  * [Collectable] Having a function as collectable is deprecated
+  * [Module] `Module.function/3` is deprecated, please use `:erlang.make_fun/3` instead
+
+## v0.15.0 (2014-08-02)
+
+* Enhancements
+  * [Agent] Improve the Agent API to also accept functions that receive explicit module, function and arguments
+  * [IEx] Support `--werl` call on Windows
+  * [Logger] Add `Logger`
+  * [Map] Add `Map.from_struct/1`
+  * [Mix] Allow `--app` flag to be passed to `mix new`
+  * [Mix] Support lowercase `http(s)_proxy` environment variables
+  * [Mix] Allow `elixirc_paths` to also be given through the command line to `mix compile.elixir`
+  * [String] `String.slice/2` and `String.slice/3` have been optimized
+
+* Bug fixes
+  * [IEx] Ensure functions in `Kernel.SpecialForms` and `IEx.Helpers` are also auto-completed
+  * [IEx] Ensure remote shells can be started with `--remsh`
+  * [Kernel] Correctly parse unary/binary operators regardless of number of spaces
+  * [Kernel] Ensure private functions are not exported
+  * [Protocol] Do not expose protocol convention on `assert_impl!/2`
+  * [Regex] Do not consider include captures on `Regex.split/3` results
+  * [Stream] Implement the `Inspect` protocol for Streams so we do not leak the Stream representation
+
+* Deprecations
+  * [IEx] IEx color configuration expects a list of atoms instead of a string with colors separated by comma
+  * [Inspect] `Inspect.Algebra.surround_many/6` now expects Inspect.Opts instead of an integer limit
+  * [Inspect] `Inspect.Algebra.pretty/2` is deprecated in favor of `Inspect.Algebra.format/2` that instead returns iodata. This function was used only by documentation examples and it is unlikely to affect actual code
+  * [IO] `IO.ANSI.terminal?` is deprecated in favor of `IO.ANSI.enabled?`
+  * [IO] `IO.ANSI.escape/2` and `IO.ANSI.escape_fragment/2` is deprecated in favor of `IO.ANSI.format/2` and `IO.ANSI.format_fragment/2`
+  * [Kernel] Leading `0` for octals is deprecated in favor of `0o`
+  * [Kernel] `0X` for hexadecimals is deprecated in favor of `0x`
+  * [Kernel] `0B` for binaries is deprecated in favor of `0b`
+  * [Mix] Mix color configuration expects a list of atoms instead of a string with colors separated by comma
+  * [String] `\NNN`, `\NN` and `\N` for octals are deprecated inside string, sigils and chars in favor of hexadecimal entries with `\x`
+
+* Backwards incompatible changes
+  * [Kernel] `binding/1` and `binding/2` expecting a list were removed
+  * [Regex] Do not consider include captures on `Regex.split/3` results
+
+## v0.14.3 (2014-07-12)
+
+* Enhancements
+  * [Access] Allow function access on `get_in/2` and `get_and_update_in/3`
+  * [Enum] Add `Enum.sort_by/3`
+  * [ExUnit] Match the line filter by proximity instead of exact match
+  * [Float] Support precision in `Float.ceil/1` and `Float.floor/1`
+  * [IO] Add `IO.(bin)read(device, :all)`
+  * [Kernel] Print a warning if a dangling `@doc` clause is found
+  * [Mix] Use absolute symbolic links on Windows for `_build` instead of copying
+  * [Mix] Add `Mix.compilers` that returns all default compilers used by mix tasks
+  * [Mix] Issue warning and reset mtime for source files from the future
+  * [Mix] Support task aliases in Mix
+  * [OptionParser] Add `OptionParser.split/1` that splits a string into argv
+  * [Record] Allow a record to be converted to a keyword list with `record(some_record)`
+  * [String] Improve performance of `String.split/1`
+  * [Typespec] Allow `%Struct{}` syntax to be used in typespecs
+  * [Typespec] Allow `record(:record, fields)` syntax to be used in typespecs
+
+* Bug fixes
+  * [IEx] Do not print ANSI sequences on `IEx.Helpers.clear/0` if ANSI sequences are not supported
+  * [Inspect] Ensure `Inspect.Algebra.to_doc/2` doesn't go into a loop when there is a failure printing a struct
+  * [Kernel] `|>`, `<<<`, `>>>` and `^^^` made left associative in operator table
+  * [Kernel] `<`, `>`, `<=`, `>=` given higher precedence than comparison operators (`==`, `!=`, etc) in the operator table
+  * [Kernel] Run command line and escripts in a process that does not trap exits
+  * [Kernel] Fix a bug where Mix paths had higher priority than CLI ones, causing protocol consolidations to not be properly loaded
+  * [Kernel] Fix wording on error messages when a check/guard always passes or always fails
+  * [Kernel] Fix a bug where an unused function warning was printed even when the function was used via `defoverridable`
+  * [Kernel] Improve typespecs so they don't generate supertype dialyzer warnings
+  * [Macro] `to_string` correctly displays sigils
+  * [Mix] Ensure Mix dependencies are not compiled every second time when `mix deps.compile` is invoked
+  * [Mix] Fix a bug where `Mix.shell.error/1` and friends choked when printing a map
+  * [Mix] Ensure multiple `@external_resource` entries are read by Mix compilers
+  * [Mix] Fix a bug where tasks for umbrella projects were not properly reenabled
+  * [Stream] Fix bug when `flat_map` is used inside another `flat_map` with an Enumerable
+  * [Typespec] Fix a bug where the `list` typespec was incorrectly rendered as `[]`
+
+* Soft deprecations (no warnings emitted)
+  * [Kernel] Using a list for bitstring modifiers is deprecated (as in `<<x :: [little, utf16]>>`), please use `-` as the separator instead (as in `<<x :: little-utf16>>`)
+  * [System] `System.cmd/1` is deprecated in favor of `System.cmd/3`
+
+* Deprecations
+  * [Mix] `mix escriptize` is deprecated in favor of `escript.build`
+  * [Mix] `mix local.install` and `mix local.uninstall` have been deprecated in favor of `mix archive.install` and `mix archive.uninstall` respectively
+  * [Mix] `:embed_extra_apps` for escripts is deprecated, instead list the dependencies inside `def application`
+  * [System] Giving a char list to `System.find_executable/1` is deprecated
+
+* Backwards incompatible changes
+  * [Access] No longer fill in missing intermediate values with empty maps
+  * [Float] `Float.ceil/2` and `Float.floor/2` now always returns floats and no longer accept integers
+  * [Kernel] `defstruct` no longer automatically defines a type
+  * [Kernel] `exit(integer)` is no longer supported from scripts to configure the exit signal. Use `exit({:shutdown, integer})` instead
+  * [Kernel] Default argument values have to be defined in a function head if the function has multiple clauses
+  * [Mix] `mix archive.build` replaces the functionality of `mix archive`, `mix archive` now lists locally installed archives
+  * [Mix] `Mix.shell.info/1` no longer automatically escape ANSI sequences. Instead if has to be explicitly enabled with the `ansi: true` option
+  * [OptionParser] `--no-SWITCH` are only allowed for declared booleans switches

 ## v0.14.2 (2014-06-29)

@@ -28,7 +316,7 @@

 * Bug fixes
  * [CLI] Support paths inside archives in `-pa` and `-pz` options
-  * [IEx] Remove delay when printing data from the an application start callback
+  * [IEx] Remove delay when printing data from the application start callback
  * [IEx] Ensure we show a consistent error when we cannot evaluate `.iex.exs`
  * [Kernel] Ensure derived protocols are defined with a file
  * [Kernel] Change precedence of `&` to not special case `/`
@@ -70,7 +358,7 @@
  * [URI] `encode/1` does not escape reserved/unreserved characters by default nor encodes whitespace as `+` (check `URI.encode_www_form/1` and `URI.decode_www_form/1` for previous behaviour)

 * Deprecations
-  * [Mix] `:escript_*` options were moved into a single `:escript` group
+  * [Mix] `:escript_*` options moved into a single `:escript` group

 * Backwards incompatible changes
  * [GenEvent] `GenEvent.stream/2` defaults to `:sync` mode
@@ -10,7 +10,7 @@ Use the issues tracker for:
 * [bug reports](#bugs-reports)
 * [submitting pull requests](#pull-requests)

-Please **do not** use the issues tracker for personal support requests nor feature requests. Support requests should be send to:
+Please **do not** use the issue tracker for personal support requests nor feature requests. Support requests should be sent to:

 * [the elixir-talk mailing list](http://groups.google.com/group/elixir-lang-talk)
 * [Stack Overflow](http://stackoverflow.com/questions/ask?tags=elixir)
@@ -18,7 +18,7 @@ Please **do not** use the issues tracker for personal support requests nor featu

 Feature requests can be discussed on [the elixir-core mailing list](http://groups.google.com/group/elixir-lang-core).

-We do our best to keep the issues tracker tidy and organized, making it useful
+We do our best to keep the issue tracker tidy and organized, making it useful
 for everyone. For example, we classify open issues per application and perceived
 difficulty of the issue, making it easier for developers to
 [contribute to Elixir](#contributing).
@@ -107,26 +107,6 @@ check [the official build status on Travis-CI](https://travis-ci.org/elixir-lang
 With tests running and passing, you are ready to contribute to Elixir and
 send your pull requests.

-### Building on Windows
-
-There are a few extra steps you'll need to take for contributing from Windows.
-Basically, once you have Erlang 17, Git, and MSYS from MinGW on your system,
-you're all set.  Specifically, here's what you need to do to get up and running:
-
-1. Install [Git](http://www.git-scm.com/download/win), 
-[Erlang](http://www.erlang.org/download.html), and the
-[MinGW Installation Manager](http://sourceforge.net/projects/mingw/files/latest/download?source=files).
-2. Use the MinGW Installation Manager to install the msys-bash, msys-make, and
-msys-grep packages.
-3. Add `;C:\Program Files (x86)\Git\bin;C:\Program Files\erl6.0\bin;C:\Program Files\erl6.0\erts-6.0\bin;C:\MinGW\msys\1.0\bin`
-to your "Path" environment variable .  (This is under Control Panel > System 
-and Security > System > Advanced system settings > Environment Variables > 
-System variables)
-
-You can now work in the Command Prompt similar to how you would on other OS'es,
-except for some things (like creating symlinks) you'll need to run the Command
-Prompt as an Administrator.
-
 ## Contributing Documentation

 Code documentation (`@doc`, `@moduledoc`, `@typedoc`) has a special convention:
@@ -279,7 +259,6 @@ We have saved some excellent pull requests we have received in the past in case
 you are looking for some examples:

 * https://github.com/elixir-lang/elixir/pull/992
-* https://github.com/elixir-lang/elixir/pull/1041
 * https://github.com/elixir-lang/elixir/pull/1058
 * https://github.com/elixir-lang/elixir/pull/1059

@@ -1,4 +1,4 @@
-Copyright 2012-2013 Plataformatec.
+Copyright 2012 Plataformatec

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -1,4 +1,6 @@
 REBAR := rebar
+DOCS := v1.0
+CANONICAL := stable
 ELIXIRC := bin/elixirc --verbose --ignore-module-conflict
 ERLC := erlc -I lib/elixir/include
 ERL := erl -I lib/elixir/include -noshell -pa lib/elixir/ebin
@@ -11,7 +13,7 @@ INSTALL_DIR = $(INSTALL) -m755 -d
 INSTALL_DATA = $(INSTALL) -m644
 INSTALL_PROGRAM = $(INSTALL) -m755

-.PHONY: install compile erlang elixir dialyze test clean docs release_docs release_zip check_erlang_release
+.PHONY: install compile erlang elixir build_plt clean_plt dialyze test clean docs release_docs release_zip check_erlang_release
 .NOTPARALLEL: compile

 #==> Functions
@@ -32,7 +34,7 @@ $(1): lib/$(1)/ebin/Elixir.$(2).beam lib/$(1)/ebin/$(1).app
 lib/$(1)/ebin/$(1).app: lib/$(1)/mix.exs
 	$(Q) mkdir -p lib/$(1)/_build/shared/lib/$(1)
 	$(Q) cp -R lib/$(1)/ebin lib/$(1)/_build/shared/lib/$(1)/
-	$(Q) cd lib/$(1) && ../../bin/elixir -e "Mix.start(:permanent, [])" -r mix.exs -e "Mix.Task.run('compile.app')"
+	$(Q) cd lib/$(1) && ../../bin/elixir -e 'Mix.start(:permanent, [])' -r mix.exs -e 'Mix.Task.run("compile.app")'
 	$(Q) cp lib/$(1)/_build/shared/lib/$(1)/ebin/$(1).app lib/$(1)/ebin/$(1).app
 	$(Q) rm -rf lib/$(1)/_build

@@ -68,10 +70,10 @@ erlang:
 # Since Mix depends on EEx and EEx depends on
 # Mix, we first compile EEx without the .app
 # file, then mix and then compile EEx fully
-elixir: stdlib lib/eex/ebin/Elixir.EEx.beam mix ex_unit eex iex
+elixir: stdlib lib/eex/ebin/Elixir.EEx.beam mix ex_unit logger eex iex

 stdlib: $(KERNEL) VERSION
-$(KERNEL): lib/elixir/lib/*.ex lib/elixir/lib/*/*.ex
+$(KERNEL): lib/elixir/lib/*.ex lib/elixir/lib/*/*.ex lib/elixir/lib/*/*/*.ex
 	$(Q) if [ ! -f $(KERNEL) ]; then                    \
 		echo "==> bootstrap (compile)";                 \
 		$(ERL) -s elixir_compiler core -s erlang halt;  \
@@ -86,10 +88,11 @@ $(KERNEL): lib/elixir/lib/*.ex lib/elixir/lib/*/*.ex
 unicode: $(UNICODE)
 $(UNICODE): lib/elixir/unicode/*
 	@ echo "==> unicode (compile)";
-	@ echo "This step can take up to a minute to compile in order to embed the Unicode database"
+	@ echo "Embedding the Unicode database... (this may take a while)"
 	$(Q) cd lib/elixir && ../../$(ELIXIRC) unicode/unicode.ex -o ebin;

 $(eval $(call APP_TEMPLATE,ex_unit,ExUnit))
+$(eval $(call APP_TEMPLATE,logger,Logger))
 $(eval $(call APP_TEMPLATE,eex,EEx))
 $(eval $(call APP_TEMPLATE,mix,Mix))
 $(eval $(call APP_TEMPLATE,iex,IEx))
@@ -123,16 +126,18 @@ clean_exbeam:

 #==> Release tasks

-SOURCE_REF = $(shell head="$$(git rev-parse HEAD)" tag="$$(git tag --points-at $$head | tail -1)" ; echo "$${tag:-$$head}\c")
-DOCS = bin/elixir ../ex_doc/bin/ex_doc "$(1)" "$(VERSION)" "lib/$(2)/ebin" -m "$(3)" -u "https://github.com/elixir-lang/elixir" --source-ref "$(call SOURCE_REF)" -o docs/$(2) -p http://elixir-lang.org/docs.html
+LOGO_PATH = $(shell test -f ../docs/logo.png && echo "--logo ../docs/logo.png")
+SOURCE_REF = $(shell tag="$(call GIT_TAG)" revision="$(call GIT_REVISION)"; echo "$${tag:-$$revision}\c")
+COMPILE_DOCS = bin/elixir ../ex_doc/bin/ex_doc "$(1)" "$(VERSION)" "lib/$(2)/ebin" -m "$(3)" -u "https://github.com/elixir-lang/elixir" --source-ref "v$(VERSION)" $(call LOGO_PATH) -o doc/$(2) -a http://elixir-lang.org/docs/$(CANONICAL)/$(2)/ -p http://elixir-lang.org/docs.html

 docs: compile ../ex_doc/bin/ex_doc
-	$(Q) rm -rf docs
-	$(call DOCS,Elixir,elixir,Kernel)
-	$(call DOCS,EEx,eex,EEx)
-	$(call DOCS,Mix,mix,Mix)
-	$(call DOCS,IEx,iex,IEx)
-	$(call DOCS,ExUnit,ex_unit,ExUnit)
+	$(Q) rm -rf doc
+	$(call COMPILE_DOCS,Elixir,elixir,Kernel)
+	$(call COMPILE_DOCS,EEx,eex,EEx)
+	$(call COMPILE_DOCS,Mix,mix,Mix)
+	$(call COMPILE_DOCS,IEx,iex,IEx)
+	$(call COMPILE_DOCS,ExUnit,ex_unit,ExUnit)
+	$(call COMPILE_DOCS,Logger,logger,Logger)

 ../ex_doc/bin/ex_doc:
 	@ echo "ex_doc is not found in ../ex_doc as expected. See README for more information."
@@ -140,12 +145,21 @@ docs: compile ../ex_doc/bin/ex_doc

 release_zip: compile
 	rm -rf v$(VERSION).zip
-	zip -9 -r v$(VERSION).zip bin CHANGELOG.md LEGAL lib/*/ebin LICENSE README.md VERSION
+	zip -9 -r v$(VERSION).zip bin CHANGELOG.md LEGAL lib/*/ebin LICENSE Makefile README.md VERSION

 release_docs: docs
-	cd ../docs
-	rm -rf ../docs/master
-	mv docs ../docs/master
+	rm -rf ../docs/$(DOCS)/*/
+	mv doc/* ../docs/$(DOCS)
+
+# This task requires aws-cli to be installed and set up for access to s3.hex.pm
+# See: http://docs.aws.amazon.com/cli/latest/userguide/cli-chap-getting-set-up.html
+
+publish_mix: compile
+	cd lib/mix && MIX_ENV=prod mix escript.build
+	aws s3 cp lib/mix/mix s3://s3.hex.pm/builds/mix/v$(VERSION)/mix --acl public-read
+	aws s3 cp lib/mix/mix s3://s3.hex.pm/builds/mix/mix --acl public-read
+	rm lib/mix/mix
+	rm -rf lib/mix/_build

 #==> Tests tasks

@@ -164,7 +178,7 @@ $(TEST_EBIN)/%.beam: $(TEST_ERL)/%.erl
 	$(Q) mkdir -p $(TEST_EBIN)
 	$(Q) $(ERLC) -o $(TEST_EBIN) $<

-test_elixir: test_stdlib test_ex_unit test_doc_test test_mix test_eex test_iex
+test_elixir: test_stdlib test_ex_unit test_logger test_doc_test test_mix test_eex test_iex

 test_doc_test: compile
 	@ echo "==> doctest (exunit)"
@@ -173,16 +187,26 @@ test_doc_test: compile
 test_stdlib: compile
 	@ echo "==> elixir (exunit)"
 	$(Q) exec epmd & exit
-	$(Q) cd lib/elixir && ../../bin/elixir -r "test/elixir/test_helper.exs" -pr "test/elixir/**/*_test.exs";
+	$(Q) if [ "$(OS)" = "Windows_NT" ]; then \
+		cd lib/elixir && cmd //C call ../../bin/elixir.bat -r "test/elixir/test_helper.exs" -pr "test/elixir/**/*_test.exs"; \
+	else \
+		cd lib/elixir && ../../bin/elixir -r "test/elixir/test_helper.exs" -pr "test/elixir/**/*_test.exs"; \
+	fi

-.dialyzer.base_plt:
-	@ echo "==> Adding Erlang/OTP basic applications to a new base PLT"
-	$(Q) dialyzer --output_plt .dialyzer.base_plt --build_plt --apps erts kernel stdlib compiler tools syntax_tools parsetools
+#==> Dialyzer tasks

-dialyze: .dialyzer.base_plt
-	$(Q) rm -f .dialyzer_plt
-	$(Q) cp .dialyzer.base_plt .dialyzer_plt
-	@ echo "==> Adding Elixir to PLT..."
-	$(Q) dialyzer --plt .dialyzer_plt --add_to_plt -r lib/elixir/ebin lib/ex_unit/ebin lib/eex/ebin lib/iex/ebin lib/mix/ebin
+DIALYZER_OPTS = --no_check_plt --fullpath -Werror_handling -Wunmatched_returns -Wunderspecs
+PLT = .elixir.plt
+
+$(PLT):
+	@ echo "==> Building PLT with Elixir's dependencies..."
+	$(Q) dialyzer --output_plt $(PLT) --build_plt --apps erts kernel stdlib compiler syntax_tools parsetools tools ssl inets
+
+clean_plt:
+	$(Q) rm -f $(PLT)
+
+build_plt: clean_plt $(PLT)
+
+dialyze: compile $(PLT)
 	@ echo "==> Dialyzing Elixir..."
-	$(Q) dialyzer --plt .dialyzer_plt -r lib/elixir/ebin lib/ex_unit/ebin lib/eex/ebin lib/iex/ebin lib/mix/ebin
+	$(Q) dialyzer --plt $(PLT) $(DIALYZER_OPTS) lib/*/ebin
@@ -12,6 +12,8 @@ If you want to contribute to Elixir or run it from source, clone this repository
    $ cd elixir
    $ make clean test

+> Note: if you are running on Windows, [this article includes important notes for compiling Elixir from source on Windows](https://github.com/elixir-lang/elixir/wiki/Windows).
+
 If Elixir fails to build (specifically when pulling in a new version via git), be sure to remove any previous build artifacts by running `make clean`, then `make test`.

 If tests pass, you are ready to move on to the [Getting Started guide][1] or to try Interactive Elixir by running: `bin/iex` in your terminal.
@@ -1,31 +1,43 @@
 # Release process

+## All releases
+
 This document simply outlines the release process:

-1. Remove `-dev` extension from VERSION
+1. Ensure you are running on the oldest supported Erlang version

-2. Ensure CHANGELOG is updated and timestamp
+2. Remove all `-dev` extension from versions (see below for all files)

-3. Commit changes above with title "Release vVERSION" and generate new tag
+3. Ensure CHANGELOG is updated and add current date

-4. Run `make clean test` to ensure all tests pass from scratch and the CI is green
+4. Commit changes above with title "Release vVERSION" and generate new tag

-5. Push master and tags
+5. Run `make clean test` to ensure all tests pass from scratch and the CI is green

-6. Release new docs with `make release_docs`, move docs to `docs/stable`
+6. Ensure minimum supported Hex works with new release (instructions upcoming)

-7. Release new zip with `make release_zip`, push new zip to GitHub Releases
+7. Push branch and the new tag

-8. Merge master into stable branch and push it
+8. Release new docs with `make release_docs`, copy docs to `docs/stable` if appropriate, and push

-9. After release, bump versions, add `-dev` back and commit
+9. Release new zip with `make release_zip`, push `Precompiled.zip` to GitHub Releases

-10. `make release_docs` once again and push it to `elixir-lang.org`
+10. Add the release to `elixir.csv` file in `elixir-lang/elixir-lang.github.com`

-11. Also update `release` file in `elixir-lang.org`
+11. Build and push standalone Mix with `make publish_mix` (requires AWS credentials)
+
+## New vMAJOR.MINOR releases
+
+12. Create a new branch "vMAJOR.MINOR"
+
+13. Move docs generation to `docs/vMAJOR.MINOR` and copy them from `docs/stable`
+
+14. In master, bump versions, start new CHANGELOG, add `-dev` back and commit "Start vVERSION+1"
+
+15. `make release_docs` and push it to `elixir-lang/docs`

 ## Places where version is mentioned

-* VERSION
-* CHANGELOG
-* src/elixir.app.src
+* VERSION (make sure there is no newline in this file)
+* CHANGELOG.md
+* src/elixir.app.src (not lib/elixir/src/elixir.app.src)
@@ -1 +1 @@
-0.14.3-dev
+1.0.5
@@ -80,7 +80,14 @@ done

 SELF=$(readlink_f "$0")
 SCRIPT_PATH=$(dirname "$SELF")
-if [ "$MODE" != "iex" ]; then ERL="$ERL -noshell -s elixir start_cli"; fi
+
+if [ "$OSTYPE" = "cygwin" ]; then SCRIPT_PATH=$(cygpath -m "$SCRIPT_PATH"); fi
+if [ "$MODE" != "iex" ]; then ERL="-noshell -s elixir start_cli $ERL"; fi
+
+# Check for terminal support
+if [ "$OS" != "Windows_NT" ]; then
+  if test -t 1 -a -t 2; then ERL="-elixir ansi_enabled true $ERL"; fi
+fi

 if [ -z "$ERL_PATH" ]; then
  if [ -f "$SCRIPT_PATH/../releases/RELEASES" ] && [ -f "$SCRIPT_PATH/erl" ]; then
@@ -1,4 +1,5 @@
@echo off
+setlocal
 if "%1"==""       goto documentation
 if "%1"=="--help" goto documentation
 if "%1"=="-h"     goto documentation
@@ -22,12 +23,13 @@ echo   --sname name      Makes and assigns a short name to the distributed node
 echo   --cookie cookie   Sets a cookie for this distributed node
 echo   --hidden          Makes a hidden node
 echo   --detached        Starts the Erlang VM detached from console
+echo   --werl            Uses Erlang's Windows shell GUI
 echo   --no-halt         Does not halt the Erlang VM after execution
 echo.
 echo ** Options marked with (*) can be given more than once
 echo ** Options given after the .exs file or -- are passed down to the executed code
 echo ** Options can be passed to the erlang runtime using ELIXIR_ERL_OPTIONS or --erl
-goto :EOF
+goto end

 :parseopts

@@ -46,6 +48,9 @@ set beforeExtra=
 rem Flag which determines whether or not to use werl vs erl
 set useWerl=0

+rem Designates which mode / Elixir component to run as
+set runMode="elixir"
+
 rem Recursive loop called for each parameter that parses the cmd line parameters
 :startloop
 set par="%1"
@@ -59,23 +64,24 @@ if "%par%"=="""" (
  goto :expand_erl_libs
 )
 rem ******* EXECUTION OPTIONS **********************
-IF "%par%"==""+iex"" (Set useWerl=1)
-rem ******* ERLANG PARAMETERS **********************
-IF NOT "%par%"=="%par:--detached=%" (Set parsErlang=%parsErlang% -detached) 
-IF NOT "%par%"=="%par:--hidden=%"   (Set parsErlang=%parsErlang% -hidden)
-IF NOT "%par%"=="%par:--cookie=%"   (Set parsErlang=%parsErlang% -setcookie %1 && shift)
-IF NOT "%par%"=="%par:--sname=%"    (Set parsErlang=%parsErlang% -sname %1 && shift) 
-IF NOT "%par%"=="%par:--name=%"     (Set parsErlang=%parsErlang% -name %1 && shift) 
-IF NOT "%par%"=="%par:--erl=%"      (Set beforeExtra=%beforeExtra% %~1 && shift) 
+IF "%par%"==""--werl"" (Set useWerl=1)
+IF "%par%"==""+iex"" (Set runMode="iex")
 rem ******* elixir parameters **********************
 rem Note: we don't have to do anything with options that don't take an argument
-IF NOT "%par%"=="%par:-e=%"      (shift) 
-IF NOT "%par%"=="%par:-r=%"      (shift) 
-IF NOT "%par%"=="%par:-pr=%"     (shift) 
-IF NOT "%par%"=="%par:-pa=%"     (shift) 
-IF NOT "%par%"=="%par:-pz=%"     (shift) 
-IF NOT "%par%"=="%par:--app=%"   (shift) 
-IF NOT "%par%"=="%par:--remsh=%" (shift) 
+IF """"=="%par:-e=%"      (shift) 
+IF """"=="%par:-r=%"      (shift) 
+IF """"=="%par:-pr=%"     (shift) 
+IF """"=="%par:-pa=%"     (shift) 
+IF """"=="%par:-pz=%"     (shift) 
+IF """"=="%par:--app=%"   (shift) 
+IF """"=="%par:--remsh=%" (shift) 
+rem ******* ERLANG PARAMETERS **********************
+IF """"=="%par:--detached=%" (Set parsErlang=%parsErlang% -detached) 
+IF """"=="%par:--hidden=%"   (Set parsErlang=%parsErlang% -hidden)
+IF """"=="%par:--cookie=%"   (Set parsErlang=%parsErlang% -setcookie %1 && shift)
+IF """"=="%par:--sname=%"    (Set parsErlang=%parsErlang% -sname %1 && shift) 
+IF """"=="%par:--name=%"     (Set parsErlang=%parsErlang% -name %1 && shift) 
+IF """"=="%par:--erl=%"      (Set beforeExtra=%beforeExtra% %~1 && shift) 
 goto:startloop

 rem ******* assume all pre-params are parsed ********************
@@ -88,8 +94,13 @@ for  /d %%d in ("%originPath%..\lib\*.") do (
 )
 SETLOCAL disabledelayedexpansion
 :run
-IF %useWerl% EQU 1 (
-    werl.exe %ext_libs% %ELIXIR_ERL_OPTIONS% %parsErlang% -s elixir start_cli %beforeExtra% -extra %*
-) ELSE (
-    erl.exe %ext_libs% -noshell %ELIXIR_ERL_OPTIONS% %parsErlang% -s elixir start_cli %beforeExtra% -extra %*
+IF NOT %runMode% == "iex" (
+  set beforeExtra=-s elixir start_cli %beforeExtra%
 )
+IF %useWerl% EQU 1 (
+  start werl.exe %ext_libs% %ELIXIR_ERL_OPTIONS% %parsErlang% %beforeExtra% -extra %*
+) ELSE (
+  erl.exe %ext_libs% -noshell %ELIXIR_ERL_OPTIONS% %parsErlang% %beforeExtra% -extra %*
+)
+:end
+endlocal
@@ -38,4 +38,6 @@ readlink_f () {

 SELF=$(readlink_f "$0")
 SCRIPT_PATH=$(dirname "$SELF")
-exec "$SCRIPT_PATH"/elixir --no-halt --erl "-user Elixir.IEx.CLI" +iex "$@"
+
+if [ "$OS" = "Windows_NT" ]; then NOSHELL="-noshell "; fi
+exec "$SCRIPT_PATH"/elixir --no-halt --erl "$NOSHELL -user Elixir.IEx.CLI" +iex "$@"
@@ -1,3 +1,4 @@
 #!/usr/bin/env elixir
+# Reminder: apply any changes in this file to bin\mix.bat
 Mix.start
 Mix.CLI.main
@@ -1,2 +1,2 @@
@echo off
-call "%~dp0\elixir.bat" "%~dp0\mix" %*
+call "%~dp0\elixir.bat" -e Mix.start -e Mix.CLI.main %*
@@ -1,27 +1,23 @@
-# Initialize with path to mix.bat relative to caller's working directory
-$toCmd = '' + (Resolve-Path -relative (Split-Path $MyInvocation.MyCommand.Path)) + '\mix.bat'
+# Store path to mix.bat as a FileInfo object
+$mixBatPath = (Get-ChildItem (((Get-ChildItem $MyInvocation.MyCommand.Path).Directory.FullName) + '\mix.bat'))
+$newArgs = @()

-foreach ($arg in $args)
+for ($i = 0; $i -lt $args.length; $i++)
 {
-  $toCmd += ' '
-  
-  if ($arg -is [array])
+  if ($args[$i] -is [array])
  {
    # Commas created the array so we need to reintroduce those commas
-    for ($i = 0; $i -lt $arg.length; $i++)
+    for ($j = 0; $j -lt $args[$i].length - 1; $j++)
    {
-      $toCmd += $arg[$i]
-      if ($i -ne ($arg.length - 1))
-      {
-        $toCmd += ', '
-      }
+      $newArgs += ($args[$i][$j] + ',')
    }
+    $newArgs += $args[$i][-1]
  }
  else
  {
-    $toCmd += $arg
+    $newArgs += $args[$i]
  }
 }

 # Corrected arguments are ready to pass to batch file
-cmd /c $toCmd
+& $mixBatPath $newArgs
@@ -1,5 +1,9 @@
 defmodule EEx.SyntaxError do
-  defexception [:message]
+  defexception [:message, :file, :line]
+
+  def message(exception) do
+    "#{exception.file}:#{exception.line}: #{exception.message}"
+  end
 end

 defmodule EEx do
@@ -36,8 +40,7 @@ defmodule EEx do

    * `:line` - the line to be used as the template start. Defaults to 1.
    * `:file` - the file to be used in the template. Defaults to the given
-                  file the template is read from or to "nofile" when compiling
-                  from a string.
+      file the template is read from or to "nofile" when compiling from a string.
    * `:engine` - the EEx engine to be used for compilation.

  ## Engine
@@ -12,10 +12,14 @@ defmodule EEx.Compiler do
  def compile(source, opts) do
    file   = opts[:file] || "nofile"
    line   = opts[:line] || 1
-    tokens = EEx.Tokenizer.tokenize(source, line)
+    case EEx.Tokenizer.tokenize(source, line) do
+      {:ok, tokens} ->
        state = %{engine: opts[:engine] || @default_engine,
                  file: file, line: line, quoted: [], start_line: nil}
        generate_buffer(tokens, "", [], state)
+      {:error, line, message} ->
+        raise EEx.SyntaxError, line: line, file: file, message: message
+    end
  end

  # Generates the buffers by handling each expression from the tokenizer
@@ -51,16 +55,17 @@ defmodule EEx.Compiler do
    {buffer, t}
  end

-  defp generate_buffer([{:end_expr, line, _, chars}|_], _buffer, [], _state) do
-    raise EEx.SyntaxError, message: "unexpected token: #{inspect chars} at line #{inspect line}"
+  defp generate_buffer([{:end_expr, line, _, chars}|_], _buffer, [], state) do
+    raise EEx.SyntaxError, message: "unexpected token #{inspect chars}", file: state.file, line: line
  end

  defp generate_buffer([], buffer, [], state) do
    state.engine.handle_body(buffer)
  end

-  defp generate_buffer([], _buffer, _scope, _state) do
-    raise EEx.SyntaxError, message: "unexpected end of string. expecting a closing <% end %>."
+  defp generate_buffer([], _buffer, _scope, state) do
+    raise EEx.SyntaxError, message: "unexpected end of string, expected a closing '<% end %>'",
+                           file: state.file, line: state.line
  end

  # Creates a placeholder and wrap it inside the expression block
@@ -64,7 +64,8 @@ defmodule EEx.Engine do
      end

  """
-  def handle_assign({:@, line, [{name, _, atom}]}) when is_atom(name) and is_atom(atom) do
+  def handle_assign({:@, meta, [{name, _, atom}]}) when is_atom(name) and is_atom(atom) do
+    line = meta[:line] || 0
    quote line: line, do: Dict.get(var!(assigns), unquote(name))
  end

@@ -97,16 +98,16 @@ defmodule EEx.Engine do
  """
  def handle_expr(buffer, "=", expr) do
    quote do
-      tmp = unquote(buffer)
-      tmp <> to_string(unquote(expr))
+      tmp1 = unquote(buffer)
+      tmp1 <> String.Chars.to_string(unquote(expr))
    end
  end

  def handle_expr(buffer, "", expr) do
    quote do
-      tmp = unquote(buffer)
+      tmp2 = unquote(buffer)
      unquote(expr)
-      tmp
+      tmp2
    end
  end
 end
@@ -1,63 +1,3 @@
-defmodule EEx.TransformerEngine do
-  @moduledoc false
-
-  @doc false
-  defmacro __using__(_) do
-    quote do
-      @behaviour EEx.Engine
-
-      def handle_body(body) do
-        EEx.Engine.handle_body(body)
-      end
-
-      def handle_text(buffer, text) do
-        EEx.Engine.handle_text(buffer, text)
-      end
-
-      def handle_expr(buffer, mark, expr) do
-        EEx.Engine.handle_expr(buffer, mark, transform(expr))
-      end
-
-      defp transform({a, b, c}) do
-        {transform(a), b, transform(c)}
-      end
-
-      defp transform({a, b}) do
-        {transform(a), transform(b)}
-      end
-
-      defp transform(list) when is_list(list) do
-        for i <- list, do: transform(i)
-      end
-
-      defp transform(other) do
-        other
-      end
-
-      defoverridable [transform: 1, handle_body: 1, handle_expr: 3, handle_text: 2]
-    end
-  end
-end
-
-defmodule EEx.AssignsEngine do
-  @moduledoc false
-
-  @doc false
-  defmacro __using__(_) do
-    quote unquote: false do
-      defp transform({:@, line, [{name, _, atom}]}) when is_atom(name) and is_atom(atom) do
-        quote do: Dict.get(var!(assigns), unquote(name))
-      end
-
-      defp transform(arg) do
-        super(arg)
-      end
-
-      defoverridable [transform: 1]
-    end
-  end
-end
-
 defmodule EEx.SmartEngine do
  @moduledoc """
  The default engine used by EEx.
@@ -3,7 +3,8 @@ defmodule EEx.Tokenizer do

  @doc """
  Tokenizes the given char list or binary.
-  It returns 4 different types of tokens as result:
+
+  It returns {:ok, list} with the following tokens:

    * `{:text, contents}`
    * `{:expr, line, marker, contents}`
@@ -11,34 +12,44 @@ defmodule EEx.Tokenizer do
    * `{:middle_expr, line, marker, contents}`
    * `{:end_expr, line, marker, contents}`

+  Or `{:error, line, error}` in case of errors.
  """
  def tokenize(bin, line) when is_binary(bin) do
    tokenize(String.to_char_list(bin), line)
  end

  def tokenize(list, line) do
-    Enum.reverse(tokenize(list, line, [], []))
+    tokenize(list, line, [], [])
  end

  defp tokenize('<%%' ++ t, line, buffer, acc) do
-    {buffer, new_line, rest} = tokenize_expr t, line, [?%, ?<|buffer]
+    case expr(t, line, [?%, ?<|buffer]) do
+      {:error, _, _} = error -> error
+      {:ok, buffer, new_line, rest} ->
        tokenize rest, new_line, [?>, ?%|buffer], acc
    end
+  end

  defp tokenize('<%#' ++ t, line, buffer, acc) do
-    {_, new_line, rest} = tokenize_expr t, line, []
+    case expr(t, line, []) do
+      {:error, _, _} = error -> error
+      {:ok, _, new_line, rest} ->
        tokenize rest, new_line, buffer, acc
    end
+  end

  defp tokenize('<%' ++ t, line, buffer, acc) do
    {marker, t} = retrieve_marker(t)
-    {expr, new_line, rest} = tokenize_expr t, line, []

+    case expr(t, line, []) do
+      {:error, _, _} = error -> error
+      {:ok, expr, new_line, rest} ->
        token = token_name(expr)
        acc   = tokenize_text(buffer, acc)
        final = {token, line, marker, Enum.reverse(expr)}
        tokenize rest, new_line, [], [final | acc]
    end
+  end

  defp tokenize('\n' ++ t, line, buffer, acc) do
    tokenize t, line + 1, [?\n|buffer], acc
@@ -49,7 +60,7 @@ defmodule EEx.Tokenizer do
  end

  defp tokenize([], _line, buffer, acc) do
-    tokenize_text(buffer, acc)
+    {:ok, Enum.reverse(tokenize_text(buffer, acc))}
  end

  # Retrieve marker for <%
@@ -64,20 +75,20 @@ defmodule EEx.Tokenizer do

  # Tokenize an expression until we find %>

-  defp tokenize_expr([?%, ?>|t], line, buffer) do
-    {buffer, line, t}
+  defp expr([?%, ?>|t], line, buffer) do
+    {:ok, buffer, line, t}
  end

-  defp tokenize_expr('\n' ++ t, line, buffer) do
-    tokenize_expr t, line + 1, [?\n|buffer]
+  defp expr('\n' ++ t, line, buffer) do
+    expr t, line + 1, [?\n|buffer]
  end

-  defp tokenize_expr([h|t], line, buffer) do
-    tokenize_expr t, line, [h|buffer]
+  defp expr([h|t], line, buffer) do
+    expr t, line, [h|buffer]
  end

-  defp tokenize_expr([], _line, _buffer) do
-    raise EEx.SyntaxError, message: "missing token: %>"
+  defp expr([], line, _buffer) do
+    {:error, line, "missing token '%>'"}
  end

  # Receive an expression content and check
@@ -19,6 +19,16 @@ defmodule EEx.SmartEngineTest do
    assert_eval "1\n2\n3\n", "<%= for x <- [1, 2, 3] do %><%= x %>\n<% end %>"
  end

+  test "compiled preserved line numbers" do
+    result = EEx.compile_string("<%= @hello %>", engine: EEx.SmartEngine)
+    Macro.prewalk(result, fn
+      {_left, meta, _right} ->
+        assert Keyword.get(meta, :line, 0) in [0, 1]
+      _ ->
+        :ok
+    end)
+  end
+
  defp assert_eval(expected, actual, binding \\ []) do
    result = EEx.eval_string(actual, binding, file: __ENV__.file)
    assert result == expected
@@ -5,23 +5,26 @@ defmodule EEx.TokenizerTest do
  require EEx.Tokenizer, as: T

  test "simple chars lists" do
-    assert T.tokenize('foo', 1) == [ {:text, 'foo'} ]
+    assert T.tokenize('foo', 1) == {:ok, [{:text, 'foo'}]}
  end

  test "simple strings" do
-    assert T.tokenize("foo", 1) == [ {:text, 'foo'} ]
+    assert T.tokenize("foo", 1) == {:ok, [{:text, 'foo'}]}
  end

  test "strings with embedded code" do
-    assert T.tokenize('foo <% bar %>', 1) == [ {:text, 'foo '}, {:expr, 1, "", ' bar '} ]
+    assert T.tokenize('foo <% bar %>', 1) ==
+           {:ok, [{:text, 'foo '}, {:expr, 1, "", ' bar '}]}
  end

  test "strings with embedded equals code" do
-    assert T.tokenize('foo <%= bar %>', 1) == [ {:text, 'foo '}, {:expr, 1, "=", ' bar '} ]
+    assert T.tokenize('foo <%= bar %>', 1) ==
+           {:ok, [{:text, 'foo '}, {:expr, 1, "=", ' bar '}]}
  end

  test "strings with more than one line" do
-    assert T.tokenize('foo\n<%= bar %>', 1) == [ {:text, 'foo\n'}, {:expr, 2, "=", ' bar '} ]
+    assert T.tokenize('foo\n<%= bar %>', 1) ==
+           {:ok, [{:text, 'foo\n'}, {:expr, 2, "=", ' bar '}]}
  end

  test "strings with more than one line and expression with more than one line" do
@@ -32,50 +35,50 @@ baz %>
 <% foo %>
 '''

-    assert T.tokenize(string, 1) == [
+    assert T.tokenize(string, 1) == {:ok, [
      {:text, 'foo '},
      {:expr, 1, "=", ' bar\n\nbaz '},
      {:text, '\n'},
      {:expr, 4, "", ' foo '},
      {:text, '\n'}
-    ] 
+    ]}
  end

  test "quotation" do
-    assert T.tokenize('foo <%% true %>', 1) == [
+    assert T.tokenize('foo <%% true %>', 1) == {:ok, [
      {:text, 'foo <% true %>'}
-    ]
+    ]}
  end

  test "quotation with do/end" do
-    assert T.tokenize('foo <%% true do %>bar<%% end %>', 1) == [
+    assert T.tokenize('foo <%% true do %>bar<%% end %>', 1) == {:ok, [
      {:text, 'foo <% true do %>bar<% end %>'}
-    ]
+    ]}
  end

  test "comments" do
-    assert T.tokenize('foo <%# true %>', 1) == [
+    assert T.tokenize('foo <%# true %>', 1) == {:ok, [
      {:text, 'foo '}
-    ]
+    ]}
  end

  test "comments with do/end" do
-    assert T.tokenize('foo <%# true do %>bar<%# end %>', 1) == [
+    assert T.tokenize('foo <%# true do %>bar<%# end %>', 1) == {:ok, [
      {:text, 'foo bar'}
-    ]
+    ]}
  end

  test "strings with embedded do end" do
-    assert T.tokenize('foo <% if true do %>bar<% end %>', 1) == [
+    assert T.tokenize('foo <% if true do %>bar<% end %>', 1) == {:ok, [
      {:text, 'foo '},
      {:start_expr, 1, "", ' if true do '},
      {:text, 'bar'},
      {:end_expr, 1, "", ' end '}
-    ]
+    ]}
  end

  test "strings with embedded -> end" do
-    assert T.tokenize('foo <% cond do %><% false -> %>bar<% true -> %>baz<% end %>', 1) == [
+    assert T.tokenize('foo <% cond do %><% false -> %>bar<% true -> %>baz<% end %>', 1) == {:ok, [
      {:text, 'foo '},
      {:start_expr, 1, "", ' cond do '},
      {:middle_expr, 1, "", ' false -> '},
@@ -83,23 +86,21 @@ baz %>
      {:middle_expr, 1, "", ' true -> '},
      {:text, 'baz'},
      {:end_expr, 1, "", ' end '}
-    ]
+    ]}
  end

  test "strings with embedded keywords blocks" do
-    assert T.tokenize('foo <% if true do %>bar<% else %>baz<% end %>', 1) == [
+    assert T.tokenize('foo <% if true do %>bar<% else %>baz<% end %>', 1) == {:ok, [
      {:text, 'foo '},
      {:start_expr, 1, "", ' if true do '},
      {:text, 'bar'},
      {:middle_expr, 1, "", ' else '},
      {:text, 'baz'},
      {:end_expr, 1, "", ' end '}
-    ]
+    ]}
  end

  test "raise syntax error when there is start mark and no end mark" do
-    assert_raise EEx.SyntaxError, "missing token: %>", fn ->
-      T.tokenize('foo <% :bar', 1)
-    end
+    assert T.tokenize('foo <% :bar', 1) == {:error, 1, "missing token '%>'"}
  end
 end
@@ -50,7 +50,8 @@ defmodule EExTest do
  use ExUnit.Case, async: true

  doctest EEx
-  doctest EEx.AssignsEngine
+  doctest EEx.Engine
+  doctest EEx.SmartEngine

  test "evaluates simple string" do
    assert_eval "foo bar", "foo bar"
@@ -110,25 +111,25 @@ defmodule EExTest do
  end

  test "raises a syntax error when the token is invalid" do
-    assert_raise EEx.SyntaxError, "missing token: %>", fn ->
+    assert_raise EEx.SyntaxError, "nofile:1: missing token '%>'", fn ->
      EEx.compile_string "foo <%= bar"
    end
  end

  test "raises a syntax error when end expression is found without a start expression" do
-    assert_raise EEx.SyntaxError, "unexpected token: ' end ' at line 1",  fn ->
+    assert_raise EEx.SyntaxError, "nofile:1: unexpected token ' end '",  fn ->
      EEx.compile_string "foo <% end %>"
    end
  end

  test "raises a syntax error when start expression is found without an end expression" do
-    assert_raise EEx.SyntaxError, "unexpected end of string. expecting a closing <% end %>.", fn ->
-      EEx.compile_string "foo <% if true do %>"
+    assert_raise EEx.SyntaxError, "nofile:2: unexpected end of string, expected a closing '<% end %>'", fn ->
+      EEx.compile_string "foo\n<% if true do %>"
    end
  end

-  test "raises a syntax error when nested end expression is found without an start expression" do
-    assert_raise EEx.SyntaxError, "unexpected token: ' end ' at line 1", fn ->
+  test "raises a syntax error when nested end expression is found without a start expression" do
+    assert_raise EEx.SyntaxError, "nofile:1: unexpected token ' end '", fn ->
      EEx.compile_string "foo <% if true do %><% end %><% end %>"
    end
  end
@@ -251,7 +252,7 @@ Number <%= x %>
    assert_eval expected, string
  end

-  test "do not consider already finished functions" do
+  test "properly handle functions on the left side of clauses" do
    expected = """
 foo

@@ -286,6 +287,18 @@ foo
    assert_eval "\n\n  Good\n \n", string
  end

+  test "evaluates expressions with buffers" do
+    string = """
+    <%= 123 %>
+    <% if true do %>
+      <%= 456 %>
+    <% end %>
+    <%= 789 %>
+    """
+
+    assert_eval "123\n\n789\n", string
+  end
+
  test "for comprehensions" do
    string = """
    <%= for _name <- packages || [] do %>
@@ -119,7 +119,7 @@ defimpl Access, for: Map do

  def get_and_update!(other, key, _fun) do
    raise ArgumentError,
-      "could not update key #{inspect key}. Expected map/struct, got: #{inspect other}"
+      "could not put/update key #{inspect key}. Expected map/struct, got: #{inspect other}"
  end
 end

@@ -132,8 +132,9 @@ defimpl Access, for: Atom do
    undefined(atom)
  end

-  def get_and_update(nil, _, fun) do
-    fun.(nil)
+  def get_and_update(nil, key, _fun) do
+    raise ArgumentError,
+      "could not put/update key #{inspect key} on a nil value"
  end

  def get_and_update(atom, _key, _fun) do
@@ -68,22 +68,22 @@ defmodule Agent do
  ## A word on distributed agents

  It is important to consider the limitations of distributed agents. Agents
-  work by sending anonymous functions between the caller and the agent.
-  In a distributed setup with multiple nodes, agents only work if the caller
-  (client) and the agent have the same version of a given module.
+  provides two APIs, one that works with anonymous functions and another
+  that expects explicit module, function and arguments.

-  This setup may exhibit issues when doing "rolling upgrades". By rolling
-  upgrades we mean the following situation: you wish to deploy a new version of
-  your software by *shutting down* some of your nodes and replacing them with
-  nodes running a new version of the software. In this setup, part of your
-  environment will have one version of a given module and the other part
-  another version (the newer one) of the same module; this may cause agents to
-  crash. That said, if you plan to run in distributed environments, agents
-  should likely be avoided.
+  In a distributed setup with multiple nodes, the API that accepts anonymous
+  functions only works if the caller (client) and the agent have the same
+  version of the caller module.

-  Note, however, that agents work fine if you want to perform hot code
-  swapping, as it keeps both the old and new versions of a given module.
-  We detail how to do hot code swapping with agents in the next section.
+  Keep in mind this issue also shows up when performing "rolling upgrades"
+  with agents. By rolling upgrades we mean the following situation: you wish
+  to deploy a new version of your software by *shutting down* some of your
+  nodes and replacing them with nodes running a new version of the software.
+  In this setup, part of your environment will have one version of a given
+  module and the other part another version (the newer one) of the same module.
+
+  The best solution is to simply use the explicit module, function and arguments
+  APIs when working with distributed agents.

  ## Hot code swapping

@@ -111,7 +111,7 @@ defmodule Agent do
  @type state :: term

  @doc """
-  Starts an agent linked to the current process.
+  Starts an agent linked to the current process with the given function.

  This is often used to start the agent as part of a supervision tree.

@@ -149,6 +149,18 @@ defmodule Agent do
    GenServer.start_link(Agent.Server, fun, options)
  end

+  @doc """
+  Starts an agent linked to the current process with the given module
+  function and arguments.
+
+  Same as `start_link/2` but a module, function and args are expected
+  instead of an anonymous function.
+  """
+  @spec start_link(module, atom, [any], GenServer.options) :: on_start
+  def start_link(module, fun, args, options \\ []) do
+    GenServer.start_link(Agent.Server, {module, fun, args}, options)
+  end
+
  @doc """
  Starts an agent process without links (outside of a supervision tree).

@@ -160,7 +172,18 @@ defmodule Agent do
  end

  @doc """
-  Gets the agent value and executes the given function.
+  Starts an agent with the given module function and arguments.
+
+  Similar to `start/2` but a module, function and args are expected
+  instead of an anonymous function.
+  """
+  @spec start(module, atom, [any], GenServer.options) :: on_start
+  def start(module, fun, args, options \\ []) do
+    GenServer.start(Agent.Server, {module, fun, args}, options)
+  end
+
+  @doc """
+  Gets an agent value via the given function.

  The function `fun` is sent to the `agent` which invokes the function
  passing the agent state. The result of the function invocation is
@@ -173,6 +196,18 @@ defmodule Agent do
    GenServer.call(agent, {:get, fun}, timeout)
  end

+  @doc """
+  Gets an agent value via the given function.
+
+  Same as `get/3` but a module, function and args are expected
+  instead of an anonymous function. The state is added as first
+  argument to the given list of args.
+  """
+  @spec get(agent, module, atom, [term], timeout) :: any
+  def get(agent, module, fun, args, timeout \\ 5000) do
+    GenServer.call(agent, {:get, {module, fun, args}}, timeout)
+  end
+
  @doc """
  Gets and updates the agent state in one operation.

@@ -188,6 +223,18 @@ defmodule Agent do
    GenServer.call(agent, {:get_and_update, fun}, timeout)
  end

+  @doc """
+  Gets and updates the agent state in one operation.
+
+  Same as `get_and_update/3` but a module, function and args are expected
+  instead of an anonymous function. The state is added as first
+  argument to the given list of args.
+  """
+  @spec get_and_update(agent, module, atom, [term], timeout) :: any
+  def get_and_update(agent, module, fun, args, timeout \\ 5000) do
+    GenServer.call(agent, {:get_and_update, {module, fun, args}}, timeout)
+  end
+
  @doc """
  Updates the agent state.

@@ -197,11 +244,23 @@ defmodule Agent do
  A timeout can also be specified (it has a default value of 5000).
  This function always returns `:ok`.
  """
-  @spec update(agent, (state -> state)) :: :ok
+  @spec update(agent, (state -> state), timeout) :: :ok
  def update(agent, fun, timeout \\ 5000) when is_function(fun, 1) do
    GenServer.call(agent, {:update, fun}, timeout)
  end

+  @doc """
+  Updates the agent state.
+
+  Same as `update/3` but a module, function and args are expected
+  instead of an anonymous function. The state is added as first
+  argument to the given list of args.
+  """
+  @spec update(agent, module, atom, [term], timeout) :: :ok
+  def update(agent, module, fun, args, timeout \\ 5000) do
+    GenServer.call(agent, {:update, {module, fun, args}}, timeout)
+  end
+
  @doc """
  Performs a cast (fire and forget) operation on the agent state.

@@ -213,7 +272,19 @@ defmodule Agent do
  """
  @spec cast(agent, (state -> state)) :: :ok
  def cast(agent, fun) when is_function(fun, 1) do
-    GenServer.cast(agent, fun)
+    GenServer.cast(agent, {:cast, fun})
+  end
+
+  @doc """
+  Performs a cast (fire and forget) operation on the agent state.
+
+  Same as `cast/2` but a module, function and args are expected
+  instead of an anonymous function. The state is added as first
+  argument to the given list of args.
+  """
+  @spec cast(agent, module, atom, [term]) :: :ok
+  def cast(agent, module, fun, args) do
+    GenServer.cast(agent, {:cast, {module, fun, args}})
  end

  @doc """
@@ -4,20 +4,20 @@ defmodule Agent.Server do
  use GenServer

  def init(fun) do
-    {:ok, fun.()}
+    {:ok, run(fun, [])}
  end

  def handle_call({:get, fun}, _from, state) do
-    {:reply, fun.(state), state}
+    {:reply, run(fun, [state]), state}
  end

  def handle_call({:get_and_update, fun}, _from, state) do
-    {reply, state} = fun.(state)
+    {reply, state} = run(fun, [state])
    {:reply, reply, state}
  end

  def handle_call({:update, fun}, _from, state) do
-    {:reply, :ok, fun.(state)}
+    {:reply, :ok, run(fun, [state])}
  end

  def handle_call(:stop, _from, state) do
@@ -28,16 +28,16 @@ defmodule Agent.Server do
    super(msg, from, state)
  end

-  def handle_cast(fun, state) when is_function(fun, 1) do
-    {:noreply, fun.(state)}
+  def handle_cast({:cast, fun}, state) do
+    {:noreply, run(fun, [state])}
  end

  def handle_cast(msg, state) do
    super(msg, state)
  end

-  def code_change(_old, state, { m, f, a }) do
-    {:ok, apply(m, f, [state|a])}
+  def code_change(_old, state, fun) do
+    {:ok, run(fun, [state])}
  end

  def terminate(_reason, _state) do
@@ -50,4 +50,7 @@ defmodule Agent.Server do
    end
    :ok
  end
+
+  defp run({m, f, a}, extra), do: apply(m, f, extra ++ a)
+  defp run(fun, extra), do: apply(fun, extra)
 end
@@ -201,7 +201,7 @@ defmodule Application do
  `:applications` in the `.app` file in case they were not previously
  started.
  """
-  @spec ensure_all_started(app, start_type) :: {:ok, [app]} | {:error, term}
+  @spec ensure_all_started(app, start_type) :: {:ok, [app]} | {:error, {app, term}}
  def ensure_all_started(app, type \\ :temporary) when is_atom(app) do
    :application.ensure_all_started(app, type)
  end
@@ -322,7 +322,7 @@ defmodule Application do

  @doc """
  Formats the error reason returned by `start/2`,
-  `ensure_started/2, `stop/1`, `load/1` and `unload/1`,
+  `ensure_started/2`, `stop/1`, `load/1` and `unload/1`,
  returns a string.
  """
  @spec format_error(any) :: String.t
@@ -499,7 +499,7 @@ defmodule Base do
  defp do_encode64(<<>>, _), do: <<>>
  defp do_encode64(data, enc) do
    split =  3 * div(byte_size(data), 3)
-    <<main::[size(split), binary], rest::binary>> = data
+    <<main::size(split)-binary, rest::binary>> = data
    main = for <<c::6 <- main>>, into: <<>>, do: <<enc.(c)::8>>
    case rest do
      <<c1::6, c2::6, c3::4>> ->
@@ -514,7 +514,7 @@ defmodule Base do
  defp do_decode64(<<>>, _), do: <<>>
  defp do_decode64(string, dec) when rem(byte_size(string), 4) == 0 do
    split = byte_size(string) - 4
-    <<main::[size(split), binary], rest::binary>> = string
+    <<main::size(split)-binary, rest::binary>> = string
    main = for <<c::8 <- main>>, into: <<>>, do: <<dec.(c)::6>>
    case rest do
      <<c1::8, c2::8, ?=, ?=>> ->
@@ -534,7 +534,7 @@ defmodule Base do
  defp do_encode32(<<>>, _), do: <<>>
  defp do_encode32(data, enc) do
    split =  5 * div(byte_size(data), 5)
-    <<main::[size(split), binary], rest::binary>> = data
+    <<main::size(split)-binary, rest::binary>> = data
    main = for <<c::5 <- main>>, into: <<>>, do: <<enc.(c)::8>>
    case rest do
      <<c1::5, c2::5, c3::5, c4::5, c5::5, c6::5, c7::2>> ->
@@ -561,7 +561,7 @@ defmodule Base do
  defp do_decode32(<<>>, _), do: <<>>
  defp do_decode32(string, dec) when rem(byte_size(string), 8) == 0 do
    split = byte_size(string) - 8
-    <<main::[size(split), binary], rest::binary>> = string
+    <<main::size(split)-binary, rest::binary>> = string
    main = for <<c::8 <- main>>, into: <<>>, do: <<dec.(c)::5>>
    case rest do
      <<c1::8, c2::8, ?=, ?=, ?=, ?=, ?=, ?=>> ->
@@ -51,6 +51,14 @@ defmodule Code do
    :code.del_path(to_char_list(Path.expand path))
  end

+  @doc false
+  def readd_paths() do
+    {pa, pz} = :elixir_code_server.call(:paths)
+    :code.add_pathsa(pa)
+    :code.add_pathsz(pz)
+    :ok
+  end
+
  @doc """
  Evaluate the contents given by `string`.

@@ -243,7 +251,7 @@ defmodule Code do
  Accepts `relative_to` as an argument to tell where the file is located.

  While `load_file` loads a file and returns the loaded modules and their
-  byte code, `eval_file` simply evalutes the file contents and returns the
+  byte code, `eval_file` simply evaluates the file contents and returns the
  evaluation result and its bindings.
  """
  def eval_file(file, relative_to \\ nil) do
@@ -308,7 +316,7 @@ defmodule Code do
  Check `compiler_options/1` for more information.
  """
  def compiler_options do
-    :elixir_code_server.call :compiler_options
+    :elixir_config.get :compiler_options
  end

  @doc """
@@ -347,7 +355,8 @@ defmodule Code do
      bad = bad |> Keyword.keys |> Enum.join(", ")
      raise ArgumentError, message: "unknown compiler options: #{bad}"
    end
-    :elixir_code_server.cast {:compiler_options, opts}
+    update = &:orddict.merge(fn(_, _, value) -> value end, &1, opts)
+    :elixir_config.update :compiler_options, update
  end

  @doc """
@@ -8,12 +8,6 @@ defprotocol Collectable do
      iex> Enum.into([a: 1, b: 2], %{})
      %{a: 1, b: 2}

-  If a collection implements both `Enumerable` and `Collectable`, both
-  operations can be combined with `Enum.traverse/2`:
-
-      iex> Enum.traverse(%{a: 1, b: 2}, fn {k, v} -> {k, v * 2} end)
-      %{a: 2, b: 4}
-
  ## Why Collectable?

  The `Enumerable` protocol is useful to take values out of a collection.
@@ -27,25 +21,13 @@ defprotocol Collectable do
  shape where just the range limits are stored.

  The `Collectable` module was designed to fill the gap left by the
-  `Enumerable` protocol. It provides two functions: `into/1` and `empty/1`.
-
-  `into/1` can be seen as the opposite of `Enumerable.reduce/3`. If
-  `Enumerable` is about taking values out, `Collectable.into/1` is about
-  collecting those values into a structure.
-
-  `empty/1` receives a collectable and returns an empty version of the
-  same collectable. By combining the enumerable functionality with `into/1`
-  and `empty/1`, one can, for example, implement a traversal mechanism.
+  `Enumerable` protocol. `into/1` can be seen as the opposite of
+  `Enumerable.reduce/3`. If `Enumerable` is about taking values out,
+  `Collectable.into/1` is about collecting those values into a structure.
  """

  @type command :: {:cont, term} | :done | :halt

-  @doc """
-  Receives a collectable structure and returns an empty one.
-  """
-  @spec empty(t) :: t
-  def empty(collectable)
-
  @doc """
  Returns a function that collects values alongside
  the initial accumulation value.
@@ -65,10 +47,6 @@ defprotocol Collectable do
 end

 defimpl Collectable, for: List do
-  def empty(_list) do
-    []
-  end
-
  def into(original) do
    {[], fn
      list, {:cont, x} -> [x|list]
@@ -79,34 +57,16 @@ defimpl Collectable, for: List do
 end

 defimpl Collectable, for: BitString do
-  def empty(_bitstring) do
-    ""
-  end
-
  def into(original) do
    {original, fn
-      bitstring, {:cont, x} -> <<bitstring :: bits, x :: bits>>
-      bitstring, :done -> bitstring
+      acc, {:cont, x} when is_bitstring(x) -> [acc|x]
+      acc, :done -> IO.iodata_to_binary(acc)
      _, :halt -> :ok
    end}
  end
 end

-defimpl Collectable, for: Function do
-  def empty(function) do
-    function
-  end
-
-  def into(function) do
-    {function, function}
-  end
-end
-
 defimpl Collectable, for: Map do
-  def empty(_map) do
-    %{}
-  end
-
  def into(original) do
    {original, fn
      map, {:cont, {k, v}} -> :maps.put(k, v, map)
@@ -288,8 +288,8 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> Enum.sort(Dict.keys(d))
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> Enum.sort(Dict.keys(dict))
      [:a,:b]

  """
@@ -304,8 +304,8 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> Enum.sort(Dict.values(d))
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> Enum.sort(Dict.values(dict))
      [1,2]

  """
@@ -319,8 +319,8 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> Dict.size(d)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> Dict.size(dict)
      2

  """
@@ -334,10 +334,10 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1], dict_impl.new)
-      iex> Dict.has_key?(d, :a)
+      iex> dict = Enum.into([a: 1], dict_impl.new)
+      iex> Dict.has_key?(dict, :a)
      true
-      iex> Dict.has_key?(d, :b)
+      iex> Dict.has_key?(dict, :b)
      false

  """
@@ -352,12 +352,12 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1], dict_impl.new)
-      iex> Dict.get(d, :a)
+      iex> dict = Enum.into([a: 1], dict_impl.new)
+      iex> Dict.get(dict, :a)
      1
-      iex> Dict.get(d, :b)
+      iex> Dict.get(dict, :b)
      nil
-      iex> Dict.get(d, :b, 3)
+      iex> Dict.get(dict, :b, 3)
      3
  """
  @spec get(t, key, value) :: value
@@ -371,10 +371,10 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1], dict_impl.new)
-      iex> Dict.fetch(d, :a)
+      iex> dict = Enum.into([a: 1], dict_impl.new)
+      iex> Dict.fetch(dict, :a)
      {:ok, 1}
-      iex> Dict.fetch(d, :b)
+      iex> Dict.fetch(dict, :b)
      :error

  """
@@ -389,8 +389,8 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1], dict_impl.new)
-      iex> Dict.fetch!(d, :a)
+      iex> dict = Enum.into([a: 1], dict_impl.new)
+      iex> Dict.fetch!(dict, :a)
      1

  """
@@ -405,9 +405,9 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.put(d, :a, 3)
-      iex> Dict.get(d, :a)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.put(dict, :a, 3)
+      iex> Dict.get(dict, :a)
      3

  """
@@ -421,9 +421,9 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.put_new(d, :a, 3)
-      iex> Dict.get(d, :a)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.put_new(dict, :a, 3)
+      iex> Dict.get(dict, :a)
      1

  """
@@ -438,13 +438,13 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.delete(d, :a)
-      iex> Dict.get(d, :a)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.delete(dict, :a)
+      iex> Dict.get(dict, :a)
      nil

-      iex> d = Enum.into([b: 2], dict_impl.new)
-      iex> Dict.delete(d, :a) == d
+      iex> dict = Enum.into([b: 2], dict_impl.new)
+      iex> Dict.delete(dict, :a) == dict
      true

  """
@@ -454,10 +454,10 @@ defmodule Dict do
  end

  @doc """
-  Merges the dict `b` into dict `a`.
+  Merges the dict `dict2` into dict `dict1`.

-  If one of the dict `b` entries already exists in the `dict`,
-  the functions in entries in `b` have higher precedence unless a
+  If one of the `dict2` entries already exists in `dict1`, the
+  functions in entries in `dict2` have higher precedence unless a
  function is given to resolve conflicts.

  Notice this function is polymorphic as it merges dicts of any
@@ -466,18 +466,18 @@ defmodule Dict do

  ## Examples

-      iex> d1 = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d2 = Enum.into([a: 3, d: 4], dict_impl.new)
-      iex> d = Dict.merge(d1, d2)
-      iex> [a: Dict.get(d, :a), b: Dict.get(d, :b), d: Dict.get(d, :d)]
+      iex> dict1 = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict2 = Enum.into([a: 3, d: 4], dict_impl.new)
+      iex> dict = Dict.merge(dict1, dict2)
+      iex> [a: Dict.get(dict, :a), b: Dict.get(dict, :b), d: Dict.get(dict, :d)]
      [a: 3, b: 2, d: 4]

-      iex> d1 = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d2 = Enum.into([a: 3, d: 4], dict_impl.new)
-      iex> d = Dict.merge(d1, d2, fn(_k, v1, v2) ->
+      iex> dict1 = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict2 = Enum.into([a: 3, d: 4], dict_impl.new)
+      iex> dict = Dict.merge(dict1, dict2, fn(_k, v1, v2) ->
      ...>   v1 + v2
      ...> end)
-      iex> [a: Dict.get(d, :a), b: Dict.get(d, :b), d: Dict.get(d, :d)]
+      iex> [a: Dict.get(dict, :a), b: Dict.get(dict, :b), d: Dict.get(dict, :d)]
      [a: 4, b: 2, d: 4]

  """
@@ -502,18 +502,18 @@ defmodule Dict do
  ## Examples

      iex> dict = Enum.into([a: 1], dict_impl.new)
-      iex> {v, d} = Dict.pop dict, :a
-      iex> {v, Enum.sort(d)}
+      iex> {v, dict} = Dict.pop dict, :a
+      iex> {v, Enum.sort(dict)}
      {1,[]}

      iex> dict = Enum.into([a: 1], dict_impl.new)
-      iex> {v, d} = Dict.pop dict, :b
-      iex> {v, Enum.sort(d)}
+      iex> {v, dict} = Dict.pop dict, :b
+      iex> {v, Enum.sort(dict)}
      {nil,[a: 1]}

      iex> dict = Enum.into([a: 1], dict_impl.new)
-      iex> {v, d} = Dict.pop dict, :b, 3
-      iex> {v, Enum.sort(d)}
+      iex> {v, dict} = Dict.pop dict, :b, 3
+      iex> {v, Enum.sort(dict)}
      {3,[a: 1]}

  """
@@ -528,9 +528,9 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.update!(d, :a, fn(val) -> -val end)
-      iex> Dict.get(d, :a)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.update!(dict, :a, fn(val) -> -val end)
+      iex> Dict.get(dict, :a)
      -1

  """
@@ -546,9 +546,9 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.update(d, :c, 3, fn(val) -> -val end)
-      iex> Dict.get(d, :c)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.update(dict, :c, 3, fn(val) -> -val end)
+      iex> Dict.get(dict, :c)
      3

  """
@@ -566,19 +566,19 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2, c: 3, d: 4], dict_impl.new)
-      iex> {d1, d2} = Dict.split(d, [:a, :c, :e])
-      iex> {Dict.to_list(d1) |> Enum.sort, Dict.to_list(d2) |> Enum.sort}
+      iex> dict = Enum.into([a: 1, b: 2, c: 3, d: 4], dict_impl.new)
+      iex> {dict1, dict2} = Dict.split(dict, [:a, :c, :e])
+      iex> {Dict.to_list(dict1) |> Enum.sort, Dict.to_list(dict2) |> Enum.sort}
      {[a: 1, c: 3], [b: 2, d: 4]}

-      iex> d = Enum.into([], dict_impl.new)
-      iex> {d1, d2} = Dict.split(d, [:a, :c])
-      iex> {Dict.to_list(d1), Dict.to_list(d2)}
+      iex> dict = Enum.into([], dict_impl.new)
+      iex> {dict1, dict2} = Dict.split(dict, [:a, :c])
+      iex> {Dict.to_list(dict1), Dict.to_list(dict2)}
      {[], []}

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> {d1, d2} = Dict.split(d, [:a, :b, :c])
-      iex> {Dict.to_list(d1) |> Enum.sort, Dict.to_list(d2)}
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> {dict1, dict2} = Dict.split(dict, [:a, :b, :c])
+      iex> {Dict.to_list(dict1) |> Enum.sort, Dict.to_list(dict2)}
      {[a: 1, b: 2], []}

  """
@@ -593,14 +593,14 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.drop(d, [:a, :c, :d])
-      iex> Dict.to_list(d)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.drop(dict, [:a, :c, :d])
+      iex> Dict.to_list(dict)
      [b: 2]

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.drop(d, [:c, :d])
-      iex> Dict.to_list(d) |> Enum.sort
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.drop(dict, [:c, :d])
+      iex> Dict.to_list(dict) |> Enum.sort
      [a: 1, b: 2]

  """
@@ -616,12 +616,12 @@ defmodule Dict do

  ## Examples

-      iex> d = Enum.into([a: 1, b: 2], dict_impl.new)
-      iex> d = Dict.take(d, [:a, :c, :d])
-      iex> Dict.to_list(d)
+      iex> dict = Enum.into([a: 1, b: 2], dict_impl.new)
+      iex> dict = Dict.take(dict, [:a, :c, :d])
+      iex> Dict.to_list(dict)
      [a: 1]
-      iex> d = Dict.take(d, [:c, :d])
-      iex> Dict.to_list(d)
+      iex> dict = Dict.take(dict, [:c, :d])
+      iex> Dict.to_list(dict)
      []

  """
@@ -645,14 +645,14 @@ defmodule Dict do

  ## Examples

-      iex> a = Enum.into([a: 2, b: 3, f: 5, c: 123], dict_impl.new)
-      iex> b = [a: 2, b: 3, f: 5, c: 123]
-      iex> Dict.equal?(a, b)
+      iex> dict1 = Enum.into([a: 2, b: 3, f: 5, c: 123], dict_impl.new)
+      iex> dict2 = [a: 2, b: 3, f: 5, c: 123]
+      iex> Dict.equal?(dict1, dict2)
      true

-      iex> a = Enum.into([a: 2, b: 3, f: 5, c: 123], dict_impl.new)
-      iex> b = []
-      iex> Dict.equal?(a, b)
+      iex> dict1 = Enum.into([a: 2, b: 3, f: 5, c: 123], dict_impl.new)
+      iex> dict2 = []
+      iex> Dict.equal?(dict1, dict2)
      false

  """
@@ -270,8 +270,13 @@ defmodule Enum do

  @doc """
  Finds the element at the given index (zero-based).
+
  Returns `default` if index is out of bounds.

+  Note this operation takes linear time. In order to access
+  the element at index `n`, it will need to traverse `n`
+  previous elements.
+
  ## Examples

      iex> Enum.at([2, 4, 6], 0)
@@ -287,7 +292,6 @@ defmodule Enum do
      :none

  """
-  @spec at(t, integer) :: element | nil
  @spec at(t, integer, default) :: element | default
  def at(collection, n, default \\ nil) do
    case fetch(collection, n) do
@@ -330,7 +334,6 @@ defmodule Enum do
      [[1, 2, 3], [4, 5, 6]]

  """
-  @spec chunk(t, non_neg_integer, non_neg_integer) :: [list]
  @spec chunk(t, non_neg_integer, non_neg_integer, t | nil) :: [list]
  def chunk(coll, n, step, pad \\ nil) when n > 0 and step > 0 do
    limit = :erlang.max(n, step)
@@ -338,7 +341,7 @@ defmodule Enum do
    {_, {acc, {buffer, i}}} =
      Enumerable.reduce(coll, {:cont, {[], {[], 0}}}, R.chunk(n, step, limit))

-    if nil?(pad) || i == 0 do
+    if is_nil(pad) || i == 0 do
      :lists.reverse(acc)
    else
      buffer = :lists.reverse(buffer) ++ take(pad, n - i)
@@ -566,12 +569,17 @@ defmodule Enum do

  @doc """
  Finds the element at the given index (zero-based).
+
  Returns `{:ok, element}` if found, otherwise `:error`.

  A negative index can be passed, which means the collection is
  enumerated once and the index is counted from the end (i.e.
  `-1` fetches the last element).

+  Note this operation takes linear time. In order to access
+  the element at index `n`, it will need to traverse `n`
+  previous elements.
+
  ## Examples

      iex> Enum.fetch([2, 4, 6], 0)
@@ -585,11 +593,11 @@ defmodule Enum do

  """
  @spec fetch(t, integer) :: {:ok, element} | :error
-  def fetch(collection, n) when is_list(collection) and n >= 0 do
+  def fetch(collection, n) when is_list(collection) and is_integer(n) and n >= 0 do
    do_fetch(collection, n)
  end

-  def fetch(collection, n) when n >= 0 do
+  def fetch(collection, n) when is_integer(n) and n >= 0 do
    res =
      Enumerable.reduce(collection, {:cont, 0}, fn(entry, acc) ->
        if acc == n do
@@ -605,15 +613,20 @@ defmodule Enum do
    end
  end

-  def fetch(collection, n) when n < 0 do
+  def fetch(collection, n) when is_integer(n) and n < 0 do
    do_fetch(reverse(collection), abs(n + 1))
  end

  @doc """
  Finds the element at the given index (zero-based).
+
  Raises `OutOfBoundsError` if the given position
  is outside the range of the collection.

+  Note this operation takes linear time. In order to access
+  the element at index `n`, it will need to traverse `n`
+  previous elements.
+
  ## Examples

      iex> Enum.fetch!([2, 4, 6], 0)
@@ -689,7 +702,6 @@ defmodule Enum do
      3

  """
-  @spec find(t, (element -> any)) :: element | nil
  @spec find(t, default, (element -> any)) :: element | default
  def find(collection, ifnone \\ nil, fun)

@@ -716,7 +728,6 @@ defmodule Enum do
      true

  """
-  @spec find_value(t, (element -> any)) :: any | :nil
  @spec find_value(t, any, (element -> any)) :: any | :nil
  def find_value(collection, ifnone \\ nil, fun)

@@ -931,7 +942,6 @@ defmodule Enum do
      "1 = 2 = 3"

  """
-  @spec join(t) :: String.t
  @spec join(t, String.t) :: String.t
  def join(collection, joiner \\ "")

@@ -990,7 +1000,6 @@ defmodule Enum do
      "2 = 4 = 6"

  """
-  @spec map_join(t, (element -> any)) :: String.t
  @spec map_join(t, String.t, (element -> any)) :: String.t
  def map_join(collection, joiner \\ "", mapper)

@@ -1252,6 +1261,15 @@ defmodule Enum do
    :lists.foldl(fun, acc, collection)
  end

+  def reduce(%{__struct__: _} = collection, acc, fun) do
+    Enumerable.reduce(collection, {:cont, acc},
+                      fn x, acc -> {:cont, fun.(x, acc)} end) |> elem(1)
+  end
+
+  def reduce(%{} = collection, acc, fun) do
+    :maps.fold(fn k, v, acc -> fun.({k, v}, acc) end, acc, collection)
+  end
+
  def reduce(collection, acc, fun) do
    Enumerable.reduce(collection, {:cont, acc},
                      fn x, acc -> {:cont, fun.(x, acc)} end) |> elem(1)
@@ -1396,7 +1414,7 @@ defmodule Enum do
  result. For example, one could do the following to set a seed
  dynamically:

-      :random.seed(:erlang.now)
+      :random.seed(:os.timestamp)

  ## Examples

@@ -1568,6 +1586,46 @@ defmodule Enum do
    reduce(collection, [], &sort_reducer(&1, &2, fun)) |> sort_terminator(fun)
  end

+  @doc """
+  Sorts the mapped results of the `collection` according to the `sorter` function.
+
+  This function maps each element of the collection using the `mapper`
+  function.  The collection is then sorted by the mapped elements using the
+  `sorter` function, which defaults to `<=/2`
+
+  `sort_by/3` differs from `sort/2` in that it only calculates the comparison
+  value for each element in the collection once instead of once for each
+  element in each comparison.  If the same function is being called on both
+  element, it's also more compact to use `sort_by/3`.
+
+  This technique is also known as a
+  [Schwartzian Transform](https://en.wikipedia.org/wiki/Schwartzian_transform),
+  or the Lisp decorate-sort-undecorate idiom as the `mapper` is decorating the
+  original `collection`, then `sorter` is sorting the decorations, and finally
+  the `collection` is being undecorated so only the original elements remain,
+  but now in sorted order.
+
+  ## Examples
+
+  Using the default `sorter` of `<=/2`:
+
+      iex> Enum.sort_by ["some", "kind", "of", "monster"], &byte_size/1
+      ["of", "some", "kind", "monster"]
+
+  Using a custom `sorter` to override the order:
+
+      iex> Enum.sort_by ["some", "kind", "of", "monster"], &byte_size/1, &>=/2
+      ["monster", "some", "kind", "of"]
+
+  """
+  @spec sort_by(t, (element -> mapped_element), (mapped_element, mapped_element -> boolean)) :: list when mapped_element: element
+  def sort_by(collection, mapper, sorter \\ &<=/2) do
+    collection 
+    |> map(&{&1, mapper.(&1)})
+    |> sort(&sorter.(elem(&1, 1), elem(&2, 1)))
+    |> map(&elem(&1, 0))
+  end
+
  @doc """
  Splits the enumerable into two collections, leaving `count`
  elements in the first one. If `count` is a negative number,
@@ -1673,23 +1731,23 @@ defmodule Enum do
    []
  end

-  def take(collection, count) when is_list(collection) and count > 0 do
+  def take(collection, count) when is_list(collection) and is_integer(count) and count > 0 do
    do_take(collection, count)
  end

-  def take(collection, count) when count > 0 do
+  def take(collection, count) when count > 0 and is_integer(count) do
    {_, {res, _}} =
      Enumerable.reduce(collection, {:cont, {[], count}}, fn(entry, {list, count}) ->
-        if count > 1 do
-          {:cont, {[entry|list], count - 1}}
-        else
-          {:halt, {[entry|list], count}}
+        case count do
+          0 -> {:halt, {list, count}}
+          1 -> {:halt, {[entry|list], count - 1}}
+          _ -> {:cont, {[entry|list], count - 1}}
        end
      end)
    :lists.reverse(res)
  end

-  def take(collection, count) when count < 0 do
+  def take(collection, count) when count < 0 and is_integer(count) do
    Stream.take(collection, count).({:cont, []}, &{:cont, [&1|&2]})
    |> elem(1) |> :lists.reverse
  end
@@ -1749,27 +1807,6 @@ defmodule Enum do
    reverse(collection) |> :lists.reverse
  end

-
-  @doc """
-  Traverses the given enumerable keeping its shape.
-
-  It also expects the enumerable to implement the `Collectable` protocol.
-
-  ## Examples
-
-      iex> Enum.traverse(%{a: 1, b: 2}, fn {k, v} -> {k, v * 2} end)
-      %{a: 2, b: 4}
-
-  """
-  @spec traverse(Enumerable.t, (term -> term)) :: Collectable.t
-  def traverse(collection, transform) when is_list(collection) do
-    :lists.map(transform, collection)
-  end
-
-  def traverse(collection, transform) do
-    into(collection, Collectable.empty(collection), transform)
-  end
-
  @doc """
  Enumerates the collection, removing all duplicated items.

@@ -5,16 +5,16 @@ defmodule Exception do
  Note that stacktraces in Elixir are updated on throw,
  errors and exits. For example, at any given moment,
  `System.stacktrace` will return the stacktrace for the
-  last throw/error/exit that ocurred in the current process.
+  last throw/error/exit that occurred in the current process.

  Do not rely on the particular format returned by the `format`
  functions in this module. They may be changed in future releases
  in order to better suit Elixir's tool chain. In other words,
-  by using the functions in this module it is guarantee you will
+  by using the functions in this module it is guaranteed you will
  format exceptions as in the current Elixir version being used.
  """

-  @typedoc "The exception type (as generated by defexception)"
+  @typedoc "The exception type"
  @type t :: %{__struct__: module, __exception__: true}

  @typedoc "The kind handled by formatting functions"
@@ -482,6 +482,7 @@ end
 defmodule RuntimeError do
  defexception message: "runtime error"

+  @spec exception(String.t) :: Exception.t
  def exception(msg) when is_binary(msg) do
    %RuntimeError{message: msg}
  end
@@ -494,6 +495,7 @@ end
 defmodule ArgumentError do
  defexception message: "argument error"

+  @spec exception(String.t) :: Exception.t
  def exception(msg) when is_binary(msg) do
    %ArgumentError{message: msg}
  end
@@ -562,6 +564,14 @@ defmodule BadStructError do
  end
 end

+defmodule BadMapError do
+  defexception [term: nil]
+
+  def message(exception) do
+    "expected a map, got: #{inspect(exception.term)}"
+  end
+end
+
 defmodule MatchError do
  defexception [term: nil]

@@ -611,12 +621,17 @@ defmodule BadArityError do
 end

 defmodule UndefinedFunctionError do
-  defexception [module: nil, function: nil, arity: nil]
+  defexception [module: nil, function: nil, arity: nil, self: false]

-  def message(exception) do
-    if exception.function do
-      formatted = Exception.format_mfa exception.module, exception.function, exception.arity
-      "undefined function: #{formatted}"
+  def message(%{function: function, module: module, arity: arity, self: self}) do
+    if function do
+      formatted = Exception.format_mfa module, function, arity
+      suffix = if self or is_nil(module) or :code.is_loaded(module) do
+        ""
+      else
+        " (module #{inspect module} is not available)"
+      end
+      "undefined function: #{formatted}" <> suffix
    else
      "undefined function"
    end
@@ -662,7 +677,12 @@ defmodule KeyError do
  defexception key: nil, term: nil

  def message(exception) do
-    "key #{inspect exception.key} not found in: #{inspect exception.term}"
+    msg = "key #{inspect exception.key} not found"
+    if exception.term != nil do
+      msg <> " in: #{inspect exception.term}"
+    else
+      msg
+    end
  end
 end

@@ -761,6 +781,20 @@ defmodule ErlangError do
    %MatchError{term: term}
  end

+  def normalize({:badmap, term}, _stacktrace) do
+    %BadMapError{term: term}
+  end
+
+  def normalize({:badkey, key}, stacktrace) do
+    term =
+      case stacktrace || :erlang.get_stacktrace do
+        [{:maps, :update, [_, _, map], _}|_] -> map
+        [{:maps, :get, [_, map], _}|_] -> map
+        _ -> nil
+      end
+    %KeyError{key: key, term: term}
+  end
+
  def normalize({:case_clause, term}, _stacktrace) do
    %CaseClauseError{term: term}
  end
@@ -770,8 +804,9 @@ defmodule ErlangError do
  end

  def normalize(:undef, stacktrace) do
-    {mod, fun, arity} = from_stacktrace(stacktrace || :erlang.get_stacktrace)
-    %UndefinedFunctionError{module: mod, function: fun, arity: arity}
+    stacktrace = stacktrace || :erlang.get_stacktrace
+    {mod, fun, arity} = from_stacktrace(stacktrace)
+    %UndefinedFunctionError{module: mod, function: fun, arity: arity, self: from_self(stacktrace)}
  end

  def normalize(:function_clause, stacktrace) do
@@ -798,4 +833,7 @@ defmodule ErlangError do
  defp from_stacktrace(_) do
    {nil, nil, nil}
  end
+
+  defp from_self([{module, _, _, _}, {module, _, _, _}|_]), do: true
+  defp from_self(_), do: false
 end
@@ -75,6 +75,12 @@ defmodule File do
  @type posix :: :file.posix()
  @type io_device :: :file.io_device()
  @type stat_options :: [time: :local | :universal | :posix]
+  @type mode :: :append | :binary | :compressed | :delayed_write | :exclusive |
+    :raw | :read | :read_ahead | :sync | :write |
+    {:encoding , :latin1 | :unicode | :utf16 | :utf32 | :utf8 |
+      {:utf16, :big | :little} | {:utf32, :big | :little}} |
+    {:read_ahead, pos_integer} |
+    {:delayed_write, non_neg_integer, non_neg_integer}

  @doc """
  Returns `true` if the path is a regular file.
@@ -308,11 +314,15 @@ defmodule File do
  def touch(path, time \\ :calendar.local_time) do
    path = IO.chardata_to_string(path)
    case F.change_time(path, time) do
-      {:error, :enoent} ->
-        write(path, "")
-        F.change_time(path, time)
-      other ->
-        other
+      {:error, :enoent} -> touch_new(path, time)
+      other -> other
+    end
+  end
+
+  defp touch_new(path, time) do
+    case write(path, "", [:append]) do
+      :ok -> F.change_time(path, time)
+      {:error, _reason} = error -> error
    end
  end

@@ -548,7 +558,8 @@ defmodule File do
        [dest|acc]
      {:error, :eexist} ->
        if callback.(src, dest) do
-          rm(dest)
+          # If rm/1 fails, copy/2 will fail
+          _ = rm(dest)
          case copy(src, dest) do
            {:ok, _} ->
              copy_file_mode!(src, dest)
@@ -569,7 +580,8 @@ defmodule File do
        [dest|acc]
      {:error, :eexist} ->
        if callback.(src, dest) do
-          rm(dest)
+          # If rm/1 fails, iF.make_symlink/2 will fail
+          _ = rm(dest)
          case F.make_symlink(link, dest) do
            :ok -> [dest|acc]
            {:error, reason} -> {:error, reason, src}
@@ -606,7 +618,7 @@ defmodule File do

  Check `File.open/2` for other available options.
  """
-  @spec write(Path.t, iodata, list) :: :ok | {:error, posix}
+  @spec write(Path.t, iodata, [mode]) :: :ok | {:error, posix}
  def write(path, content, modes \\ []) do
    F.write_file(IO.chardata_to_string(path), content, modes)
  end
@@ -614,7 +626,7 @@ defmodule File do
  @doc """
  Same as `write/3` but raises an exception if it fails, returns `:ok` otherwise.
  """
-  @spec write!(Path.t, iodata, list) :: :ok | no_return
+  @spec write!(Path.t, iodata, [mode]) :: :ok | no_return
  def write!(path, content, modes \\ []) do
    path = IO.chardata_to_string(path)
    case F.write_file(path, content, modes) do
@@ -665,14 +677,20 @@ defmodule File do
    if match? {:win32, _}, :os.type do
      case F.read_file_info(IO.chardata_to_string(path)) do
        {:ok, file_info} when elem(file_info, 3) in [:read, :none] ->
-          File.chmod(path, (elem(file_info, 7) + 0200))
-          F.delete(path)
+          change_mode_windows(path, file_info)
        _ ->
          nil
      end
    end
  end

+  defp change_mode_windows(path, file_info) do
+    case File.chmod(path, (elem(file_info, 7) + 0o200)) do
+      :ok -> F.delete(path)
+      {:error, _reason} = error -> error
+    end
+  end
+
  @doc """
  Same as `rm/1`, but raises an exception in case of failure. Otherwise `:ok`.
  """
@@ -890,7 +908,8 @@ defmodule File do
      File.close(file)

  """
-  @spec open(Path.t, list) :: {:ok, io_device} | {:error, posix}
+  @spec open(Path.t, [mode | :ram]) :: {:ok, io_device} | {:error, posix}
+  @spec open(Path.t, (io_device -> res)) :: {:ok, res} | {:error, posix} when res: var
  def open(path, modes \\ [])

  def open(path, modes) when is_list(modes) do
@@ -923,7 +942,7 @@ defmodule File do
      end)

  """
-  @spec open(Path.t, list, (io_device -> res)) :: {:ok, res} | {:error, posix} when res: var
+  @spec open(Path.t, [mode | :ram], (io_device -> res)) :: {:ok, res} | {:error, posix} when res: var
  def open(path, modes, function) do
    case open(path, modes) do
      {:ok, device} ->
@@ -941,7 +960,7 @@ defmodule File do

  Returns the `io_device` otherwise.
  """
-  @spec open!(Path.t, list) :: io_device | no_return
+  @spec open!(Path.t, [mode]) :: io_device | no_return
  def open!(path, modes \\ []) do
    path = IO.chardata_to_string(path)
    case open(path, modes) do
@@ -956,7 +975,7 @@ defmodule File do

  Returns the function result otherwise.
  """
-  @spec open!(Path.t, list, (io_device -> res)) :: res | no_return when res: var
+  @spec open!(Path.t, [mode | :ram], (io_device -> res)) :: res | no_return when res: var
  def open!(path, modes, function) do
    path = IO.chardata_to_string(path)
    case open(path, modes, function) do
@@ -977,18 +996,27 @@ defmodule File do
  @spec cwd() :: {:ok, binary} | {:error, posix}
  def cwd() do
    case F.get_cwd do
-      {:ok, base} -> {:ok, IO.chardata_to_string(base)}
+      {:ok, base} -> {:ok, IO.chardata_to_string(fix_drive_letter(base))}
      {:error, _} = error -> error
    end
  end

+  defp fix_drive_letter([l, ?:, ?/ | rest] = original) when l in ?A..?Z do
+    case :os.type() do
+      {:win32, _} -> [l+?a-?A, ?:, ?/ | rest]
+      _ -> original
+    end
+  end
+
+  defp fix_drive_letter(original), do: original
+
  @doc """
  The same as `cwd/0`, but raises an exception if it fails.
  """
  @spec cwd!() :: binary | no_return
  def cwd!() do
-    case F.get_cwd do
-      {:ok, cwd} -> IO.chardata_to_string(cwd)
+    case cwd() do
+      {:ok, cwd} -> cwd
      {:error, reason} ->
          raise File.Error, reason: reason, action: "get current working directory"
    end
@@ -1112,7 +1140,7 @@ defmodule File do
  Returns `:ok` on success, or `{:error, reason}`
  on failure.
  """
-  @spec chmod(Path.t, integer) :: :ok | {:error, posix}
+  @spec chmod(Path.t, non_neg_integer) :: :ok | {:error, posix}
  def chmod(path, mode) do
    F.change_mode(IO.chardata_to_string(path), mode)
  end
@@ -1120,7 +1148,7 @@ defmodule File do
  @doc """
  Same as `chmod/2`, but raises an exception in case of failure. Otherwise `:ok`.
  """
-  @spec chmod!(Path.t, integer) :: :ok | no_return
+  @spec chmod!(Path.t, non_neg_integer) :: :ok | no_return
  def chmod!(path, mode) do
    path = IO.chardata_to_string(path)
    case chmod(path, mode) do
@@ -1135,7 +1163,7 @@ defmodule File do
  for a given `file`. Returns `:ok` on success, or
  `{:error, reason}` on failure.
  """
-  @spec chgrp(Path.t, integer) :: :ok | {:error, posix}
+  @spec chgrp(Path.t, non_neg_integer) :: :ok | {:error, posix}
  def chgrp(path, gid) do
    F.change_group(IO.chardata_to_string(path), gid)
  end
@@ -1143,7 +1171,7 @@ defmodule File do
  @doc """
  Same as `chgrp/2`, but raises an exception in case of failure. Otherwise `:ok`.
  """
-  @spec chgrp!(Path.t, integer) :: :ok | no_return
+  @spec chgrp!(Path.t, non_neg_integer) :: :ok | no_return
  def chgrp!(path, gid) do
    path = IO.chardata_to_string(path)
    case chgrp(path, gid) do
@@ -1158,7 +1186,7 @@ defmodule File do
  for a given `file`. Returns `:ok` on success,
  or `{:error, reason}` on failure.
  """
-  @spec chown(Path.t, integer) :: :ok | {:error, posix}
+  @spec chown(Path.t, non_neg_integer) :: :ok | {:error, posix}
  def chown(path, uid) do
    F.change_owner(IO.chardata_to_string(path), uid)
  end
@@ -1166,7 +1194,7 @@ defmodule File do
  @doc """
  Same as `chown/2`, but raises an exception in case of failure. Otherwise `:ok`.
  """
-  @spec chown!(Path.t, integer) :: :ok | no_return
+  @spec chown!(Path.t, non_neg_integer) :: :ok | no_return
  def chown!(path, uid) do
    path = IO.chardata_to_string(path)
    case chown(path, uid) do
@@ -57,6 +57,7 @@ defmodule File.Stat do
  pairs  = :lists.zip(keys, vals)

  defstruct keys
+  @type t :: %__MODULE__{}

  @doc """
  Converts a `File.Stat` struct to a `:file_info` record.
@@ -13,6 +13,8 @@ defmodule File.Stream do

  defstruct path: nil, modes: [], line_or_bytes: :line, raw: true

+  @type t :: %__MODULE__{}
+
  @doc false
  def __build__(path, modes, line_or_bytes) do
    raw = :lists.keyfind(:encoding, 1, modes) == false
@@ -55,10 +57,14 @@ defmodule File.Stream do
            false -> IO.write(device, x)
          end
        :ok, :done ->
-          :file.close(device)
+          # If delayed_write option is used and the last write failed will
+          # MatchError here as {:error, _} is returned.
+          :ok = :file.close(device)
          stream
        :ok, :halt ->
-          :file.close(device)
+          # If delayed_write option is used and the last write failed will
+          # MatchError here as {:error, _} is returned.
+          :ok = :file.close(device)
      end
    end
  end
@@ -1,3 +1,5 @@
+import Kernel, except: [round: 1]
+
 defmodule Float do
  @moduledoc """
  Functions for working with floating point numbers.
@@ -26,130 +28,108 @@ defmodule Float do
  """
  @spec parse(binary) :: {float, binary} | :error
  def parse("-" <> binary) do
-    case parse_unsign(binary) do
+    case parse_unsigned(binary) do
      :error -> :error
      {number, remainder} -> {-number, remainder}
    end
  end

  def parse(binary) do
-    parse_unsign(binary)
+    parse_unsigned(binary)
  end

-  defp parse_unsign("-" <> _), do: :error
-  defp parse_unsign(binary) when is_binary(binary) do
-    case Integer.parse binary do
-      :error -> :error
-      {integer_part, after_integer} -> parse_unsign after_integer, integer_part
-    end
-  end
+  defp parse_unsigned(<<char, rest::binary>>) when char in ?0..?9, do:
+    parse_unsigned(rest, false, false, <<char>>)

-  # Dot followed by digit is required afterwards or we are done
-  defp parse_unsign(<< ?., char, rest :: binary >>, int) when char in ?0..?9 do
-    parse_unsign(rest, char - ?0, 1, int)
-  end
+  defp parse_unsigned(binary) when is_binary(binary), do:
+    :error

-  defp parse_unsign(rest, int) do
-    {:erlang.float(int), rest}
-  end
+  defp parse_unsigned(<<char, rest :: binary>>, dot?, e?, acc) when char in ?0..?9, do:
+    parse_unsigned(rest, dot?, e?, <<acc::binary, char>>)

-  # Handle decimal points
-  defp parse_unsign(<< char, rest :: binary >>, float, decimal, int) when char in ?0..?9 do
-    parse_unsign rest, 10 * float + (char - ?0), decimal + 1, int
-  end
+  defp parse_unsigned(<<?., char, rest :: binary>>, false, false, acc) when char in ?0..?9, do:
+    parse_unsigned(rest, true, false, <<acc::binary, ?., char>>)

-  defp parse_unsign(<< ?e, after_e :: binary >>, float, decimal, int) do
-    case Integer.parse after_e do
-      :error ->
-        # Note we rebuild the binary here instead of breaking it apart at
-        # the function clause because the current approach copies a binary
-        # just on this branch. If we broke it apart in the function clause,
-        # the copy would happen when calling Integer.parse/1.
-        {floatify(int, float, decimal), << ?e, after_e :: binary >>}
-      {exponential, after_exponential} ->
-        {floatify(int, float, decimal, exponential), after_exponential}
-    end
-  end
+  defp parse_unsigned(<<?e, char, rest :: binary>>, dot?, false, acc) when char in ?0..?9, do:
+    parse_unsigned(rest, true, true, <<add_dot(acc, dot?)::binary, ?e, char>>)

-  defp parse_unsign(bitstring, float, decimal, int) do
-    {floatify(int, float, decimal), bitstring}
-  end
+  defp parse_unsigned(<<?e, ?-, char, rest :: binary>>, dot?, false, acc) when char in ?0..?9, do:
+    parse_unsigned(rest, true, true, <<add_dot(acc, dot?)::binary, ?e, ?-, char>>)

-  defp floatify(int, float, decimal, exponential \\ 0) do
-    multiplier = if int < 0, do: -1.0, else: 1.0
+  defp parse_unsigned(rest, dot?, _e?, acc), do:
+    {:erlang.binary_to_float(add_dot(acc, dot?)), rest}

-    # Try to ensure the minimum amount of rounding errors
-    result = multiplier * (abs(int) * :math.pow(10, decimal) + float) * :math.pow(10, exponential - decimal)
-
-    # Try avoiding stuff like this:
-    # iex(1)> 0.0001 * 75
-    # 0.007500000000000001
-    # Due to IEEE 754 floating point standard
-    # http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
-
-    final_decimal_places = decimal - exponential
-    if final_decimal_places > 0 do
-      decimal_power_round = :math.pow(10,  final_decimal_places)
-      trunc(result * decimal_power_round) / decimal_power_round
-    else
-      result
-    end
-  end
+  defp add_dot(acc, true),  do: acc
+  defp add_dot(acc, false), do: acc <> ".0"

  @doc """
  Rounds a float to the largest integer less than or equal to `num`.

+  Floor also accepts a precision to round a floating point value down
+  to an arbitrary number of fractional digits (between 0 and 15).
+
+  This function always returns floats. One may use `Kernel.trunc/1` to
+  truncate the result to an integer afterwards.
+
  ## Examples

-      iex> Float.floor(34)
-      34
-
      iex> Float.floor(34.25)
-      34
+      34.0

      iex> Float.floor(-56.5)
-      -57
+      -57.0
+
+      iex> Float.floor(34.253, 2)
+      34.25

  """
-  @spec floor(float | integer) :: integer
-  def floor(num) when is_integer(num), do: num
-  def floor(num) when is_float(num) do
-    truncated = :erlang.trunc(num)
-    case :erlang.abs(num - truncated) do
-      x when x > 0 and num < 0 -> truncated - 1
-      _ -> truncated
-    end
+  @spec floor(float, 0..15) :: float
+  def floor(number, precision \\ 0) when is_float(number) and precision in 0..15 do
+    power     = power_of_10(precision)
+    number    = number * power
+    truncated = trunc(number)
+    variance  = if number - truncated < 0, do: -1.0, else: 0.0
+    (truncated + variance) / power
  end

  @doc """
  Rounds a float to the largest integer greater than or equal to `num`.

+  Ceil also accepts a precision to round a floating point value down to
+  an arbitrary number of fractional digits (between 0 and 15).
+
+  This function always returns floats. One may use `Kernel.trunc/1` to
+  truncate the result to an integer afterwards.
+
  ## Examples

-      iex> Float.ceil(34)
-      34
-
      iex> Float.ceil(34.25)
-      35
+      35.0

      iex> Float.ceil(-56.5)
-      -56
+      -56.0
+
+      iex> Float.ceil(34.253, 2)
+      34.26

  """
-  @spec ceil(float | integer) :: integer
-  def ceil(num) when is_integer(num), do: num
-  def ceil(num) when is_float(num) do
-    truncated = :erlang.trunc(num)
-    case :erlang.abs(num - truncated) do
-      x when x > 0 and num > 0 -> truncated + 1
-      _ -> truncated
-    end
+  @spec ceil(float, 0..15) :: float
+  def ceil(number, precision \\ 0) when is_float(number) and precision in 0..15 do
+    power     = power_of_10(precision)
+    number    = number * power
+    truncated = trunc(number)
+    variance  = if number - truncated > 0, do: 1.0, else: 0.0
+    (truncated + variance) / power
  end

  @doc """
  Rounds a floating point value to an arbitrary number of fractional digits
  (between 0 and 15).

+  This function only accepts floats and returns floats. Use `Kernel.round/1`
+  if you want a function that accepts both floats and integers and always
+  returns an integer.
+
  ## Examples

      iex> Float.round(5.5674, 3)
@@ -165,9 +145,15 @@ defmodule Float do
      -5.568

  """
-  @spec round(float, integer) :: float
-  def round(number, precision) when is_float(number) and is_integer(precision) and precision in 0..15 do
-    Kernel.round(number * :math.pow(10, precision)) / :math.pow(10, precision)
+  @spec round(float, 0..15) :: float
+  def round(number, precision \\ 0) when is_float(number) and precision in 0..15 do
+    power = power_of_10(precision)
+    Kernel.round(number * power) / power
+  end
+
+  Enum.reduce 0..15, 1, fn x, acc ->
+    defp power_of_10(unquote(x)), do: unquote(acc)
+    acc * 10
  end

  @doc """
@@ -0,0 +1,168 @@
+defmodule GenEvent.Stream do
+  @moduledoc """
+  Defines a `GenEvent` stream.
+
+  This is a struct returned by `stream/2`. The struct is public and
+  contains the following fields:
+
+    * `:manager`  - the manager reference given to `GenEvent.stream/2`
+    * `:timeout`  - the timeout in between events, defaults to `:infinity`
+
+  """
+  defstruct manager: nil, timeout: :infinity
+
+  @type t :: %__MODULE__{
+               manager: GenEvent.manager,
+               timeout: timeout}
+
+  @doc false
+  def init({_pid, _ref} = state) do
+    {:ok, state}
+  end
+
+  @doc false
+  def handle_event(event, _state) do
+    exit({:bad_event, event})
+  end
+
+  @doc false
+  def handle_call(msg, _state) do
+    exit({:bad_call, msg})
+  end
+
+  @doc false
+  def handle_info(_msg, state) do
+    {:ok, state}
+  end
+
+  @doc false
+  def terminate(_reason, _state) do
+    :ok
+  end
+
+  @doc false
+  def code_change(_old, state, _extra) do
+    {:ok, state}
+  end
+end
+
+defimpl Enumerable, for: GenEvent.Stream do
+  def reduce(stream, acc, fun) do
+    start_fun = fn() -> start(stream) end
+    next_fun = &next(stream, &1)
+    stop_fun = &stop(stream, &1)
+    Stream.resource(start_fun, next_fun, stop_fun).(acc, wrap_reducer(fun))
+  end
+
+  def count(_stream) do
+    {:error, __MODULE__}
+  end
+
+  def member?(_stream, _item) do
+    {:error, __MODULE__}
+  end
+
+  defp wrap_reducer(fun) do
+    fn
+      {:ack, manager, ref, event}, acc ->
+        send manager, {ref, :ok}
+        fun.(event, acc)
+      {:async, _manager, _ref, event}, acc ->
+        fun.(event, acc)
+      {:sync, manager, ref, event}, acc ->
+        try do
+          fun.(event, acc)
+        after
+          send manager, {ref, :ok}
+        end
+    end
+  end
+
+  defp start(%{manager: manager} = stream) do
+    try do
+      {:ok, {pid, ref}} = :gen.call(manager, self(),
+                                    {:add_process_handler, self(), self()}, :infinity)
+      mon_ref = Process.monitor(pid)
+      {pid, ref, mon_ref}
+    catch
+      :exit, reason -> exit({reason, {__MODULE__, :start, [stream]}})
+    end
+  end
+
+  defp next(%{timeout: timeout} = stream, {pid, ref, mon_ref} = acc) do
+    self = self()
+
+    receive do
+      # Got an async event.
+      {_from, {^pid, ^ref}, {:notify, event}} ->
+        {[{:async, pid, ref, event}], acc}
+
+      # Got a sync event.
+      {_from, {^pid, ^ref}, {:sync_notify, event}} ->
+        {[{:sync, pid, ref, event}], acc}
+
+      # Got an ack event.
+      {_from, {^pid, ^ref}, {:ack_notify, event}} ->
+        {[{:ack, pid, ref, event}], acc}
+
+      # The handler was removed. Stop iteration, resolve the
+      # event later. We need to demonitor now, otherwise DOWN
+      # appears with higher priority in the shutdown process.
+      {:gen_event_EXIT, {^pid, ^ref}, _reason} = event ->
+        Process.demonitor(mon_ref, [:flush])
+        send(self, event)
+        {:halt, {:removed, acc}}
+
+      # The manager died. Stop iteration, resolve the event later.
+      {:DOWN, ^mon_ref, _, _, _} = event ->
+        send(self, event)
+        {:halt, {:removed, acc}}
+    after
+      timeout ->
+        exit({:timeout, {__MODULE__, :next, [stream, acc]}})
+    end
+  end
+
+  # If we reach this branch, we know the handler was already
+  # removed, so we don't trigger a request for doing so.
+  defp stop(stream, {:removed, {pid, ref, mon_ref} = acc}) do
+    case wait_for_handler_removal(pid, ref, mon_ref) do
+      :ok ->
+        flush_events(ref)
+      {:error, reason} ->
+        exit({reason, {__MODULE__, :stop, [stream, acc]}})
+    end
+  end
+
+  # If we reach this branch, the handler was not removed yet,
+  # so we trigger a request for doing so.
+  defp stop(stream, {pid, ref, _} = acc) do
+    _ = GenEvent.remove_handler(pid, {pid, ref}, :shutdown)
+    stop(stream, {:removed, acc})
+  end
+
+  defp wait_for_handler_removal(pid, ref, mon_ref) do
+    receive do
+      {:gen_event_EXIT, {^pid, ^ref}, reason}
+          when reason == :normal
+          when reason == :shutdown
+          when tuple_size(reason) == 3 and elem(reason, 0) == :swapped  ->
+        Process.demonitor(mon_ref, [:flush])
+        :ok
+      {:gen_event_EXIT, {^pid, ^ref}, reason} ->
+        Process.demonitor(mon_ref, [:flush])
+        {:error, reason}
+      {:DOWN, ^mon_ref, _, _, reason} ->
+        {:error, reason}
+    end
+  end
+
+  defp flush_events(ref) do
+    receive do
+      {_from, {_pid, ^ref}, {notify, _event}} when notify in [:notify, :ack_notify, :sync_notify] ->
+        flush_events(ref)
+    after
+      0 -> :ok
+    end
+  end
+end
@@ -11,7 +11,7 @@ defmodule GenServer do
  ## Example

  The GenServer behaviour abstracts the common client-server interaction.
-  Developer are only required to implement the callbacks and functionality they are
+  Developers are only required to implement the callbacks and functionality they are
  interested in.

  Let's start with a code example and then explore the available callbacks.
@@ -349,18 +349,57 @@ defmodule GenServer do
  """
  @spec call(server, term, timeout) :: term
  def call(server, request, timeout \\ 5000) do
-    :gen_server.call(server, request, timeout)
+    try do
+      :gen.call(server, :"$gen_call", request, timeout)
+    catch
+      :exit, reason ->
+        exit({reason, {__MODULE__, :call, [server, request, timeout]}})
+    else
+      {:ok, res} -> res
+    end
  end

  @doc """
  Sends an asynchronous request to the `server`.

-  This function returns `:ok` immediately, regardless of whether the
-  destination node or server does exists. `handle_cast/2` will be called on the
-  server to handle the request.
+  This function returns `:ok` immediately, regardless of
+  whether the destination node or server does exists, unless
+  the server is specified as an atom.
+
+  `handle_cast/2` will be called on the server to handle
+  the request. In case the server is a node which is not
+  yet connected to the caller one, the call is going to
+  block until a connection happens. This is different than
+  the behaviour in OTP's `:gen_server` where the message
+  would be sent by another process, which could cause
+  messages to arrive out of order.
  """
  @spec cast(server, term) :: :ok
-  defdelegate cast(server, request), to: :gen_server
+  def cast(server, request)
+
+  def cast({:global, name}, request) do
+    try do
+      :global.send(name, cast_msg(request))
+      :ok
+    catch
+      _, _ -> :ok
+    end
+  end
+
+  def cast({:via, mod, name}, request) do
+    try do
+      mod.send(name, cast_msg(request))
+      :ok
+    catch
+      _, _ -> :ok
+    end
+  end
+
+  def cast({name, node}, request) when is_atom(name) and is_atom(node),
+    do: do_send({name, node}, cast_msg(request))
+
+  def cast(dest, request) when is_atom(dest) or is_pid(dest),
+    do: do_send(dest, cast_msg(request))

  @doc """
  Casts all servers locally registered as `name` at the specified nodes.
@@ -371,8 +410,19 @@ defmodule GenServer do
  See `multi_call/4` for more information.
  """
  @spec abcast([node], name :: atom, term) :: :abcast
-  def abcast(nodes \\ nodes(), name, request) do
-    :gen_server.abcast(nodes, name, request)
+  def abcast(nodes \\ nodes(), name, request) when is_list(nodes) and is_atom(name) do
+    msg = cast_msg(request)
+    _   = for node <- nodes, do: do_send({name, node}, msg)
+    :abcast
+  end
+
+  defp cast_msg(req) do
+    {:"$gen_cast", req}
+  end
+
+  defp do_send(dest, msg) do
+    send(dest, msg)
+    :ok
  end

  @doc """
@@ -21,7 +21,7 @@ defmodule HashDict do
  @node_size 8
  @node_template :erlang.make_tuple(@node_size, [])

-  @opaque t :: map
+  @opaque t :: %__MODULE__{size: non_neg_integer, root: term}
  @doc false
  defstruct size: 0, root: @node_template

@@ -21,7 +21,7 @@ defmodule HashSet do
  @node_size 8
  @node_template :erlang.make_tuple(@node_size, [])

-  @opaque t :: map
+  @opaque t :: %__MODULE__{size: non_neg_integer, root: term}
  @doc false
  defstruct size: 0, root: @node_template

@@ -212,29 +212,28 @@ defimpl Inspect, for: BitString do

  @doc false
  # Also used by Regex
-  def escape_char(char) when char in ?\000..?\377,
-    do: octify(char)
-
-  def escape_char(char), do: hexify(char)
-
-  defp octify(byte) do
-    << hi :: size(2), mi :: size(3), lo :: size(3) >> = << byte >>
-    << ?\\, ?0 + hi, ?0 + mi, ?0 + lo >>
+  def escape_char(0) do
+    <<?\\, ?0>>
  end

-  defp hexify(char) when char < 0x10000 do
+  def escape_char(char) when char < 0x100 do
+    <<a::4, b::4>> = <<char::size(8)>>
+    <<?\\, ?x, to_hex(a), to_hex(b)>>
+  end
+
+  def escape_char(char) when char < 0x10000 do
    <<a::4, b::4, c::4, d::4>> = <<char::size(16)>>
    <<?\\, ?x, ?{, to_hex(a), to_hex(b), to_hex(c), to_hex(d), ?}>>
  end

-  defp hexify(char) when char < 0x1000000 do
+  def escape_char(char) when char < 0x1000000 do
    <<a::4, b::4, c::4, d::4, e::4, f::4>> = <<char::size(24)>>
    <<?\\, ?x, ?{, to_hex(a), to_hex(b), to_hex(c),
                   to_hex(d), to_hex(e), to_hex(f), ?}>>
  end

  defp to_hex(c) when c in 0..9, do: ?0+c
-  defp to_hex(c) when c in 10..15, do: ?a+c-10
+  defp to_hex(c) when c in 10..15, do: ?A+c-10

  defp append(<<h, t :: binary>>, binary), do: append(t, << binary :: binary, h >>)
  defp append(<<>>, binary), do: binary
@@ -272,25 +271,6 @@ defimpl Inspect, for: BitString do
 end

 defimpl Inspect, for: List do
-  @doc ~S"""
-  Represents a list, checking if it can be printed or not.
-  If so, a single-quoted representation is returned,
-  otherwise the brackets syntax is used. Keywords are
-  printed in keywords syntax.
-
-  ## Examples
-
-      iex> inspect('bar')
-      "'bar'"
-
-      iex> inspect([0|'bar'])
-      "[0, 98, 97, 114]"
-
-      iex> inspect([:foo,:bar])
-      "[:foo, :bar]"
-
-  """
-
  def inspect([], _opts), do: "[]"

  def inspect(thing, %Inspect.Opts{char_lists: lists} = opts) do
@@ -298,9 +278,9 @@ defimpl Inspect, for: List do
      lists == :as_char_lists or (lists == :infer and printable?(thing)) ->
        << ?', Inspect.BitString.escape(IO.chardata_to_string(thing), ?') :: binary, ?' >>
      keyword?(thing) ->
-        surround_many("[", thing, "]", opts.limit, &keyword(&1, opts))
+        surround_many("[", thing, "]", opts, &keyword/2)
      true ->
-        surround_many("[", thing, "]", opts.limit, &to_doc(&1, opts))
+        surround_many("[", thing, "]", opts, &to_doc/2)
    end
  end

@@ -347,7 +327,7 @@ defimpl Inspect, for: Tuple do
  def inspect({}, _opts), do: "{}"

  def inspect(tuple, opts) do
-    surround_many("{", Tuple.to_list(tuple), "}", opts.limit, &to_doc(&1, opts))
+    surround_many("{", Tuple.to_list(tuple), "}", opts, &to_doc/2)
  end
 end

@@ -358,14 +338,14 @@ defimpl Inspect, for: Map do

  def inspect(map, name, opts) do
    map = :maps.to_list(map)
-    surround_many("%" <> name <> "{", map, "}", opts.limit, traverse_fun(map, opts))
+    surround_many("%" <> name <> "{", map, "}", opts, traverse_fun(map))
  end

-  defp traverse_fun(list, opts) do
+  defp traverse_fun(list) do
    if Inspect.List.keyword?(list) do
-      &Inspect.List.keyword(&1, opts)
+      &Inspect.List.keyword/2
    else
-      &to_map(&1, opts)
+      &to_map/2
    end
  end

@@ -378,8 +358,28 @@ defimpl Inspect, for: Map do
 end

 defimpl Inspect, for: Integer do
-  def inspect(thing, _opts) do
-    Integer.to_string(thing)
+  def inspect(thing, %Inspect.Opts{base: base}) do
+    Integer.to_string(thing, base_to_value(base))
+    |> prepend_prefix(base)
+  end
+
+  defp base_to_value(base) do
+    case base do
+      :binary  -> 2
+      :decimal -> 10
+      :octal   -> 8
+      :hex     -> 16
+    end
+  end
+
+  defp prepend_prefix(value, :decimal), do: value
+  defp prepend_prefix(value, base) do
+    prefix = case base do
+      :binary -> "0b"
+      :octal  -> "0o"
+      :hex    -> "0x"
+    end
+    prefix <> value
  end
 end

@@ -29,15 +29,30 @@ defmodule Inspect.Opts do

    * `:pretty` - if set to true enables pretty printing, defaults to false.

-    * `:width` - defaults to the 80 characters.
+    * `:width` - defaults to the 80 characters, used when pretty is true or
+      when printing to IO devices.
+
+    * `:base` - print integers as :binary, :octal, :decimal, or :hex, defaults
+      to :decimal
+
  """

-  defstruct structs: true :: boolean,
-            binaries: :infer :: :infer | :as_binaries | :as_strings,
-            char_lists: :infer :: :infer | :as_lists | :as_char_lists,
-            limit: 50 :: pos_integer,
-            width: 80 :: pos_integer | :infinity,
-            pretty: false :: boolean
+  defstruct structs: true,
+            binaries: :infer,
+            char_lists: :infer,
+            limit: 50,
+            width: 80,
+            base: :decimal,
+            pretty: false
+
+  @type t :: %__MODULE__{
+               structs: boolean,
+               binaries: :infer | :as_binaries | :as_strings,
+               char_lists: :infer | :as_lists | :as_char_lists,
+               limit: pos_integer,
+               width: pos_integer | :infinity,
+               base: :decimal | :binary | :hex | :octal,
+               pretty: boolean}
 end

 defmodule Inspect.Algebra do
@@ -58,8 +73,8 @@ defmodule Inspect.Algebra do
  elements together and render them:

      iex> doc = Inspect.Algebra.concat(Inspect.Algebra.empty, "foo")
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "foo"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["foo"]

  The functions `nest/2`, `space/2` and `line/2` help you put the
  document together into a rigid structure. However, the document
@@ -69,15 +84,15 @@ defmodule Inspect.Algebra do
  render it:

      iex> doc = Inspect.Algebra.glue("a", " ", "b")
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "a b"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["a", " ", "b"]

  Notice the break was represented as is, because we haven't reached
  a line limit. Once we do, it is replaced by a newline:

      iex> doc = Inspect.Algebra.glue(String.duplicate("a", 20), " ", "b")
-      iex> Inspect.Algebra.pretty(doc, 10)
-      "aaaaaaaaaaaaaaaaaaaa\nb"
+      iex> Inspect.Algebra.format(doc, 10)
+      ["aaaaaaaaaaaaaaaaaaaa", "\n", "b"]

  Finally, this module also contains Elixir related functions, a bit
  tied to Elixir formatting, namely `surround/3` and `surround_many/5`.
@@ -170,10 +185,29 @@ defmodule Inspect.Algebra do
        Inspect.inspect(map, opts)
      rescue
        e ->
+          stacktrace = System.stacktrace
+
+          # Because we try to raise a nice error message in case
+          # we can't inspect a struct, there is a chance the error
+          # message itself relies on the struct being printed, so
+          # we need to trap the inspected messages to guarantee
+          # we won't try to render any failed instruct when building
+          # the error message.
+          if Process.get(:inspect_trap) do
+            Inspect.Map.inspect(map, opts)
+          else
+            try do
+              Process.put(:inspect_trap, true)
              res = Inspect.Map.inspect(map, opts)
-          raise ArgumentError,
+              formatted = IO.iodata_to_binary(format(res, :infinity))
+              reraise ArgumentError,
                "Got #{inspect e.__struct__} with message " <>
-            "\"#{Exception.message(e)}\" while inspecting #{pretty(res, opts.width)}"
+                "\"#{Exception.message(e)}\" while inspecting #{formatted}",
+                stacktrace
+            after
+              Process.delete(:inspect_trap)
+            end
+          end
      end
    else
      Inspect.Map.inspect(map, opts)
@@ -201,9 +235,9 @@ defmodule Inspect.Algebra do

  ## Examples

-      iex> doc = Inspect.Algebra.concat "Tasteless", "Artosis"
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "TastelessArtosis"
+      iex> doc = Inspect.Algebra.concat "hello", "world"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["hello", "world"]

  """
  @spec concat(t, t) :: doc_cons
@@ -227,8 +261,8 @@ defmodule Inspect.Algebra do
  ## Examples

      iex> doc = Inspect.Algebra.nest(Inspect.Algebra.glue("hello", "world"), 5)
-      iex> Inspect.Algebra.pretty(doc, 5)
-      "hello\n     world"
+      iex> Inspect.Algebra.format(doc, 5)
+      ["hello", "\n     ", "world"]

  """
  @spec nest(t, non_neg_integer) :: doc_nest
@@ -252,15 +286,15 @@ defmodule Inspect.Algebra do
  Let's glue two docs together with a break and then render it:

      iex> doc = Inspect.Algebra.glue("a", " ", "b")
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "a b"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["a", " ", "b"]

  Notice the break was represented as is, because we haven't reached
  a line limit. Once we do, it is replaced by a newline:

      iex> doc = Inspect.Algebra.glue(String.duplicate("a", 20), " ", "b")
-      iex> Inspect.Algebra.pretty(doc, 10)
-      "aaaaaaaaaaaaaaaaaaaa\nb"
+      iex> Inspect.Algebra.format(doc, 10)
+      ["aaaaaaaaaaaaaaaaaaaa", "\n", "b"]

  """
  @spec break(binary) :: doc_break
@@ -303,10 +337,10 @@ defmodule Inspect.Algebra do
      ...>       "B"
      ...>     )
      ...> ))
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "Hello, A B"
-      iex> Inspect.Algebra.pretty(doc, 6)
-      "Hello,\nA B"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["Hello,", " ", "A", " ", "B"]
+      iex> Inspect.Algebra.format(doc, 6)
+      ["Hello,", "\n", "A", " ", "B"]

  """
  @spec group(t) :: doc_group
@@ -320,8 +354,8 @@ defmodule Inspect.Algebra do
  ## Examples

      iex> doc = Inspect.Algebra.space "Hughes", "Wadler"
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "Hughes Wadler"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["Hughes", " ", "Wadler"]

  """
  @spec space(t, t) :: doc_cons
@@ -333,8 +367,8 @@ defmodule Inspect.Algebra do
  ## Examples

      iex> doc = Inspect.Algebra.line "Hughes", "Wadler"
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "Hughes\nWadler"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["Hughes", "\n", "Wadler"]

  """
  @spec line(t, t) :: doc_cons
@@ -350,8 +384,8 @@ defmodule Inspect.Algebra do
      iex> doc = Inspect.Algebra.folddoc(doc, fn(x,y) ->
      ...>   Inspect.Algebra.concat [x, "!", y]
      ...> end)
-      iex> Inspect.Algebra.pretty(doc, 80)
-      "A!B"
+      iex> Inspect.Algebra.format(doc, 80)
+      ["A", "!", "B"]

  """
  @spec folddoc([t], ((t, t) -> t)) :: t
@@ -371,8 +405,8 @@ defmodule Inspect.Algebra do
  ## Examples

      iex> doc = Inspect.Algebra.surround "[", Inspect.Algebra.glue("a", "b"), "]"
-      iex> Inspect.Algebra.pretty(doc, 3)
-      "[a\n b]"
+      iex> Inspect.Algebra.format(doc, 3)
+      ["[", "a", "\n ", "b", "]"]

  """
  @spec surround(binary, t, binary) :: t
@@ -381,55 +415,63 @@ defmodule Inspect.Algebra do
  end

  @doc ~S"""
-  Maps and glues a collection of items together using the given separator
-  and surrounds them. A limit can be passed which, once reached, stops
-  gluing and outputs "..." instead.
+  Maps and glues a collection of items.
+
+  It uses the given left and right as surrounding and a separator for
+  each item. A limit can be passed which, once reached, stops gluing
+  and outputs "..." instead.

  ## Examples

-      iex> doc = Inspect.Algebra.surround_many("[", Enum.to_list(1..5), "]", :infinity, &Integer.to_string(&1))
-      iex> Inspect.Algebra.pretty(doc, 5)
+      iex> doc = Inspect.Algebra.surround_many("[", Enum.to_list(1..5), "]",
+      ...>         %Inspect.Opts{limit: :infinity}, fn i, _opts -> to_string(i) end)
+      iex> Inspect.Algebra.format(doc, 5) |> IO.iodata_to_binary
      "[1,\n 2,\n 3,\n 4,\n 5]"

-      iex> doc = Inspect.Algebra.surround_many("[", Enum.to_list(1..5), "]", 3, &Integer.to_string(&1))
-      iex> Inspect.Algebra.pretty(doc, 20)
+      iex> doc = Inspect.Algebra.surround_many("[", Enum.to_list(1..5), "]",
+      ...>         %Inspect.Opts{limit: 3}, fn i, _opts -> to_string(i) end)
+      iex> Inspect.Algebra.format(doc, 20) |> IO.iodata_to_binary
      "[1, 2, 3, ...]"

-      iex> doc = Inspect.Algebra.surround_many("[", Enum.to_list(1..5), "]", 3, &Integer.to_string(&1), "!")
-      iex> Inspect.Algebra.pretty(doc, 20)
+      iex> doc = Inspect.Algebra.surround_many("[", Enum.to_list(1..5), "]",
+      ...>         %Inspect.Opts{limit: 3}, fn i, _opts -> to_string(i) end, "!")
+      iex> Inspect.Algebra.format(doc, 20) |> IO.iodata_to_binary
      "[1! 2! 3! ...]"
-
  """
-  @spec surround_many(binary, [any], binary, integer | :infinity, (term -> t), binary) :: t
-  def surround_many(left, docs, right, limit, fun, separator \\ @surround_separator)
+  @spec surround_many(binary, [any], binary, Inspect.Opts.t, (term, Inspect.Opts.t -> t), binary) :: t
+  def surround_many(left, docs, right, opts, fun, separator \\ @surround_separator) do
+    do_surround_many(left, docs, right, opts.limit, opts, fun, separator)
+  end

-  def surround_many(left, [], right, _, _fun, _) do
+  defp do_surround_many(left, [], right, _, _opts, _fun, _) do
    concat(left, right)
  end

-  def surround_many(left, docs, right, limit, fun, sep) do
-    surround(left, surround_many(docs, limit, fun, sep), right)
+  defp do_surround_many(left, docs, right, limit, _opts, fun, sep) do
+    surround(left, do_surround_many(docs, limit, _opts, fun, sep), right)
  end

-  defp surround_many(_, 0, _fun, _sep) do
+  defp do_surround_many(_, 0, _opts, _fun, _sep) do
    "..."
  end

-  defp surround_many([h], _limit, fun, _sep) do
-    fun.(h)
+  defp do_surround_many([h], limit, opts, fun, _sep) do
+    fun.(h, %{opts | limit: limit})
  end

-  defp surround_many([h|t], limit, fun, sep) when is_list(t) do
+  defp do_surround_many([h|t], limit, opts, fun, sep) when is_list(t) do
+    limit = decrement(limit)
    glue(
-      concat(fun.(h), sep),
-      surround_many(t, decrement(limit), fun, sep)
+      concat(fun.(h, %{opts | limit: limit}), sep),
+      do_surround_many(t, limit, opts, fun, sep)
    )
  end

-  defp surround_many([h|t], _limit, fun, _sep) do
+  defp do_surround_many([h|t], limit, opts, fun, _sep) do
+    limit = decrement(limit)
    glue(
-      concat(fun.(h), @tail_separator),
-      fun.(t)
+      concat(fun.(h, %{opts | limit: limit}), @tail_separator),
+      fun.(t, %{opts | limit: limit})
    )
  end

@@ -437,50 +479,45 @@ defmodule Inspect.Algebra do
  defp decrement(counter),   do: counter - 1

  @doc """
-  The pretty printing function.
+  The formatting function.

  Takes the maximum width and a document to print as its arguments
-  and returns the string representation of the best layout for the
+  and returns an IO data representation of the best layout for the
  document to fit in the given width.
  """
-  @spec pretty(t, non_neg_integer | :infinity) :: binary
-  def pretty(d, w) do
-    sdoc = format w, 0, [{0, default_mode(w), doc_group(d)}]
-    render(sdoc)
+  @spec format(t, non_neg_integer | :infinity) :: iodata
+  def format(d, w) do
+    format(w, 0, [{0, default_mode(w), doc_group(d)}])
  end

  defp default_mode(:infinity), do: :flat
  defp default_mode(_),         do: :break

-  # Rendering and internal helpers
-
  # Record representing the document mode to be rendered: flat or broken
  @typep mode :: :flat | :break

-  @doc false
  @spec fits?(integer, [{integer, mode, t}]) :: boolean
-  def fits?(w, _) when w < 0,                      do: false
-  def fits?(_, []),                                do: true
-  def fits?(_, [{_, _, :doc_line} | _]),           do: true
-  def fits?(w, [{_, _, :doc_nil} | t]),            do: fits?(w, t)
-  def fits?(w, [{i, m, doc_cons(x, y)} | t]),      do: fits?(w, [{i, m, x} | [{i, m, y} | t]])
-  def fits?(w, [{i, m, doc_nest(x, j)} | t]),      do: fits?(w, [{i + j, m, x} | t])
-  def fits?(w, [{i, _, doc_group(x)} | t]),        do: fits?(w, [{i, :flat, x} | t])
-  def fits?(w, [{_, _, s} | t]) when is_binary(s), do: fits?((w - byte_size s), t)
-  def fits?(w, [{_, :flat, doc_break(s)} | t]),    do: fits?((w - byte_size s), t)
-  def fits?(_, [{_, :break, doc_break(_)} | _]),   do: true
+  defp fits?(w, _) when w < 0,                      do: false
+  defp fits?(_, []),                                do: true
+  defp fits?(_, [{_, _, :doc_line} | _]),           do: true
+  defp fits?(w, [{_, _, :doc_nil} | t]),            do: fits?(w, t)
+  defp fits?(w, [{i, m, doc_cons(x, y)} | t]),      do: fits?(w, [{i, m, x} | [{i, m, y} | t]])
+  defp fits?(w, [{i, m, doc_nest(x, j)} | t]),      do: fits?(w, [{i + j, m, x} | t])
+  defp fits?(w, [{i, _, doc_group(x)} | t]),        do: fits?(w, [{i, :flat, x} | t])
+  defp fits?(w, [{_, _, s} | t]) when is_binary(s), do: fits?((w - byte_size s), t)
+  defp fits?(w, [{_, :flat, doc_break(s)} | t]),    do: fits?((w - byte_size s), t)
+  defp fits?(_, [{_, :break, doc_break(_)} | _]),   do: true

-  @doc false
  @spec format(integer | :infinity, integer, [{integer, mode, t}]) :: [binary]
-  def format(_, _, []),                                do: []
-  def format(w, _, [{i, _, :doc_line} | t]),           do: [indent(i) | format(w, i, t)]
-  def format(w, k, [{_, _, :doc_nil} | t]),            do: format(w, k, t)
-  def format(w, k, [{i, m, doc_cons(x, y)} | t]),      do: format(w, k, [{i, m, x} | [{i, m, y} | t]])
-  def format(w, k, [{i, m, doc_nest(x, j)} | t]),      do: format(w, k, [{i + j, m, x} | t])
-  def format(w, k, [{i, m, doc_group(x)} | t]),        do: format(w, k, [{i, m, x} | t])
-  def format(w, k, [{_, _, s} | t]) when is_binary(s), do: [s | format(w, (k + byte_size s), t)]
-  def format(w, k, [{_, :flat, doc_break(s)} | t]),    do: [s | format(w, (k + byte_size s), t)]
-  def format(w, k, [{i, :break, doc_break(s)} | t]) do
+  defp format(_, _, []),                                do: []
+  defp format(w, _, [{i, _, :doc_line} | t]),           do: [indent(i) | format(w, i, t)]
+  defp format(w, k, [{_, _, :doc_nil} | t]),            do: format(w, k, t)
+  defp format(w, k, [{i, m, doc_cons(x, y)} | t]),      do: format(w, k, [{i, m, x} | [{i, m, y} | t]])
+  defp format(w, k, [{i, m, doc_nest(x, j)} | t]),      do: format(w, k, [{i + j, m, x} | t])
+  defp format(w, k, [{i, m, doc_group(x)} | t]),        do: format(w, k, [{i, m, x} | t])
+  defp format(w, k, [{_, _, s} | t]) when is_binary(s), do: [s | format(w, (k + byte_size s), t)]
+  defp format(w, k, [{_, :flat, doc_break(s)} | t]),    do: [s | format(w, (k + byte_size s), t)]
+  defp format(w, k, [{i, :break, doc_break(s)} | t]) do
    k = k + byte_size(s)

    if w == :infinity or fits?(w - k, t) do
@@ -492,10 +529,4 @@ defmodule Inspect.Algebra do

  defp indent(0), do: @newline
  defp indent(i), do: @newline <> :binary.copy(" ", i)
-
-  @doc false
-  @spec render([binary]) :: binary
-  def render(sdoc) do
-    IO.iodata_to_binary sdoc
-  end
 end
@@ -9,9 +9,10 @@ defmodule Integer do
  Determines if an integer is odd.

  Returns `true` if `n` is an odd number, otherwise `false`.
-  Implemented as a macro so it is allowed in guard clauses.
+
+  Allowed in guard clauses.
  """
-  defmacro odd?(n) do
+  defmacro is_odd(n) do
    quote do: (unquote(n) &&& 1) == 1
  end

@@ -19,9 +20,10 @@ defmodule Integer do
  Determines if an integer is even.

  Returns `true` if `n` is an even number, otherwise `false`.
-  Implemented as a macro so it is allowed in guard clauses.
+
+  Allowed in guard clauses.
  """
-  defmacro even?(n) do
+  defmacro is_even(n) do
    quote do: (unquote(n) &&& 1) == 0
  end

@@ -99,7 +101,7 @@ defmodule Integer do
      "64"

  """
-  @spec to_string(integer, pos_integer) :: String.t
+  @spec to_string(integer, 2..36) :: String.t
  def to_string(some_integer, base) do
    :erlang.integer_to_binary(some_integer, base)
  end
@@ -115,7 +117,7 @@ defmodule Integer do
      '7'

  """
-  @spec to_char_list(integer) :: list
+  @spec to_char_list(integer) :: char_list
  def to_char_list(number) do
    :erlang.integer_to_list(number)
  end
@@ -132,7 +134,7 @@ defmodule Integer do
      '3FF'

  """
-  @spec to_char_list(integer, pos_integer) :: list
+  @spec to_char_list(integer, 2..36) :: char_list
  def to_char_list(number, base) do
    :erlang.integer_to_list(number, base)
  end
@@ -43,8 +43,10 @@ defmodule IO do
  end

  @doc """
-  Reads `count` characters from the IO device or until
-  the end of the line if `:line` is given. It returns:
+  Reads `count` characters from the IO device, a whole
+  `:line` or the whole device with `:all`.
+
+  It returns:

    * `data` - the input characters

@@ -53,10 +55,17 @@ defmodule IO do
    * `{:error, reason}` - other (rare) error condition;
      for instance, `{:error, :estale}` if reading from an
      NFS volume
+
+  If `:all` is given, `:eof` is never returned, but an
+  empty string in case the device has reached EOF.
  """
-  @spec read(device, :line | non_neg_integer) :: chardata | nodata
+  @spec read(device, :all | :line | non_neg_integer) :: chardata | nodata
  def read(device \\ group_leader, chars_or_line)

+  def read(device, :all) do
+    do_read_all(map_dev(device), "")
+  end
+
  def read(device, :line) do
    :io.get_line(map_dev(device), '')
  end
@@ -65,9 +74,19 @@ defmodule IO do
    :io.get_chars(map_dev(device), '', count)
  end

+  defp do_read_all(mapped_dev, acc) do
+    case :io.get_line(mapped_dev, "") do
+      line when is_binary(line) -> do_read_all(mapped_dev, acc <> line)
+      :eof -> acc
+      other -> other
+    end
+  end
+
  @doc """
-  Reads `count` bytes from the IO device or until
-  the end of the line if `:line` is given. It returns:
+  Reads `count` characters from the IO device, a whole
+  `:line` or the whole device with `:all`.
+
+  It returns:

    * `data` - the input characters

@@ -76,10 +95,20 @@ defmodule IO do
    * `{:error, reason}` - other (rare) error condition;
      for instance, `{:error, :estale}` if reading from an
      NFS volume
+
+  If `:all` is given, `:eof` is never returned, but an
+  empty string in case the device has reached EOF.
+
+  Note: do not use this function on IO devices in unicode mode
+  as it will return the wrong result.
  """
-  @spec binread(device, :line | non_neg_integer) :: iodata | nodata
+  @spec binread(device, :all | :line | non_neg_integer) :: iodata | nodata
  def binread(device \\ group_leader, chars_or_line)

+  def binread(device, :all) do
+    do_binread_all(map_dev(device), "")
+  end
+
  def binread(device, :line) do
    case :file.read_line(map_dev(device)) do
      {:ok, data} -> data
@@ -94,6 +123,15 @@ defmodule IO do
    end
  end

+  @read_all_size 4096
+  defp do_binread_all(mapped_dev, acc) do
+    case :file.read(mapped_dev, @read_all_size) do
+      {:ok, data} -> do_binread_all(mapped_dev, acc <> data)
+      :eof -> acc
+      other -> other
+    end
+  end
+
  @doc """
  Writes the given argument to the given device.

@@ -119,6 +157,9 @@ defmodule IO do
  as a binary, no unicode conversion happens.

  Check `write/2` for more information.
+
+  Note: do not use this function on IO devices in unicode mode
+  as it will return the wrong result.
  """
  @spec binwrite(device, iodata) :: :ok | {:error, term}
  def binwrite(device \\ group_leader(), item) when is_iodata(item) do
@@ -139,17 +180,13 @@ defmodule IO do
  @doc """
  Inspects and writes the given argument to the device.

-  It sets by default pretty printing to true and returns
-  the item itself.
-
-  Note this function does not use the IO device width
-  because some IO devices does not implement the
-  appropriate functions. Setting the width must be done
-  explicitly by passing the `:width` option.
+  It enables pretty printing by default with width of
+  80 characters. The width can be changed by explicitly
+  passing the `:width` option.

  ## Examples

-      IO.inspect Process.list
+      IO.inspect Process.list, width: 40

  """
  @spec inspect(term, Keyword.t) :: term
@@ -162,8 +199,9 @@ defmodule IO do
  """
  @spec inspect(device, term, Keyword.t) :: term
  def inspect(device, item, opts) when is_list(opts) do
-    opts = Keyword.put_new(opts, :pretty, true)
-    puts device, Kernel.inspect(item, opts)
+    opts   = struct(Inspect.Opts, opts)
+    iodata = Inspect.Algebra.format(Inspect.Algebra.to_doc(item, opts), opts.width)
+    puts device, iodata
    item
  end

@@ -263,6 +301,9 @@ defmodule IO do

  Note that an IO stream has side effects and every time
  you go over the stream you may get different results.
+
+  Finally, do not use this function on IO devices in unicode
+  mode as it will return the wrong result.
  """
  @spec binstream(device, :line | pos_integer) :: Enumerable.t
  def binstream(device, line_or_bytes) do
@@ -354,11 +395,11 @@ defmodule IO do
  def each_stream(device, what) do
    case read(device, what) do
      :eof ->
-        nil
+        {:halt, device}
      {:error, reason} ->
        raise IO.StreamError, reason: reason
      data ->
-        {data, device}
+        {[data], device}
    end
  end

@@ -366,11 +407,11 @@ defmodule IO do
  def each_binstream(device, what) do
    case binread(device, what) do
      :eof ->
-        nil
+        {:halt, device}
      {:error, reason} ->
        raise IO.StreamError, reason: reason
      data ->
-        {data, device}
+        {[data], device}
    end
  end

@@ -7,7 +7,7 @@ defmodule IO.ANSI.Sequence do
        "\e[#{unquote(code)}#{unquote(terminator)}"
      end

-      defp escape_sequence(unquote(Atom.to_char_list(name))) do
+      defp format_sequence(unquote(name)) do
        unquote(name)()
      end
    end
@@ -24,19 +24,21 @@ defmodule IO.ANSI do

  import IO.ANSI.Sequence

-  @doc """
-  Checks whether the default I/O device is a terminal or a file.
+  @typep ansicode :: atom()
+  @typep ansilist :: maybe_improper_list(char() | ansicode() | binary() | ansilist(), binary() | ansicode() | [])
+  @type  ansidata :: ansilist() | ansicode() | binary()

-  Used to identify whether printing ANSI escape sequences will likely
-  be displayed as intended. This is checked by sending a message to
-  the group leader. In case the group leader does not support the message,
-  it will likely lead to a timeout (and a slow down on execution time).
+  @doc """
+  Checks if ANSI coloring is supported and enabled on this machine.
+
+  This function simply reads the configuration value for
+  `:ansi_enabled` in the `:elixir` application. The value is by
+  default false unless Elixir can detect during startup that
+  both `stdout` and `stderr` are terminals.
  """
-  @spec terminal? :: boolean
-  @spec terminal?(:io.device) :: boolean
-  def terminal?(device \\ :erlang.group_leader) do
-    !match?({:win32, _}, :os.type()) and
-      match?({:ok, _}, :io.columns(device))
+  @spec enabled? :: boolean
+  def enabled? do
+    Application.get_env(:elixir, :ansi_enabled, false)
  end

  @doc "Resets all attributes"
@@ -130,99 +132,78 @@ defmodule IO.ANSI do
  @doc "Clear screen"
  defsequence :clear, "2", "J"

-  defp escape_sequence(other) do
+  defp format_sequence(other) do
    raise ArgumentError, "invalid ANSI sequence specification: #{other}"
  end

  @doc ~S"""
-  Escapes a string by converting named ANSI sequences into actual ANSI codes.
+  Formats a chardata-like argument by converting named ANSI sequences into actual
+  ANSI codes.

-  The format for referring to sequences is `%{red}` and `%{red,bright}` (for
-  multiple sequences).
+  The named sequences are represented by atoms.

-  It will also append a `%{reset}` to the string. If you don't want this
-  behaviour, use `escape_fragment/2`.
+  It will also append an `IO.ANSI.reset` to the chardata when a conversion is
+  performed. If you don't want this behaviour, use `format_fragment/2`.

  An optional boolean parameter can be passed to enable or disable
  emitting actual ANSI codes. When `false`, no ANSI codes will emitted.
-  By default, standard output will be checked if it is a terminal capable
-  of handling these sequences (using `terminal?/1` function)
+  By default checks if ANSI is enabled using the `enabled?/0` function.

  ## Examples

-      iex> IO.ANSI.escape("Hello %{red,bright,green}yes", true)
-      "Hello \e[31m\e[1m\e[32myes\e[0m"
+      iex> IO.ANSI.format(["Hello, ", :red, :bright, "world!"], true)
+      [[[[[[], "Hello, "] | "\e[31m"] | "\e[1m"], "world!"] | "\e[0m"]

  """
-  @spec escape(String.t, emit :: boolean) :: String.t
-  def escape(string, emit \\ terminal?) when is_binary(string) and is_boolean(emit) do
-    {rendered, emitted} = do_escape(string, emit, false, nil, [])
-    if emitted do
-      rendered <> reset
-    else
-      rendered
-    end
+  def format(chardata, emit \\ enabled?) when is_boolean(emit) do
+    do_format(chardata, [], [], emit, :maybe)
  end

  @doc ~S"""
-  Escapes a string by converting named ANSI sequences into actual ANSI codes.
+  Formats a chardata-like argument by converting named ANSI sequences into actual
+  ANSI codes.

-  The format for referring to sequences is `%{red}` and `%{red,bright}` (for
-  multiple sequences).
+  The named sequences are represented by atoms.

  An optional boolean parameter can be passed to enable or disable
  emitting actual ANSI codes. When `false`, no ANSI codes will emitted.
-  By default, standard output will be checked if it is a terminal capable
-  of handling these sequences (using `terminal?/1` function)
+  By default checks if ANSI is enabled using the `enabled?/0` function.

  ## Examples

-      iex> IO.ANSI.escape_fragment("Hello %{red,bright,green}yes", true)
-      "Hello \e[31m\e[1m\e[32myes"
-
-      iex> IO.ANSI.escape_fragment("%{reset}bye", true)
-      "\e[0mbye"
+      iex> IO.ANSI.format_fragment([:bright, 'Word'], true)
+      [[[[[[] | "\e[1m"], 87], 111], 114], 100]

  """
-  @spec escape_fragment(String.t, emit :: boolean) :: String.t
-  def escape_fragment(string, emit \\ terminal?) when is_binary(string) and is_boolean(emit) do
-    {escaped, _emitted} = do_escape(string, emit, false, nil, [])
-    escaped
+  def format_fragment(chardata, emit \\ enabled?) when is_boolean(emit) do
+    do_format(chardata, [], [], emit, false)
  end

-  defp do_escape(<<?}, t :: binary>>, emit, emitted, buffer, acc) when is_list(buffer) do
-    sequences =
-      buffer
-      |> Enum.reverse()
-      |> :string.tokens(',')
-      |> Enum.map(&(&1 |> :string.strip |> escape_sequence))
-      |> Enum.reverse()
-
-    if emit and sequences != [] do
-      do_escape(t, emit, true, nil, sequences ++ acc)
-    else
-      do_escape(t, emit, emitted, nil, acc)
-    end
+  defp do_format([term | rest], rem, acc, emit, append_reset) do
+    do_format(term, [rest | rem], acc, emit, append_reset)
  end

-  defp do_escape(<<h, t :: binary>>, emit, emitted, buffer, acc) when is_list(buffer) do
-    do_escape(t, emit, emitted, [h|buffer], acc)
+  defp do_format(term, rem, acc, true, append_reset) when is_atom(term) do
+    do_format([], rem, [acc | format_sequence(term)], true, !!append_reset)
  end

-  defp do_escape(<<>>, _emit, _emitted, buffer, _acc) when is_list(buffer) do
-    buffer = IO.iodata_to_binary Enum.reverse(buffer)
-    raise ArgumentError, "missing } for escape fragment #{buffer}"
+  defp do_format(term, rem, acc, false, append_reset) when is_atom(term) do
+    do_format([], rem, acc, false, append_reset)
  end

-  defp do_escape(<<?%, ?{, t :: binary>>, emit, emitted, nil, acc) do
-    do_escape(t, emit, emitted, [], acc)
+  defp do_format(term, rem, acc, emit, append_reset) when not is_list(term) do
+    do_format([], rem, [acc | [term]], emit, append_reset)
  end

-  defp do_escape(<<h, t :: binary>>, emit, emitted, nil, acc) do
-    do_escape(t, emit, emitted, nil, [h|acc])
+  defp do_format([], [next | rest], acc, emit, append_reset) do
+    do_format(next, rest, acc, emit, append_reset)
  end

-  defp do_escape(<<>>, _emit, emitted, nil, acc) do
-    {IO.iodata_to_binary(Enum.reverse(acc)), emitted}
+  defp do_format([], [], acc, true, true) do
+    [acc | IO.ANSI.reset]
+  end
+
+  defp do_format([], [], acc, _emit, _append_reset) do
+    acc
  end
 end
@@ -9,11 +9,12 @@ defmodule IO.ANSI.Docs do
  The supported values are:

    * `:enabled`           - toggles coloring on and off (true)
-    * `:doc_code`        - code blocks (cyan, bright)
-    * `:doc_inline_code` - inline code (cyan)
-    * `:doc_headings`    - h1 and h2 headings (yellow, bright)
-    * `:doc_title`       - top level heading (reverse, yellow, bright)
    * `:doc_bold`          - bold text (bright)
+    * `:doc_code`          - code blocks (cyan, bright)
+    * `:doc_headings`      - h1 and h2 headings (yellow, bright)
+    * `:doc_inline_code`   - inline code (cyan)
+    * `:doc_table_heading` - style for table headings
+    * `:doc_title`         - top level heading (reverse, yellow, bright)
    * `:doc_underline`     - underlined text (underline)
    * `:width`             - the width to format the text (80)

@@ -22,12 +23,13 @@ defmodule IO.ANSI.Docs do
  """
  def default_options do
    [enabled:           true,
-     doc_code: "cyan,bright",
-     doc_inline_code: "cyan",
-     doc_headings: "yellow,bright",
-     doc_title: "reverse,yellow,bright",
-     doc_bold: "bright",
-     doc_underline: "underline",
+     doc_bold:          [:bright],
+     doc_code:          [:cyan, :bright],
+     doc_headings:      [:yellow],
+     doc_inline_code:   [:cyan],
+     doc_table_heading: [:reverse],
+     doc_title:         [:reverse, :yellow],
+     doc_underline:     [:underline],
     width:             80]
  end

@@ -43,12 +45,13 @@ defmodule IO.ANSI.Docs do
    padding = div(width + String.length(heading), 2)
    heading = heading |> String.rjust(padding) |> String.ljust(width)
    write(:doc_title, heading, options)
+    newline_after_block
  end

  @doc """
  Prints the documentation body.

-  In addition to the priting string, takes a set of options
+  In addition to the printing string, takes a set of options
  defined in `default_options/1`.
  """
  def print(doc, options \\ []) do
@@ -56,50 +59,61 @@ defmodule IO.ANSI.Docs do
    doc
    |> String.split(["\r\n","\n"], trim: false)
    |> Enum.map(&String.rstrip/1)
-    |> process("", options)
+    |> process([], "", options)
  end

-  defp process([], _indent, _options), do: nil
+  defp process([], text, indent, options) do
+    write_text(text, indent, options)
+  end

-  defp process(["# " <> heading | rest], _indent, options) do
+  defp process(["# " <> heading | rest], text, indent, options) do
+    write_text(text, indent, options)
    write_h1(String.strip(heading), options)
-    process(rest, "", options)
+    process(rest, [], "", options)
  end

-  defp process(["## " <> heading | rest], _indent, options) do
+  defp process(["## " <> heading | rest], text, indent, options) do
+    write_text(text, indent, options)
    write_h2(String.strip(heading), options)
-    process(rest, "", options)
+    process(rest, [], "", options)
  end

-  defp process(["### " <> heading | rest], indent, options) do
+  defp process(["### " <> heading | rest], text, indent, options) do
+    write_text(text, indent, options)
    write_h3(String.strip(heading), indent, options)
-    process(rest, indent, options)
+    process(rest, [], "", options)
  end

-  defp process(["" | rest], indent, options) do
-    process(rest, indent, options)
+  defp process(["" | rest], text, indent, options) do
+    write_text(text, indent, options)
+    process(rest, [], indent, options)
  end

-  defp process(["    " <> line | rest], indent, options) do
+  defp process(["    " <> line | rest], text, indent, options) do
+    write_text(text, indent, options)
    process_code(rest, [line], indent, options)
  end

-  defp process([line | rest], indent, options) do
-    {stripped, count} = strip_spaces(line, 0)
+  defp process(all=[line | rest], text, indent, options) do
+    {stripped, count} = strip_spaces(line, 0, :infinity)
+    if is_table_line?(stripped) and rest != [] and is_table_line?(hd(rest)) do
+      write_text(text, indent, options)
+      process_table(all, indent, options)
+    else
      case stripped do
        <<bullet, ?\s, item :: binary>> when bullet in @bullets ->
-        process_list(item, rest, count, indent, options)
+          write_text(text, indent, options)
+          process_list("• ", item, rest, count, indent, options)
+        <<d1, ?., ?\s, item :: binary>> when d1 in ?0..?9 ->
+          write_text(text, indent, options)
+          process_list(<<d1, ?., ?\s>>, item, rest, count, indent, options)
+        <<d1, d2, ?., ?\s, item :: binary>> when d1 in ?0..?9 and d2 in ?0..?9 ->
+          write_text(text, indent, options)
+          process_list(<<d1, d2, ?., ?\s>>, item, rest, count, indent, options)
        _ ->
-        process_text(rest, [line], indent, false, options)
+          process(rest, [stripped | text], indent, options)
      end
    end
-
-  defp strip_spaces(" " <> line, acc) do
-    strip_spaces(line, acc + 1)
-  end
-
-  defp strip_spaces(rest, acc) do
-    {rest, acc}
  end

  ## Headings
@@ -110,91 +124,81 @@ defmodule IO.ANSI.Docs do

  defp write_h2(heading, options) do
    write(:doc_headings, heading, options)
+    newline_after_block
  end

  defp write_h3(heading, indent, options) do
    IO.write(indent)
    write(:doc_headings, heading, options)
+    newline_after_block
  end

  ## Lists

-  defp process_list(line, rest, count, indent, options) do
-    IO.write indent <> "• "
-    {contents, rest, done} = process_list_next(rest, count, false, [])
-    process_text(contents, [line], indent <> "  ", true, options)
-    if done, do: IO.puts(IO.ANSI.reset)
-    process(rest, indent, options)
+  defp process_list(entry, line, rest, count, indent, options) do
+    # The first list always win some extra padding
+    if indent == "", do: entry = "  " <> entry
+    new_indent = indent <> String.duplicate(" ", String.length(entry))
+
+    {contents, rest, done} = process_list_next(rest, count, byte_size(new_indent), [])
+    process(contents, [indent <> entry <> line, :no_wrap], new_indent, options)
+
+    if done, do: newline_after_block()
+    process(rest, [], indent, options)
  end

-  # Process the thing after a list item entry. It can be either:
-  #
-  # * Continuation of the list
-  # * A nested list
-  # * The end of the list
-  #
-  defp process_list_next([" " <> _ = line | rest], count, _done, acc) do
-    case list_next(line, count) do
-      :done    -> {Enum.reverse(acc), [line|rest], false}
-      chopped  -> process_list_next(rest, count, false, [chopped|acc])
+  defp process_list_next([line | rest], count, max, acc) do
+    {stripped, next_count} = strip_spaces(line, 0, max)
+    case process_list_next_kind(stripped, rest, count, next_count) do
+      :next -> process_list_next(rest, count, max, [stripped | acc])
+      :done -> {Enum.reverse(acc), [line | rest], true}
+      :list -> {Enum.reverse(acc), [line | rest], false}
    end
  end

-  defp process_list_next([<<bullet, ?\s, _ :: binary>> | _] = rest, _count, _done, acc) when bullet in @bullets do
-    {Enum.reverse(acc), rest, false}
+  defp process_list_next([], _count, _max, acc) do
+    {Enum.reverse(acc), [], true}
  end

-  defp process_list_next(["" | rest], count, _done, acc) do
-    process_list_next(rest, count, true, [""|acc])
-  end
-
-  defp process_list_next(rest, _count, done, acc) do
-    {Enum.reverse(acc), rest, done}
-  end
-
-  defp list_next(<<bullet, ?\s, _ :: binary>>, 0) when bullet in @bullets, do: :done
-  defp list_next(line, 0),          do: chop(line, 2)
-  defp list_next(" " <> line, acc), do: list_next(line, acc - 1)
-  defp list_next(line, _acc),       do: line
-
-  defp chop(" " <> line, acc) when acc > 0, do: chop(line, acc - 1)
-  defp chop(line, _acc), do: line
-
-  ## Text (paragraphs / lists)
-
-  defp process_text(doc=["" | _], para, indent, from_list, options) do
-    write_text(Enum.reverse(para), indent, from_list, options)
-    process(doc, indent, options)
-  end
-
-  defp process_text([], para, indent, from_list, options) do
-    write_text(Enum.reverse(para), indent, from_list, options)
-  end
-
-  defp process_text([line | rest], para, indent, true, options) do
-    {stripped, count} = strip_spaces(line, 0)
-    case stripped do
-      <<bullet, ?\s, item :: binary>> when bullet in @bullets ->
-        write_text(Enum.reverse(para), indent, true, options)
-        process_list(item, rest, count, indent, options)
+  defp process_list_next_kind(stripped, rest, count, next_count) do
+    case {stripped, rest} do
+      {<<bullet, ?\s, _ :: binary>>, _} when bullet in @bullets and next_count <= count ->
+        :list
+      {<<d1, ?., ?\s, _ :: binary>>, _} when d1 in ?0..?9 and next_count <= count ->
+        :list
+      {<<d1, d2, ?., ?\s, _ :: binary>>, _} when d1 in ?0..?9 and d2 in ?0..?9 and next_count <= count ->
+        :list
+      {"", [" " <> _ | _]} ->
+        :next
+      {"", _} ->
+        :done
      _ ->
-        process_text(rest, [line | para], indent, true, options)
+        :next
    end
  end

-  defp process_text([line | rest], para, indent, from_list, options) do
-    process_text(rest, [line | para], indent, from_list, options)
+  ## Text
+
+  defp write_text(text, indent, options) do
+    case Enum.reverse(text) do
+      [:no_wrap|rest] -> write_text(rest, indent, options, true)
+      rest -> write_text(rest, indent, options, false)
+    end
  end

-  defp write_text(lines, indent, from_list, options) do
+  defp write_text([], _indent, _options, _no_wrap) do
+    :ok
+  end
+
+  defp write_text(lines, indent, options, no_wrap) do
    lines
    |> Enum.join(" ")
    |> handle_links
-    |> handle_inline(nil, [], [], options)
+    |> handle_inline(options)
    |> String.split(~r{\s})
-    |> write_with_wrap(options[:width] - byte_size(indent), indent, from_list)
+    |> write_with_wrap(options[:width] - byte_size(indent), indent, no_wrap)

-    unless from_list, do: IO.puts(IO.ANSI.reset)
+    unless no_wrap, do: newline_after_block()
  end

  ## Code blocks
@@ -214,18 +218,114 @@ defmodule IO.ANSI.Docs do

  defp process_code(rest, code, indent, options) do
    write_code(code, indent, options)
-    process(rest, indent, options)
+    process(rest, [], indent, options)
  end

  defp write_code(code, indent, options) do
    write(:doc_code, "#{indent}┃ #{Enum.join(Enum.reverse(code), "\n#{indent}┃ ")}", options)
+    newline_after_block
+  end
+
+  ## Tables
+
+  defp process_table(lines, indent, options) do
+    {table, rest} = Enum.split_while(lines, &is_table_line?/1)
+    table_lines(table, options)
+    newline_after_block
+    process(rest, [], indent, options)
+  end
+
+  defp table_lines(lines, options) do
+    lines = Enum.map(lines, &split_into_columns(&1, options))
+    count = Enum.map(lines, &length/1) |> Enum.max
+    lines = Enum.map(lines, &pad_to_number_of_columns(&1, count))
+
+    widths = for line <- lines, do:
+              (for {_col, length} <- line, do: length)
+
+    col_widths = Enum.reduce(widths,
+                             List.duplicate(0, count),
+                             &max_column_widths/2)
+
+    render_table(lines, col_widths, options)
+  end
+
+  defp split_into_columns(line, options) do
+    line
+    |> String.strip(?|)
+    |> String.strip()
+    |> String.split(~r/\s\|\s/)
+    |> Enum.map(&render_column(&1, options))
+  end
+
+  defp render_column(col, options) do
+    col = col
+          |> String.replace(~r/\\ \|/x, "|")
+          |> handle_links
+          |> handle_inline(options)
+    {col, length_without_escape(col, 0)}
+  end
+
+  defp pad_to_number_of_columns(cols, col_count),
+    do: cols ++ List.duplicate({"", 0}, col_count - length(cols))
+
+  defp max_column_widths(cols, widths),
+    do: Enum.zip(cols, widths) |> Enum.map(fn {a,b} -> max(a,b) end)
+
+  # If second line is heading separator, use the heading style on the first
+  defp render_table([first, second | rest], widths, options) do
+    combined = Enum.zip(first, widths)
+    if table_header?(second) do
+      draw_table_row(combined, options, :heading)
+      render_table(rest, widths, options)
+    else
+      draw_table_row(combined, options)
+      render_table([second | rest], widths, options)
+    end
+  end
+
+  defp render_table([first | rest], widths, options) do
+    combined = Enum.zip(first, widths)
+    draw_table_row(combined, options)
+    render_table(rest, widths, options)
+  end
+
+  defp render_table([], _, _),
+    do: nil
+
+  defp table_header?(row), do:
+    Enum.all?(row, fn {col, _} -> col =~ ~r/^:?-+:?$/ end)
+
+  defp draw_table_row(cols_and_widths, options, heading \\ false) do
+    columns =
+      Enum.map_join(cols_and_widths, " | ", fn {{col, length}, width} ->
+        col <> String.duplicate(" ", width - length)
+      end)
+
+    if heading do
+      write(:doc_table_heading, columns, options)
+    else
+      IO.puts columns
+    end
+  end
+
+  defp is_table_line?(line) do
+    Regex.match?(~r'''
+      ( ^ \s{0,3} \| (?: [^|]+ \|)+ \s* $ )
+    |
+      (\s \| \s)
+    '''x, line)
  end

  ## Helpers

+  defp strip_spaces(" " <> line, acc, max) when acc < max,
+    do: strip_spaces(line, acc + 1, max)
+  defp strip_spaces(rest, acc, _max),
+    do: {rest, acc}
+
  defp write(style, string, options) do
-    IO.puts color(style, options) <> string <> IO.ANSI.reset
-    IO.puts IO.ANSI.reset
+    IO.puts [color(style, options), string, IO.ANSI.reset]
  end

  defp write_with_wrap([], _available, _indent, _first) do
@@ -283,10 +383,8 @@ defmodule IO.ANSI.Docs do

  defp escape_underlines_in_link(text) do
    case Regex.match?(~r{.*(https?\S*)}, text) do
-      true ->
-        Regex.replace(~r{_}, text, "\\\\_")
-      _ ->
-        text
+      true -> Regex.replace(~r{_}, text, "\\\\_")
+      _    -> text
    end
  end

@@ -294,61 +392,104 @@ defmodule IO.ANSI.Docs do
    Regex.replace(~r{\[(.*?)\]\((.*?)\)}, text, "\\1 (\\2)")
  end

-  # Single inline quotes.
-  @single [?`, ?_, ?*]

-  # ` does not require space in between
-  @spaced [?_, ?*]
+  # We have four entries: **, *, _ and `.
+  #
+  # The first three behave the same while the last one is simpler
+  # when it comes to delimiters. But, since the first has two
+  # characters, we need to handle 3 cases:
+  #
+  # 1. **
+  # 2. _ and *
+  # 3. `
+  #
+  # Where the first two should have the same code but match differently.
+  @single [?_, ?*]

-  # Clauses for handling spaces
-  defp handle_inline(<<?*, ?*, ?\s, rest :: binary>>, nil, buffer, acc, options) do
-    handle_inline(rest, nil, [?\s, ?*, ?*|buffer], acc, options)
+  # Characters that can mark the beginning or the end of a word.
+  # Only support the most common ones at this moment.
+  @delimiters [?\s, ?', ?", ?!, ?@, ?#, ?$, ?%, ?^, ?&, ?-, ?+, ?(, ?), ?[, ?], ?{, ?}, ?<, ?>, ?.]
+
+  # Inline start
+
+  defp handle_inline(<<?*, ?*, rest :: binary>>, options) do
+    handle_inline(rest, ?d, ["**"], [], options)
  end

-  defp handle_inline(<<mark, ?\s, rest :: binary>>, nil, buffer, acc, options) when mark in @spaced do
-    handle_inline(rest, nil, [?\s, mark|buffer], acc, options)
+  defp handle_inline(<<mark, rest :: binary>>, options) when mark in @single do
+    handle_inline(rest, mark, [<<mark>>], [], options)
  end

-  defp handle_inline(<<?\s, ?*, ?*, rest :: binary>>, limit, buffer, acc, options) do
-    handle_inline(rest, limit, [?*, ?*, ?\s|buffer], acc, options)
+  defp handle_inline(rest, options) do
+    handle_inline(rest, nil, [], [], options)
  end

-  defp handle_inline(<<?\s, mark, rest :: binary>>, limit, buffer, acc, options) when mark in @spaced do
-    handle_inline(rest, limit, [mark, ?\s|buffer], acc, options)
+  # Inline delimiters
+
+  defp handle_inline(<<delimiter, ?*, ?*, rest :: binary>>, nil, buffer, acc, options)
+      when rest != "" and delimiter in @delimiters do
+    handle_inline(rest, ?d, ["**"], [delimiter, Enum.reverse(buffer)|acc], options)
+  end
+
+  defp handle_inline(<<delimiter, mark, rest :: binary>>, nil, buffer, acc, options)
+      when rest != "" and delimiter in @delimiters and mark in @single do
+    handle_inline(rest, mark, [<<mark>>], [delimiter, Enum.reverse(buffer)|acc], options)
+  end
+
+  defp handle_inline(<<?`, rest :: binary>>, nil, buffer, acc, options)
+      when rest != "" do
+    handle_inline(rest, ?`, ["`"], [Enum.reverse(buffer)|acc], options)
  end

  # Clauses for handling escape
+
+  defp handle_inline(<<?\\, ?\\, ?*, ?*, rest :: binary>>, nil, buffer, acc, options)
+      when rest != "" do
+    handle_inline(rest, ?d, ["**"], [?\\, Enum.reverse(buffer)|acc], options)
+  end
+
+  defp handle_inline(<<?\\, ?\\, mark, rest :: binary>>, nil, buffer, acc, options)
+      when rest != "" and mark in @single do
+    handle_inline(rest, mark, [<<mark>>], [?\\, Enum.reverse(buffer)|acc], options)
+  end
+
  defp handle_inline(<<?\\, ?\\, rest :: binary>>, limit, buffer, acc, options) do
    handle_inline(rest, limit, [?\\|buffer], acc, options)
  end

-  defp handle_inline(<<?\\, ?*, ?*, rest :: binary>>, limit, buffer, acc, options) do
-    handle_inline(rest, limit, [?*, ?*|buffer], acc, options)
-  end
-
-  # A escape is not valid inside `
+  # An escape is not valid inside `
  defp handle_inline(<<?\\, mark, rest :: binary>>, limit, buffer, acc, options)
-      when mark in [?_, ?*, ?`] and not(mark == limit and mark == ?`) do
+      when not(mark == limit and mark == ?`) do
    handle_inline(rest, limit, [mark|buffer], acc, options)
  end

-  # Inline start
-  defp handle_inline(<<?*, ?*, rest :: binary>>, nil, buffer, acc, options) when rest != "" do
-    handle_inline(rest, ?d, ["**"], [Enum.reverse(buffer)|acc], options)
-  end
-
-  defp handle_inline(<<mark, rest :: binary>>, nil, buffer, acc, options) when rest != "" and mark in @single do
-    handle_inline(rest, mark, [<<mark>>], [Enum.reverse(buffer)|acc], options)
-  end
-
  # Inline end
-  defp handle_inline(<<?*, ?*, rest :: binary>>, ?d, buffer, acc, options) do
+
+  defp handle_inline(<<?*, ?*, delimiter, rest :: binary>>, ?d, buffer, acc, options)
+      when delimiter in @delimiters do
+    handle_inline(<<delimiter, rest :: binary>>, nil, [], [inline_buffer(buffer, options)|acc], options)
+  end
+
+  defp handle_inline(<<mark, delimiter, rest :: binary>>, mark, buffer, acc, options)
+      when delimiter in @delimiters and mark in @single do
+    handle_inline(<<delimiter, rest :: binary>>, nil, [], [inline_buffer(buffer, options)|acc], options)
+  end
+
+  defp handle_inline(<<?*, ?*, rest:: binary>>, ?d, buffer, acc, options)
+      when rest == "" do
+    handle_inline(<<>>, nil, [], [inline_buffer(buffer, options)|acc], options)
+  end
+
+  defp handle_inline(<<mark, rest :: binary>>, mark, buffer, acc, options)
+      when rest == "" and mark in @single do
+    handle_inline(<<>>, nil, [], [inline_buffer(buffer, options)|acc], options)
+  end
+
+  defp handle_inline(<<?`, rest :: binary>>, ?`, buffer, acc, options) do
    handle_inline(rest, nil, [], [inline_buffer(buffer, options)|acc], options)
  end

-  defp handle_inline(<<mark, rest :: binary>>, mark, buffer, acc, options) when mark in @single do
-    handle_inline(rest, nil, [], [inline_buffer(buffer, options)|acc], options)
-  end
+  # Catch all

  defp handle_inline(<<char, rest :: binary>>, mark, buffer, acc, options) do
    handle_inline(rest, mark, [char|buffer], acc, options)
@@ -363,14 +504,19 @@ defmodule IO.ANSI.Docs do
    [color_for(h, options)|t]
  end

-  defp color_for("`", colors),  do: color(:doc_inline_code, colors)
-  defp color_for("_", colors),  do: color(:doc_underline, colors)
-  defp color_for("*", colors),  do: color(:doc_bold, colors)
-  defp color_for("**", colors), do: color(:doc_bold, colors)
+  defp color_for(mark, colors) do
+    case mark do
+      "`"  -> color(:doc_inline_code, colors)
+      "_"  -> color(:doc_underline, colors)
+      "*"  -> color(:doc_bold, colors)
+      "**" -> color(:doc_bold, colors)
+    end
+  end

  defp color(style, colors) do
    color = colors[style]
-    enabled = colors[:enabled]
-    IO.ANSI.escape_fragment("%{#{color}}", enabled)
+    IO.ANSI.format_fragment(color, colors[:enabled])
  end
+
+  defp newline_after_block, do: IO.puts(IO.ANSI.reset)
 end
@@ -22,6 +22,8 @@ defmodule IO.Stream do

  defstruct device: nil, raw: true, line_or_bytes: :line

+  @type t :: %__MODULE__{}
+
  @doc false
  def __build__(device, raw, line_or_bytes) do
    %IO.Stream{device: device, raw: raw, line_or_bytes: line_or_bytes}
@@ -55,7 +57,7 @@ defmodule IO.Stream do
          true  -> &IO.each_binstream(&1, line_or_bytes)
          false -> &IO.each_stream(&1, line_or_bytes)
        end
-      Stream.unfold(device, next_fun).(acc, fun)
+      Stream.resource(fn -> device end, next_fun, &(&1)).(acc, fun)
    end

    def count(_stream) do
@@ -150,9 +150,9 @@ defmodule Kernel do
      3

  """
-  @spec byte_size(bitstring) :: non_neg_integer
-  def byte_size(bitstring) do
-    :erlang.byte_size(bitstring)
+  @spec byte_size(binary) :: non_neg_integer
+  def byte_size(binary) do
+    :erlang.byte_size(binary)
  end

  @doc """
@@ -183,9 +183,56 @@ defmodule Kernel do

  ## Examples

+  When a process reaches its end, by default it exits with
+  reason `:normal`. You can also call it explicitly if you
+  want to terminate a process but not signal any failure:
+
      exit(:normal)
+
+  In case something goes wrong, you can also use `exit/1` with
+  a different reason:
+
      exit(:seems_bad)

+  If the reason is not `:normal`, all linked process to the
+  exited process will crash (unless they are trapping exits).
+
+  ## OTP exits
+
+  Exits are used by OTP to determine if a process exited abnormally
+  or not. The following exits are considered "normal":
+
+    * `exit(:normal)`
+    * `exit(:shutdown)`
+    * `exit({:shutdown, term})`
+
+  Exiting with any other reason is considered abnormal and treated
+  as a crash. This means the default supervisor behaviour kicks in,
+  error reports are emitted, etc.
+
+  This behaviour is relied on in many different places. For example,
+  `ExUnit` uses `exit(:shutdown)` when exiting the test process to
+  signal linked processes, supervision trees and so on to politely
+  shutdown too.
+
+  ## CLI exits
+
+  Building on top of the exit signals mentioned above, if the
+  process started by the command line exits with any of the three
+  reasons above, its exit is considered normal and the Operating
+  System process will exit with status 0.
+
+  It is, however, possible to customize the Operating System exit
+  signal by invoking:
+
+      exit({:shutdown, integer})
+
+  This will cause the OS process to exit with the status given by
+  `integer` while signaling all linked OTP processes to politely
+  shutdown.
+
+  Any other exit reason will cause the OS process to exit with
+  status `1` and linked OTP processes to crash.
  """
  @spec exit(term) :: no_return
  def exit(reason) do
@@ -838,11 +885,6 @@ defmodule Kernel do
    :erlang.--(left, right)
  end

-  @doc false
-  def left xor right do
-    :erlang.xor(left, right)
-  end
-
  @doc """
  Boolean not. Argument must be a boolean.

@@ -1344,7 +1386,14 @@ defmodule Kernel do
      iex> "abcd" =~ "ad"
      false

+      iex> "abcd" =~ ""
+      true
+
  """
+
+  @spec (String.t =~ (String.t | Regex.t)) :: boolean
+  def left =~ "" when is_binary(left), do: true
+
  def left =~ right when is_binary(left) and is_binary(right) do
    :binary.match(left, right) != :nomatch
  end
@@ -1372,14 +1421,26 @@ defmodule Kernel do
      iex> inspect [1, 2, 3, 4, 5], limit: 3
      "[1, 2, 3, ...]"

-      iex> inspect("josé" <> <<0>>)
-      "<<106, 111, 115, 195, 169, 0>>"
+      iex> inspect("olá" <> <<0>>)
+      "<<111, 108, 195, 161, 0>>"

-      iex> inspect("josé" <> <<0>>, binaries: :as_strings)
-      "\"josé\\000\""
+      iex> inspect("olá" <> <<0>>, binaries: :as_strings)
+      "\"olá\\0\""

-      iex> inspect("josé", binaries: :as_binaries)
-      "<<106, 111, 115, 195, 169>>"
+      iex> inspect("olá", binaries: :as_binaries)
+      "<<111, 108, 195, 161>>"
+
+      iex> inspect('bar')
+      "'bar'"
+
+      iex> inspect([0|'bar'])
+      "[0, 98, 97, 114]"
+
+      iex> inspect(100, base: :octal)
+      "0o144"
+
+      iex> inspect(100, base: :hex)
+      "0x64"

  Note that the inspect protocol does not necessarily return a valid
  representation of an Elixir term. In such cases, the inspected result
@@ -1396,7 +1457,9 @@ defmodule Kernel do
      true  -> opts.width
      false -> :infinity
    end
-    Inspect.Algebra.pretty(Inspect.Algebra.to_doc(arg, opts), limit)
+    IO.iodata_to_binary(
+      Inspect.Algebra.format(Inspect.Algebra.to_doc(arg, opts), limit)
+    )
  end

  @doc """
@@ -1415,18 +1478,18 @@ defmodule Kernel do
  ## Example

      defmodule User do
-        defstruct name: "jose"
+        defstruct name: "john"
      end

      struct(User)
-      #=> %User{name: "jose"}
+      #=> %User{name: "john"}

-      opts = [name: "eric"]
+      opts = [name: "meg"]
      user = struct(User, opts)
-      #=> %User{name: "eric"}
+      #=> %User{name: "meg"}

      struct(user, unknown: "value")
-      #=> %User{name: "eric"}
+      #=> %User{name: "meg"}

  """
  @spec struct(module | map, Enum.t) :: map
@@ -1453,47 +1516,77 @@ defmodule Kernel do
  Gets a value from a nested structure.

  Uses the `Access` protocol to traverse the structures
-  according to the given `keys`.
+  according to the given `keys`, unless the `key` is a
+  function.
+
+  If a key is a function, the function will be invoked
+  passing three arguments, the operation (`:get`), the
+  data to be accessed, and a function to be invoked next.
+
+  This means `get_in/2` can be extended to provide
+  custom lookups. The downside is that functions cannot be
+  stored as keys in the accessed data structures.

  ## Examples

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> get_in(users, ["josé", :age])
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> get_in(users, ["john", :age])
      27

  In case any of entries in the middle returns `nil`, `nil` will be returned
  as per the Access protocol:

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
      iex> get_in(users, ["unknown", :age])
      nil

+  When one of the keys is a function, the function is invoked.
+  In the example below, we use a function to get all the maps
+  inside a list:
+
+      iex> users = [%{name: "john", age: 27}, %{name: "meg", age: 23}]
+      iex> all = fn :get, data, next -> Enum.map(data, next) end
+      iex> get_in(users, [all, :age])
+      [27, 23]
+
+  If the previous value before invoking the function is nil,
+  the function *will* receive nil as a value and must handle it
+  accordingly.
  """
  @spec get_in(Access.t, nonempty_list(term)) :: term
  def get_in(data, keys)
-  def get_in(nil, list) when is_list(list), do: nil
-  def get_in(data, [h]),                    do: Access.get(data, h)
-  def get_in(data, [h|t]),                  do: get_in(Access.get(data, h), t)
+
+  def get_in(data, [h]) when is_function(h),
+    do: h.(:get, data, &(&1))
+  def get_in(data, [h|t]) when is_function(h),
+    do: h.(:get, data, &get_in(&1, t))
+
+  def get_in(nil, [_]),
+    do: nil
+  def get_in(nil, [_|t]),
+    do: get_in(nil, t)
+
+  def get_in(data, [h]),
+    do: Access.get(data, h)
+  def get_in(data, [h|t]),
+    do: get_in(Access.get(data, h), t)

  @doc """
  Puts a value in a nested structure.

  Uses the `Access` protocol to traverse the structures
-  according to the given `keys`.
+  according to the given `keys`, unless the `key` is a
+  function. If the key is a function, it will be invoked
+  as specified in `get_and_update_in/3`.

  ## Examples

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> put_in(users, ["josé", :age], 28)
-      %{"josé" => %{age: 28}, "eric" => %{age: 23}}
-
-  In case any of entries in the middle returns `nil`, a map is dynamically
-  created:
-
-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> put_in(users, ["dave", :age], 13)
-      %{"josé" => %{age: 27}, "eric" => %{age: 23}, "dave" => %{age: 13}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> put_in(users, ["john", :age], 28)
+      %{"john" => %{age: 28}, "meg" => %{age: 23}}

+  In case any of entries in the middle returns `nil`,
+  an error will be raised when trying to access it next.
  """
  @spec put_in(Access.t, nonempty_list(term), term) :: Access.t
  def put_in(data, keys, value) do
@@ -1504,21 +1597,18 @@ defmodule Kernel do
  Updates a key in a nested structure.

  Uses the `Access` protocol to traverse the structures
-  according to the given `keys`.
+  according to the given `keys`, unless the `key` is a
+  function. If the key is a function, it will be invoked
+  as specified in `get_and_update_in/3`.

  ## Examples

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> update_in(users, ["josé", :age], &(&1 + 1))
-      %{"josé" => %{age: 28}, "eric" => %{age: 23}}
-
-  In case any of entries in the middle returns `nil`, a map is dynamically
-  created:
-
-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> update_in(users, ["dave", :age], &((&1 || 0) + 1))
-      %{"josé" => %{age: 27}, "eric" => %{age: 23}, "dave" => %{age: 1}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> update_in(users, ["john", :age], &(&1 + 1))
+      %{"john" => %{age: 28}, "meg" => %{age: 23}}

+  In case any of entries in the middle returns `nil`,
+  an error will be raised when trying to access it next.
  """
  @spec update_in(Access.t, nonempty_list(term), (term -> term)) :: Access.t
  def update_in(data, keys, fun) do
@@ -1528,9 +1618,20 @@ defmodule Kernel do
  @doc """
  Gets a value and updates a nested structure.

-  It expects a tuple to be returned, containing the value retrieved
-  and the update one. Uses the `Access` protocol to traverse the
-  structures according to the given `keys`.
+  It expects a tuple to be returned, containing the value
+  retrieved and the update one.
+
+  Uses the `Access` protocol to traverse the structures
+  according to the given `keys`, unless the `key` is a
+  function.
+
+  If a key is a function, the function will be invoked
+  passing three arguments, the operation (`:get_and_update`),
+  the data to be accessed, and a function to be invoked next.
+
+  This means `get_and_update_in/3` can be extended to provide
+  custom lookups. The downside is that functions cannot be stored
+  as keys in the accessed data structures.

  ## Examples

@@ -1539,27 +1640,38 @@ defmodule Kernel do
  update it at the same time. For example, it could be used to increase
  the age of a user by one and return the previous age in one pass:

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> get_and_update_in(users, ["josé", :age], &{&1, &1 + 1})
-      {27, %{"josé" => %{age: 28}, "eric" => %{age: 23}}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> get_and_update_in(users, ["john", :age], &{&1, &1 + 1})
+      {27, %{"john" => %{age: 28}, "meg" => %{age: 23}}}

-  In case any of entries in the middle returns `nil`, a map is dynamically
-  created:
+  When one of the keys is a function, the function is invoked.
+  In the example below, we use a function to get and increment all
+  ages inside a list:

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> get_and_update_in(users, ["dave", :age], &{&1, 13})
-      {nil, %{"josé" => %{age: 27}, "eric" => %{age: 23}, "dave" => %{age: 13}}}
+      iex> users = [%{name: "john", age: 27}, %{name: "meg", age: 23}]
+      iex> all = fn :get_and_update, data, next ->
+      ...>   Enum.map(data, next) |> :lists.unzip
+      ...> end
+      iex> get_and_update_in(users, [all, :age], &{&1, &1 + 1})
+      {[27, 23], [%{name: "john", age: 28}, %{name: "meg", age: 24}]}

+  If the previous value before invoking the function is nil,
+  the function *will* receive `nil` as a value and must handle it
+  accordingly (be it by failing or providing a sane default).
  """
  @spec get_and_update_in(Access.t, nonempty_list(term),
                          (term -> {get, term})) :: {get, Access.t} when get: var
  def get_and_update_in(data, keys, fun)

-  def get_and_update_in(nil, list, fun), do: get_and_update_in(%{}, list, fun)
-  def get_and_update_in(data, [h], fun), do: Access.get_and_update(data, h, fun)
-  def get_and_update_in(data, [h|t], fun) do
-    Access.get_and_update(data, h, &get_and_update_in(&1, t, fun))
-  end
+  def get_and_update_in(data, [h], fun) when is_function(h),
+    do: h.(:get_and_update, data, fun)
+  def get_and_update_in(data, [h|t], fun) when is_function(h),
+    do: h.(:get_and_update, data, &get_and_update_in(&1, t, fun))
+
+  def get_and_update_in(data, [h], fun),
+    do: Access.get_and_update(data, h, fun)
+  def get_and_update_in(data, [h|t], fun),
+    do: Access.get_and_update(data, h, &get_and_update_in(&1, t, fun))

  @doc """
  Puts a value in a nested structure via the given `path`.
@@ -1579,13 +1691,13 @@ defmodule Kernel do

  ## Examples

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> put_in(users["josé"][:age], 28)
-      %{"josé" => %{age: 28}, "eric" => %{age: 23}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> put_in(users["john"][:age], 28)
+      %{"john" => %{age: 28}, "meg" => %{age: 23}}

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> put_in(users["josé"].age, 28)
-      %{"josé" => %{age: 28}, "eric" => %{age: 23}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> put_in(users["john"].age, 28)
+      %{"john" => %{age: 28}, "meg" => %{age: 23}}

  """
  defmacro put_in(path, value) do
@@ -1612,13 +1724,13 @@ defmodule Kernel do

  ## Examples

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> update_in(users["josé"][:age], &(&1 + 1))
-      %{"josé" => %{age: 28}, "eric" => %{age: 23}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> update_in(users["john"][:age], &(&1 + 1))
+      %{"john" => %{age: 28}, "meg" => %{age: 23}}

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> update_in(users["josé"].age, &(&1 + 1))
-      %{"josé" => %{age: 28}, "eric" => %{age: 23}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> update_in(users["john"].age, &(&1 + 1))
+      %{"john" => %{age: 28}, "meg" => %{age: 23}}

  """
  defmacro update_in(path, fun) do
@@ -1644,9 +1756,9 @@ defmodule Kernel do

  ## Examples

-      iex> users = %{"josé" => %{age: 27}, "eric" => %{age: 23}}
-      iex> get_and_update_in(users["josé"][:age], &{&1, &1 + 1})
-      {27, %{"josé" => %{age: 28}, "eric" => %{age: 23}}}
+      iex> users = %{"john" => %{age: 27}, "meg" => %{age: 23}}
+      iex> get_and_update_in(users["john"].age, &{&1, &1 + 1})
+      {27, %{"john" => %{age: 28}, "meg" => %{age: 23}}}

  ## Paths

@@ -1661,15 +1773,15 @@ defmodule Kernel do

  Here are some valid paths:

-      users["josé"][:age]
-      users["josé"].age
-      User.all["josé"].age
-      all_users()["josé"].age
+      users["john"][:age]
+      users["john"].age
+      User.all["john"].age
+      all_users()["john"].age

  Here are some invalid ones:

      # Does a remote call after the initial value
-      users["josé"].do_something(arg1, arg2)
+      users["john"].do_something(arg1, arg2)

      # Does not access any field
      users
@@ -1690,7 +1802,7 @@ defmodule Kernel do
  defp nest_get_and_update_in(h, [{:access, key}|t], fun) do
    quote do
      Access.get_and_update(
-        case(unquote(h), do: (nil -> %{}; o -> o)),
+        unquote(h),
        unquote(key),
        unquote(nest_get_and_update_in(t, fun))
      )
@@ -1708,13 +1820,15 @@ defmodule Kernel do
  end

  defp unnest({{:., _, [expr, key]}, _, []}, acc, kind)
-      when is_tuple(expr) and elem(expr, 0) != :__aliases__ and elem(expr, 0) != :__MODULE__ do
+      when is_tuple(expr) and
+           :erlang.element(1, expr) != :__aliases__ and
+           :erlang.element(1, expr) != :__MODULE__ do
    unnest(expr, [{:map, key}|acc], kind)
  end

  defp unnest(other, [], kind) do
    raise ArgumentError,
-      "expected expression given to #{kind} to access at least one field, got: #{Macro.to_string other}"
+      "expected expression given to #{kind} to access at least one element, got: #{Macro.to_string other}"
  end

  defp unnest(other, acc, kind) do
@@ -1723,14 +1837,14 @@ defmodule Kernel do
      false ->
        raise ArgumentError,
          "expression given to #{kind} must start with a variable, local or remote call " <>
-          "and be followed by field access, got: #{Macro.to_string other}"
+          "and be followed by an element access, got: #{Macro.to_string other}"
    end
  end

  defp proper_start?({{:., _, [expr, _]}, _, _args})
    when is_atom(expr)
-    when elem(expr, 0) == :__aliases__
-    when elem(expr, 0) == :__MODULE__, do: true
+    when :erlang.element(1, expr) == :__aliases__
+    when :erlang.element(1, expr) == :__MODULE__, do: true

  defp proper_start?({atom, _, _args})
    when is_atom(atom), do: true
@@ -1776,20 +1890,20 @@ defmodule Kernel do

  ## Examples

-      iex> nil?(1)
+      iex> is_nil(1)
      false

-      iex> nil?(nil)
+      iex> is_nil(nil)
      true

  """
-  defmacro nil?(x) do
+  defmacro is_nil(x) do
    quote do: unquote(x) == nil
  end

  @doc """
-  A convenient macro that checks if the right side matches
-  the left side. The left side is allowed to be a match pattern.
+  A convenience macro that checks if the right side (an expression)
+  matches the left side (a pattern).

  ## Examples

@@ -1894,10 +2008,7 @@ defmodule Kernel do

        case is_list(args) and length(args) == 1 and typespec(name) do
          false ->
-            case name == :typedoc and not bootstraped?(Kernel.Typespec) do
-              true  -> nil
-              false -> do_at(args, name, function?, __CALLER__)
-            end
+            do_at(args, name, function?, __CALLER__)
          macro ->
            case bootstraped?(Kernel.Typespec) do
              false -> nil
@@ -1911,7 +2022,7 @@ defmodule Kernel do
  defp do_at([arg], name, function?, env) do
    case function? do
      true ->
-        raise ArgumentError, "cannot dynamically set attribute @#{name} inside function"
+        raise ArgumentError, "cannot set attribute @#{name} inside function/macro"
      false ->
        case name do
          :behavior ->
@@ -1932,7 +2043,14 @@ defmodule Kernel do
    case function? do
      true ->
        attr = Module.get_attribute(env.module, name, stack)
-        :erlang.element(1, :elixir_quote.escape(attr, false))
+        try do
+          :elixir_quote.escape(attr, false)
+        rescue
+          e in [ArgumentError] ->
+            raise ArgumentError, "cannot inject attribute @#{name} into function/macro because " <> Exception.message(e)
+        else
+          {val, _} -> val
+        end
      false ->
        escaped = case stack do
          [] -> []
@@ -1948,7 +2066,7 @@ defmodule Kernel do
  end

  defp warn_info([entry|_]) do
-    opts = elem(entry, tuple_size(entry) - 1)
+    opts = :erlang.element(tuple_size(entry), entry)
    Exception.format_file_line(Keyword.get(opts, :file), Keyword.get(opts, :line)) <> " "
  end

@@ -1964,8 +2082,9 @@ defmodule Kernel do
  defp typespec(_),         do: false

  @doc """
-  Returns the binding as a keyword list where the variable name
-  is the key and the variable value is the value.
+  Returns the binding for the given context as a keyword list.
+
+  The variable name is the key and the variable value is the value.

  ## Examples

@@ -1976,59 +2095,18 @@ defmodule Kernel do
      iex> binding()
      [x: 2]

-  """
-  defmacro binding() do
-    do_binding(nil, nil, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  @doc """
-  Receives a list of atoms at compilation time and returns the
-  binding of the given variables as a keyword list where the
-  variable name is the key and the variable value is the value.
-
-  In case a variable in the list does not exist in the binding,
-  it is not included in the returned result.
-
-  ## Examples
-
-      iex> x = 1
-      iex> binding([:x, :y])
-      [x: 1]
-
-  """
-  defmacro binding(list) when is_list(list) do
-    do_binding(list, nil, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  defmacro binding(context) when is_atom(context) do
-    do_binding(nil, context, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  @doc """
-  Receives a list of atoms at compilation time and returns the
-  binding of the given variables in the given context as a keyword
-  list where the variable name is the key and the variable value
-  is the value.
-
-  In case a variable in the list does not exist in the binding,
-  it is not included in the returned result.
-
-  ## Examples
-
-      iex> var!(x, :foo) = 1
-      iex> binding([:x, :y])
+      iex> binding(:foo)
      []
-      iex> binding([:x, :y], :foo)
+      iex> var!(x, :foo) = 1
+      1
+      iex> binding(:foo)
      [x: 1]

  """
-  defmacro binding(list, context) when is_list(list) and is_atom(context) do
-    do_binding(list, context, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  defp do_binding(list, context, vars, in_match) do
-    for {v, c} <- vars, c == context, list == nil or :lists.member(v, list) do
-      {v, wrap_binding(in_match, {v, [], c})}
+  defmacro binding(context \\ nil) do
+    in_match? = Macro.Env.in_match?(__CALLER__)
+    for {v, c} <- __CALLER__.vars, c == context do
+      {v, wrap_binding(in_match?, {v, [], c})}
    end
  end

@@ -2310,7 +2388,7 @@ defmodule Kernel do
  it is not loaded. Check `Code.ensure_loaded/1` for more
  information.
  """
-  @spec function_exported?(atom | tuple, atom, integer) :: boolean
+  @spec function_exported?(atom | tuple, atom, arity) :: boolean
  def function_exported?(module, function, arity) do
    :erlang.function_exported(module, function, arity)
  end
@@ -2561,7 +2639,7 @@ defmodule Kernel do

          # Generate the alias for this module definition
          {new, old} = module_nesting(env.module, full)
-          meta = [defined: full, context: true] ++ alias_meta(alias)
+          meta = [defined: full, context: env.module] ++ alias_meta(alias)

          {full, {:alias, meta, [old, [as: new, warn: false]]}}
        false ->
@@ -2819,97 +2897,59 @@ defmodule Kernel do

  ## Types

-  `defstruct` automatically generates a type `t` unless one exists.
-  The following definition:
+  It is recommended to define types for structs, by convention this type
+  is called `t`. To define a struct in a type the struct literal syntax
+  is used:

      defmodule User do
-        defstruct name: "José" :: String.t,
-                  age: 25 :: integer
+        defstruct name: "john", age: 25
+        @type t :: %User{name: String.t, age: integer}
      end

-  Generates a type as follows:
+  It is recommended to only use the struct syntax when defining the struct's
+  type. When referring to another struct use `User.t`, not `%User{}`. Fields
+  in the struct not included in the type defaults to `term`.

-      @type t :: %User{name: String.t, age: integer}
-
-  In case a struct does not declare a field type, it defaults to `term`.
+  Private structs that are not used outside its module should use the private
+  type attribute `@typep`. Public structs whose internal structure is private
+  to the local module (you are not allowed to pattern match it or directly
+  access fields) should use the `@opaque` attribute. Structs whose internal
+  structure is public should use `@type`.
  """
-  defmacro defstruct(kv) do
-    {fields, types} = split_fields_and_types(kv)
-
-    fields =
+  defmacro defstruct(fields) do
    quote bind_quoted: [fields: fields] do
      fields = :lists.map(fn
-          { key, _ } = pair when is_atom(key) -> pair
-          key when is_atom(key) -> { key, nil }
-          other -> raise ArgumentError, "struct field names must be atoms, got: #{inspect other}"
+        {key, val} when is_atom(key) ->
+          try do
+            Macro.escape(val)
+          rescue
+            e in [ArgumentError] ->
+              raise ArgumentError, "invalid value for struct field #{key}, " <> Exception.message(e)
+          else
+            _ -> {key, val}
+          end
+        key when is_atom(key) ->
+          {key, nil}
+        other ->
+          raise ArgumentError, "struct field names must be atoms, got: #{inspect other}"
      end, fields)

      @struct :maps.put(:__struct__, __MODULE__, :maps.from_list(fields))

      case Module.get_attribute(__MODULE__, :derive) do
-          [] ->
-            :ok
-          derive ->
-            Protocol.__derive__(derive, __MODULE__, __ENV__)
+        [] -> :ok
+        derive -> Protocol.__derive__(derive, __MODULE__, __ENV__)
      end

-        @spec __struct__() :: t
+      @spec __struct__() :: %__MODULE__{}
      def __struct__() do
        @struct
      end
-      end

-    types =
-      case bootstraped?(Kernel.Typespec) do
-        true when types == [] ->
-          quote unquote: false do
-            unless Kernel.Typespec.defines_type?(__MODULE__, :t, 0) do
-              types = :lists.map(fn {key, _} ->
-                {key, quote(do: term)}
-              end, fields)
-              @type t :: %{unquote_splicing(types), __struct__: __MODULE__}
-            end
-          end
-        true ->
-          quote do
-            unless Kernel.Typespec.defines_type?(__MODULE__, :t, 0) do
-              @type t :: %{unquote_splicing(types), __struct__: __MODULE__}
-            end
-          end
-        false ->
-          nil
-      end
-
-    quote do
-      unquote(fields)
-      unquote(types)
      fields
    end
  end

-  defp split_fields_and_types(kv) do
-    case Keyword.keyword?(kv) do
-      true  -> split_fields_and_types(kv, [], [])
-      false -> {kv, []}
-    end
-  end
-
-  defp split_fields_and_types([{field, {:::, _, [default, type]}}|t], fields, types) do
-    split_fields_and_types(t, [{field, default}|fields], [{field, type}|types])
-  end
-
-  defp split_fields_and_types([{field, default}|t], fields, types) do
-    split_fields_and_types(t, [{field, default}|fields], [{field, quote(do: term)}|types])
-  end
-
-  defp split_fields_and_types([field|t], fields, types) do
-    split_fields_and_types(t, [field|fields], [{field, quote(do: term)}|types])
-  end
-
-  defp split_fields_and_types([], fields, types) do
-    {:lists.reverse(fields), :lists.reverse(types)}
-  end
-
  @doc ~S"""
  Defines an exception.

@@ -2970,7 +3010,7 @@ defmodule Kernel do
      @behaviour Exception
      fields = defstruct unquote(fields)

-      @spec exception(term) :: t
+      @spec exception(Keyword.t) :: Exception.t
      def exception(args) when is_list(args) do
        Kernel.struct(__struct__, args)
      end
@@ -2978,7 +3018,7 @@ defmodule Kernel do
      defoverridable exception: 1

      if Keyword.has_key?(fields, :message) do
-        @spec message(t) :: String.t
+        @spec message(Exception.t) :: String.t
        def message(exception) do
          exception.message
        end
@@ -3309,7 +3349,7 @@ defmodule Kernel do

  ## Sigils

-  @doc """
+  @doc ~S"""
  Handles the sigil ~S. It simply returns a string
  without escaping characters and without interpolations.

@@ -3318,15 +3358,15 @@ defmodule Kernel do
      iex> ~S(foo)
      "foo"

-      iex> ~S(f\#{o}o)
-      "f\\\#{o}o"
+      iex> ~S(f#{o}o)
+      "f\#{o}o"

  """
  defmacro sigil_S(string, []) do
    string
  end

-  @doc """
+  @doc ~S"""
  Handles the sigil ~s. It returns a string as if it was double quoted
  string, unescaping characters and replacing interpolations.

@@ -3335,15 +3375,18 @@ defmodule Kernel do
      iex> ~s(foo)
      "foo"

-      iex> ~s(f\#{:o}o)
+      iex> ~s(f#{:o}o)
      "foo"

+      iex> ~s(f\#{:o}o)
+      "f\#{:o}o"
+
  """
  defmacro sigil_s({:<<>>, line, pieces}, []) do
    {:<<>>, line, Macro.unescape_tokens(pieces)}
  end

-  @doc """
+  @doc ~S"""
  Handles the sigil ~C. It simply returns a char list
  without escaping characters and without interpolations.

@@ -3352,15 +3395,15 @@ defmodule Kernel do
      iex> ~C(foo)
      'foo'

-      iex> ~C(f\#{o}o)
-      'f\\\#{o}o'
+      iex> ~C(f#{o}o)
+      'f\#{o}o'

  """
  defmacro sigil_C({:<<>>, _line, [string]}, []) when is_binary(string) do
    String.to_char_list(string)
  end

-  @doc """
+  @doc ~S"""
  Handles the sigil ~c. It returns a char list as if it were a single
  quoted string, unescaping characters and replacing interpolations.

@@ -3369,9 +3412,12 @@ defmodule Kernel do
      iex> ~c(foo)
      'foo'

-      iex> ~c(f\#{:o}o)
+      iex> ~c(f#{:o}o)
      'foo'

+      iex> ~c(f\#{:o}o)
+      'f\#{:o}o'
+
  """

  # We can skip the runtime conversion if we are
@@ -3405,13 +3451,13 @@ defmodule Kernel do
    quote do: Regex.compile!(unquote(binary), unquote(:binary.list_to_bin(options)))
  end

-  @doc """
+  @doc ~S"""
  Handles the sigil ~R. It returns a Regex pattern without escaping
  nor interpreting interpolations.

  ## Examples

-      iex> Regex.match?(~R(f\#{1,3}o), "f\#o")
+      iex> Regex.match?(~R(f#{1,3}o), "f#o")
      true

  """
@@ -3420,7 +3466,7 @@ defmodule Kernel do
    Macro.escape(regex)
  end

-  @doc """
+  @doc ~S"""
  Handles the sigil ~w. It returns a list of "words" split by whitespace.

  ## Modifiers
@@ -3431,7 +3477,7 @@ defmodule Kernel do

  ## Examples

-      iex> ~w(foo \#{:bar} baz)
+      iex> ~w(foo #{:bar} baz)
      ["foo", "bar", "baz"]

      iex> ~w(--source test/enum_test.exs)
@@ -3451,7 +3497,7 @@ defmodule Kernel do
    split_words(binary, modifiers)
  end

-  @doc """
+  @doc ~S"""
  Handles the sigil ~W. It returns a list of "words" split by whitespace
  without escaping nor interpreting interpolations.

@@ -3463,8 +3509,8 @@ defmodule Kernel do

  ## Examples

-      iex> ~W(foo \#{bar} baz)
-      ["foo", "\\\#{bar}", "baz"]
+      iex> ~W(foo #{bar} baz)
+      ["foo", "\#{bar}", "baz"]

  """
  defmacro sigil_W({:<<>>, _line, [string]}, modifiers) when is_binary(string) do
@@ -3,7 +3,7 @@ defmodule Kernel.CLI do

  @blank_config %{commands: [], output: ".", compile: [],
                  halt: true, compiler_options: [], errors: [],
-                  verbose_compile: false}
+                  pa: [], pz: [], verbose_compile: false}

  @doc """
  This is the API invoked by Elixir boot process.
@@ -12,9 +12,10 @@ defmodule Kernel.CLI do
    argv = for arg <- argv, do: IO.chardata_to_string(arg)

    {config, argv} = parse_argv(argv)
+    :elixir_code_server.cast({:paths, config.pa, config.pz})
    System.argv(argv)

-    run fn ->
+    run fn _ ->
      errors = process_commands(config)

      if errors != [] do
@@ -33,37 +34,19 @@ defmodule Kernel.CLI do
  by escripts generated by Elixir.
  """
  def run(fun, halt \\ true) do
-    try do
-      fun.()
-      if halt do
-        at_exit(0)
-        System.halt(0)
-      end
-    catch
-      :exit, reason when is_integer(reason) ->
-        at_exit(reason)
-        System.halt(reason)
-      :exit, :normal ->
-        at_exit(0)
-        System.halt(0)
-      kind, reason ->
-        at_exit(1)
-        print_error(kind, reason, System.stacktrace)
-        System.halt(1)
+    res = exec_fun(fun, {:ok, 0})
+    if elem(res, 0) == :shutdown or halt do
+      {_, int} = at_exit(res)
+      System.halt(int)
    end
  end

-  @doc """
-  Parses ARGV returning the CLI config and trailing args.
-  """
+  @doc false
  def parse_argv(argv) do
    parse_argv(argv, @blank_config)
  end

-  @doc """
-  Process commands according to the parsed config from `parse_argv/1`.
-  Returns all errors.
-  """
+  @doc false
  def process_commands(config) do
    results = Enum.map(Enum.reverse(config.commands), &process_command(&1, config))
    errors  = for {:error, msg} <- results, do: msg
@@ -72,21 +55,48 @@ defmodule Kernel.CLI do

  ## Helpers

-  defp at_exit(status) do
-    hooks = :elixir_code_server.call(:flush_at_exit)
+  defp at_exit(res) do
+    hooks = :elixir_config.get_and_put(:at_exit, [])
+    res = Enum.reduce(hooks, res, &exec_fun/2)
+    if hooks == [], do: res, else: at_exit(res)
+  end

-    for hook <- hooks do
+  defp exec_fun(fun, res) when is_function(fun, 1) and is_tuple(res) do
+    parent = self()
+
+    {pid, ref} =
+      spawn_monitor fn ->
        try do
-        hook.(status)
+          fun.(elem(res, 1))
        catch
+          :exit, {:shutdown, int} when is_integer(int) ->
+            send parent, {self, {:shutdown, int}}
+            exit({:shutdown, int})
+          :exit, reason
+              when reason == :normal
+              when reason == :shutdown
+              when tuple_size(reason) == 2 and elem(reason, 0) == :shutdown ->
+            send parent, {self, {:shutdown, 0}}
+            exit(reason)
          kind, reason ->
-          print_error(kind, reason, System.stacktrace)
+            stack = System.stacktrace
+            print_error(kind, reason, stack)
+            send parent, {self, {:shutdown, 1}}
+            :erlang.raise(kind, reason, stack)
+        else
+          _ ->
+            send parent, {self, res}
        end
      end

-    # If an at_exit callback adds a
-    # new hook we need to invoke it.
-    unless hooks == [], do: at_exit(status)
+    receive do
+      {^pid, res} ->
+        :erlang.demonitor(ref, [:flush])
+        res
+      {:DOWN, ^ref, _, _, other} ->
+        print_error({:EXIT, pid}, other, [])
+        {:shutdown, 1}
+    end
  end

  defp shared_option?(list, config, callback) do
@@ -103,7 +113,8 @@ defmodule Kernel.CLI do
    IO.puts :stderr, Exception.format(kind, reason, prune_stacktrace(trace))
  end

-  @elixir_internals [:elixir_compiler, :elixir_module, :elixir_translator, :elixir_expand]
+  @elixir_internals [:elixir, :elixir_exp, :elixir_compiler, :elixir_module, :elixir_translator,
+                     :elixir_expand, :elixir_lexical]

  defp prune_stacktrace([{mod, _, _, _}|t]) when mod in @elixir_internals do
    prune_stacktrace(t)
@@ -129,13 +140,15 @@ defmodule Kernel.CLI do
  end

  defp parse_shared(["-pa", h|t], config) do
-    add_code_path(h, &Code.prepend_path/1)
-    parse_shared t, config
+    paths = expand_code_path(h)
+    Enum.each(paths, &:code.add_patha/1)
+    parse_shared t, %{config | pa: config.pa ++ paths}
  end

  defp parse_shared(["-pz", h|t], config) do
-    add_code_path(h, &Code.append_path/1)
-    parse_shared t, config
+    paths = expand_code_path(h)
+    Enum.each(paths, &:code.add_pathz/1)
+    parse_shared t, %{config | pz: config.pz ++ paths}
  end

  defp parse_shared(["--app", h|t], config) do
@@ -162,7 +175,7 @@ defmodule Kernel.CLI do
    parse_shared t, config
  end

-  defp parse_shared([erl|t], config) when erl in ["--detached", "--hidden"] do
+  defp parse_shared([erl|t], config) when erl in ["--detached", "--hidden", "--werl"] do
    parse_shared t, config
  end

@@ -170,12 +183,11 @@ defmodule Kernel.CLI do
    {list, config}
  end

-
-  defp add_code_path(path, fun) do
+  defp expand_code_path(path) do
    path = Path.expand(path)
    case Path.wildcard(path) do
-      []   -> fun.(path)
-      list -> Enum.each(list, fun)
+      []   -> [to_char_list(path)]
+      list -> Enum.map(list, &to_char_list/1)
    end
  end

@@ -352,7 +364,8 @@ defmodule Kernel.CLI do
  end

  defp process_command({:compile, patterns}, config) do
-    :filelib.ensure_dir(:filename.join(config.output, "."))
+    # If ensuring the dir returns an error no files will be found.
+    _ = :filelib.ensure_dir(:filename.join(config.output, "."))

    case filter_multiple_patterns(patterns) do
      {:ok, []} ->
@@ -396,7 +409,7 @@ defmodule Kernel.CLI do
  end

  defp wrapper(fun) do
-    fun.()
+    _ = fun.()
    :ok
  end

@@ -407,8 +420,8 @@ defmodule Kernel.CLI do
      # the actual Elixir executable.
      case :os.type() do
        {:win32, _} ->
-          exec = Path.rootname(exec)
-          if File.regular?(exec), do: exec
+          base = Path.rootname(exec)
+          if File.regular?(base), do: base, else: exec
        _ ->
          exec
      end
@@ -25,11 +25,11 @@ defmodule Kernel.ErrorHandler do

  defp ensure_loaded(module) do
    case Code.ensure_loaded(module) do
-      {:module, _} -> []
+      {:module, _} -> :ok
      {:error, _} ->
        parent = :erlang.get(:elixir_compiler_pid)
        ref    = :erlang.make_ref
-        send parent, {:waiting, module, self(), ref, module}
+        send parent, {:waiting, :module, self(), ref, module}
        :erlang.garbage_collect(self)
        receive do
          {^ref, :ready}   -> :ok
@@ -18,20 +18,22 @@ defmodule Kernel.LexicalTracker do
  Returns all remotes linked to in this lexical scope.
  """
  def remotes(arg) do
-    # If the module is compiled from a function, its lexical
-    # scope may be long gone, so it has no associated PID.
-    if pid = to_pid(arg) do
-      ets = :gen_server.call(pid, :ets, @timeout)
+    ets = :gen_server.call(to_pid(arg), :ets, @timeout)
    :ets.match(ets, {:"$1", :_, :_}) |> List.flatten
-    else
-      []
  end
+
+  @doc """
+  Gets the destination the lexical scope is meant to
+  compile to.
+  """
+  def dest(arg) do
+    :gen_server.call(to_pid(arg), :dest, @timeout)
  end

  defp to_pid(pid) when is_pid(pid),  do: pid
  defp to_pid(mod) when is_atom(mod) do
    table = :elixir_module.data_table(mod)
-    [{_, val}] = :ets.lookup(table, :__lexical_tracker)
+    [{_, val}] = :ets.lookup(table, {:elixir, :lexical_tracker})
    val
  end

@@ -39,9 +41,8 @@ defmodule Kernel.LexicalTracker do

  # Starts the tracker and returns its pid.
  @doc false
-  def start_link do
-    {:ok, pid} = :gen_server.start_link(__MODULE__, [], [])
-    pid
+  def start_link(dest) do
+    :gen_server.start_link(__MODULE__, dest, [])
  end

  @doc false
@@ -96,62 +97,69 @@ defmodule Kernel.LexicalTracker do

  # Callbacks

-
-  def init([]) do
-    {:ok, :ets.new(:lexical, [:protected])}
+  def init(dest) do
+    {:ok, {:ets.new(:lexical, [:protected]), dest}}
  end

-  def handle_call(:ets, _from, d) do
-    {:reply, d, d}
+  @doc false
+  def handle_call(:ets, _from, {d, dest}) do
+    {:reply, d, {d, dest}}
  end

-  def handle_call(request, _from, d) do
-    {:stop, {:bad_call, request}, d}
+  def handle_call(:dest, _from, {d, dest}) do
+    {:reply, dest, {d, dest}}
  end

-  def handle_cast({:remote_dispatch, module}, d) do
+  def handle_call(request, _from, {d, dest}) do
+    {:stop, {:bad_call, request}, {d, dest}}
+  end
+
+  def handle_cast({:remote_dispatch, module}, {d, dest}) do
    add_module(d, module)
-    {:noreply, d}
+    {:noreply, {d, dest}}
  end

-  def handle_cast({:import_dispatch, module}, d) do
+  def handle_cast({:import_dispatch, module}, {d, dest}) do
    add_dispatch(d, module, @import)
-    {:noreply, d}
+    {:noreply, {d, dest}}
  end

-  def handle_cast({:alias_dispatch, module}, d) do
+  def handle_cast({:alias_dispatch, module}, {d, dest}) do
    add_dispatch(d, module, @alias)
-    {:noreply, d}
+    {:noreply, {d, dest}}
  end

-  def handle_cast({:add_import, module, line, warn}, d) do
+  def handle_cast({:add_import, module, line, warn}, {d, dest}) do
    add_directive(d, module, line, warn, @import)
-    {:noreply, d}
+    {:noreply, {d, dest}}
  end

-  def handle_cast({:add_alias, module, line, warn}, d) do
+  def handle_cast({:add_alias, module, line, warn}, {d, dest}) do
    add_directive(d, module, line, warn, @alias)
-    {:noreply, d}
+    {:noreply, {d, dest}}
  end

-  def handle_cast(:stop, d) do
-    {:stop, :normal, d}
+  def handle_cast(:stop, {d, dest}) do
+    {:stop, :normal, {d, dest}}
  end

-  def handle_cast(msg, d) do
-    {:stop, {:bad_cast, msg}, d}
+  def handle_cast(msg, {d, dest}) do
+    {:stop, {:bad_cast, msg}, {d, dest}}
  end

-  def handle_info(_msg, d) do
-    {:noreply, d}
+  @doc false
+  def handle_info(_msg, {d, dest}) do
+    {:noreply, {d, dest}}
  end

-  def terminate(_reason, _d) do
+  @doc false
+  def terminate(_reason, _state) do
    :ok
  end

-  def code_change(_old, d, _extra) do
-    {:ok, d}
+  @doc false
+  def code_change(_old, state, _extra) do
+    {:ok, state}
  end

  # Callbacks helpers
@@ -15,7 +15,7 @@ defmodule Kernel.ParallelCompiler do
  is set to `true` and there is a warning, this function will fail
  with an exception.

-  This function receives a set of callbacks as options:
+  This function accepts the following options:

    * `:each_file` - for each file compiled, invokes the callback passing the
      file
@@ -23,57 +23,61 @@ defmodule Kernel.ParallelCompiler do
    * `:each_module` - for each module compiled, invokes the callback passing
      the file, module and the module bytecode

-  The compiler doesn't care about the return values of the callbacks.
+    * `:dest` - the destination directory for the beam files. When using `files/2`,
+      this information is only used to properly annotate the beam files before
+      they are loaded into memory. If you want a file to actually be writen to
+      `dest`, use `files_to_path/3` instead.
+
  Returns the modules generated by each compiled file.
  """
-  def files(files, callbacks \\ [])
+  def files(files, options \\ [])

-  def files(files, callbacks) when is_list(callbacks) do
-    spawn_compilers(files, nil, callbacks)
+  def files(files, options) when is_list(options) do
+    spawn_compilers(files, nil, options)
  end

  @doc """
  Compiles the given files to the given path.
  Read `files/2` for more information.
  """
-  def files_to_path(files, path, callbacks \\ [])
+  def files_to_path(files, path, options \\ [])

-  def files_to_path(files, path, callbacks) when is_binary(path) and is_list(callbacks) do
-    spawn_compilers(files, path, callbacks)
+  def files_to_path(files, path, options) when is_binary(path) and is_list(options) do
+    spawn_compilers(files, path, options)
  end

-  defp spawn_compilers(files, path, callbacks) do
-    Code.ensure_loaded(Kernel.ErrorHandler)
+  defp spawn_compilers(files, path, options) do
+    true = Code.ensure_loaded?(Kernel.ErrorHandler)
    compiler_pid = self()
    :elixir_code_server.cast({:reset_warnings, compiler_pid})
    schedulers = max(:erlang.system_info(:schedulers_online), 2)

-    result = spawn_compilers(files, files, path, callbacks, [], [], schedulers, [])
+    result = spawn_compilers(files, files, path, options, [], [], schedulers, [])

    # In case --warning-as-errors is enabled and there was a warning,
    # compilation status will be set to error and we fail with CompileError
    case :elixir_code_server.call({:compilation_status, compiler_pid}) do
      :ok    -> result
-      :error -> exit(1)
+      :error -> exit({:shutdown, 1})
    end
  end

  # We already have 4 currently running, don't spawn new ones
-  defp spawn_compilers(entries, original, output, callbacks, waiting, queued, schedulers, result) when
+  defp spawn_compilers(entries, original, output, options, waiting, queued, schedulers, result) when
      length(queued) - length(waiting) >= schedulers do
-    wait_for_messages(entries, original, output, callbacks, waiting, queued, schedulers, result)
+    wait_for_messages(entries, original, output, options, waiting, queued, schedulers, result)
  end

  # Release waiting processes
-  defp spawn_compilers([h|t], original, output, callbacks, waiting, queued, schedulers, result) when is_pid(h) do
+  defp spawn_compilers([h|t], original, output, options, waiting, queued, schedulers, result) when is_pid(h) do
    {_kind, ^h, ref, _module} = List.keyfind(waiting, h, 1)
    send h, {ref, :ready}
    waiting = List.keydelete(waiting, h, 1)
-    spawn_compilers(t, original, output, callbacks, waiting, queued, schedulers, result)
+    spawn_compilers(t, original, output, options, waiting, queued, schedulers, result)
  end

  # Spawn a compiler for each file in the list until we reach the limit
-  defp spawn_compilers([h|t], original, output, callbacks, waiting, queued, schedulers, result) do
+  defp spawn_compilers([h|t], original, output, options, waiting, queued, schedulers, result) do
    parent = self()

    {pid, ref} =
@@ -87,43 +91,43 @@ defmodule Kernel.ParallelCompiler do
        :erlang.process_flag(:error_handler, Kernel.ErrorHandler)

        exit(try do
-          if output do
+          _ = if output do
            :elixir_compiler.file_to_path(h, output)
          else
-            :elixir_compiler.file(h)
+            :elixir_compiler.file(h, Keyword.get(options, :dest))
          end
-          {:compiled, h}
+          {:shutdown, h}
        catch
          kind, reason ->
            {:failure, kind, reason, System.stacktrace}
        end)
      end

-    spawn_compilers(t, original, output, callbacks, waiting,
+    spawn_compilers(t, original, output, options, waiting,
                    [{pid, ref, h}|queued], schedulers, result)
  end

  # No more files, nothing waiting, queue is empty, we are done
-  defp spawn_compilers([], _original, _output, _callbacks, [], [], _schedulers, result) do
+  defp spawn_compilers([], _original, _output, _options, [], [], _schedulers, result) do
    for {:module, mod} <- result, do: mod
  end

  # Queued x, waiting for x: POSSIBLE ERROR! Release processes so we get the failures
-  defp spawn_compilers([], original, output, callbacks, waiting, queued, schedulers, result) when length(waiting) == length(queued) do
+  defp spawn_compilers([], original, output, options, waiting, queued, schedulers, result) when length(waiting) == length(queued) do
    Enum.each queued, fn {child, _, _} ->
      {_kind, ^child, ref, _module} = List.keyfind(waiting, child, 1)
      send child, {ref, :release}
    end
-    wait_for_messages([], original, output, callbacks, waiting, queued, schedulers, result)
+    wait_for_messages([], original, output, options, waiting, queued, schedulers, result)
  end

  # No more files, but queue and waiting are not full or do not match
-  defp spawn_compilers([], original, output, callbacks, waiting, queued, schedulers, result) do
-    wait_for_messages([], original, output, callbacks, waiting, queued, schedulers, result)
+  defp spawn_compilers([], original, output, options, waiting, queued, schedulers, result) do
+    wait_for_messages([], original, output, options, waiting, queued, schedulers, result)
  end

  # Wait for messages from child processes
-  defp wait_for_messages(entries, original, output, callbacks, waiting, queued, schedulers, result) do
+  defp wait_for_messages(entries, original, output, options, waiting, queued, schedulers, result) do
    receive do
      {:struct_available, module} ->
        available = for {:struct, pid, _, waiting_module} <- waiting,
@@ -131,11 +135,11 @@ defmodule Kernel.ParallelCompiler do
                        not pid in entries,
                        do: pid

-        spawn_compilers(available ++ entries, original, output, callbacks,
+        spawn_compilers(available ++ entries, original, output, options,
                        waiting, queued, schedulers, [{:struct, module}|result])

      {:module_available, child, ref, file, module, binary} ->
-        if callback = Keyword.get(callbacks, :each_module) do
+        if callback = Keyword.get(options, :each_module) do
          callback.(file, module, binary)
        end

@@ -147,7 +151,7 @@ defmodule Kernel.ParallelCompiler do
                        not pid in entries,
                        do: pid

-        spawn_compilers(available ++ entries, original, output, callbacks,
+        spawn_compilers(available ++ entries, original, output, options,
                        waiting, queued, schedulers, [{:module, module}|result])

      {:waiting, kind, child, ref, on} ->
@@ -160,10 +164,10 @@ defmodule Kernel.ParallelCompiler do
          waiting = [{kind, child, ref, on}|waiting]
        end

-        spawn_compilers(entries, original, output, callbacks, waiting, queued, schedulers, result)
+        spawn_compilers(entries, original, output, options, waiting, queued, schedulers, result)

-      {:DOWN, _down_ref, :process, down_pid, {:compiled, file}} ->
-        if callback = Keyword.get(callbacks, :each_file) do
+      {:DOWN, _down_ref, :process, down_pid, {:shutdown, file}} ->
+        if callback = Keyword.get(options, :each_file) do
          callback.(file)
        end

@@ -172,21 +176,27 @@ defmodule Kernel.ParallelCompiler do
        new_entries = List.delete(entries, down_pid)
        new_queued  = List.keydelete(queued, down_pid, 0)
        new_waiting = List.keydelete(waiting, down_pid, 1)
-        spawn_compilers(new_entries, original, output, callbacks, new_waiting, new_queued, schedulers, result)
+        spawn_compilers(new_entries, original, output, options, new_waiting, new_queued, schedulers, result)

      {:DOWN, down_ref, :process, _down_pid, reason} ->
        handle_failure(down_ref, reason, entries, waiting, queued)
-        wait_for_messages(entries, original, output, callbacks, waiting, queued, schedulers, result)
+        wait_for_messages(entries, original, output, options, waiting, queued, schedulers, result)
    end
  end

  defp handle_failure(ref, reason, entries, waiting, queued) do
    if file = find_failure(ref, queued) do
      print_failure(file, reason)
+
      if all_missing?(entries, waiting, queued) do
        collect_failures(queued, length(queued) - 1)
      end
-      exit(1)
+
+      Enum.each queued, fn {child, _, _} ->
+        Process.exit(child, :kill)
+      end
+
+      exit({:shutdown, 1})
    end
  end

@@ -197,7 +207,7 @@ defmodule Kernel.ParallelCompiler do
    end
  end

-  defp print_failure(_file, {:compiled, _}) do
+  defp print_failure(_file, {:shutdown, _}) do
    :ok
  end

@@ -211,7 +221,8 @@ defmodule Kernel.ParallelCompiler do
    IO.puts Exception.format(:exit, reason, [])
  end

-  @elixir_internals [:elixir_compiler, :elixir_module, :elixir_translator, :elixir_expand]
+  @elixir_internals [:elixir, :elixir_exp, :elixir_compiler, :elixir_module, :elixir_translator,
+                     :elixir_expand, :elixir_lexical]

  defp prune_stacktrace([{mod, _, _, _}|t]) when mod in @elixir_internals do
    prune_stacktrace(t)
@@ -114,7 +114,7 @@ defmodule Kernel.SpecialForms do

      defmodule User do
        def __struct__ do
-          %{name: "josé", age: 27}
+          %{name: "john", age: 27}
        end
      end

@@ -122,7 +122,7 @@ defmodule Kernel.SpecialForms do
  `Kernel.defstruct/1` macro:

      defmodule User do
-        defstruct name: "josé", age: 27
+        defstruct name: "john", age: 27
      end

  Now a struct can be created as follows:
@@ -132,13 +132,13 @@ defmodule Kernel.SpecialForms do
  Underneath a struct is just a map with a `__struct__` field
  pointing to the `User` module:

-      %User{} == %{__struct__: User, name: "josé", age: 27}
+      %User{} == %{__struct__: User, name: "john", age: 27}

  A struct also validates that the given keys are part of the defined
  struct. The example below will fail because there is no key
  `:full_name` in the `User` struct:

-      %User{full_name: "José Valim"}
+      %User{full_name: "john doe"}

  Note that a struct specifies a minimum set of keys required
  for operations. Other keys can be added to structs via the
@@ -172,10 +172,22 @@ defmodule Kernel.SpecialForms do
      iex> << 1, 2, 3 >>
      << 1, 2, 3 >>

-  ## Bitstring types
+  ## Types

-  A bitstring is made of many segments. Each segment has a
-  type, which defaults to integer:
+  A bitstring is made of many segments and each segment has a
+  type. There are 9 types used in bitstrings:
+
+    - `integer`
+    - `float`
+    - `bits` (alias for bitstring)
+    - `bitstring`
+    - `binary`
+    - `bytes` (alias for binary)
+    - `utf8`
+    - `utf16`
+    - `utf32`
+
+  When no type is specified, the default is `integer`:

      iex> <<1, 2, 3>>
      <<1, 2, 3>>
@@ -186,14 +198,7 @@ defmodule Kernel.SpecialForms do
      iex> <<0, "foo">>
      <<0, 102, 111, 111>>

-  Any other type needs to be explicitly tagged. For example,
-  in order to store a float type in the binary, one has to do:
-
-      iex> <<3.14 :: float>>
-      <<64, 9, 30, 184, 81, 235, 133, 31>>
-
-  This also means that variables need to be explicitly tagged,
-  otherwise Elixir defaults to integer:
+  Variables or any other type need to be explicitly tagged:

      iex> rest = "oo"
      iex> <<102, rest>>
@@ -201,100 +206,161 @@ defmodule Kernel.SpecialForms do

  We can solve this by explicitly tagging it as a binary:

-      <<102, rest :: binary>>
-
-  The type can be integer, float, bitstring/bits, binary/bytes,
-  utf8, utf16 or utf32, e.g.:
-
-      <<102 :: float, rest :: binary>>
-
-  An integer can be any arbitrary precision integer. A float is an
-  IEEE 754 binary32 or binary64 floating point number. A bitstring
-  is an arbitrary series of bits. A binary is a special case of
-  bitstring that has a total size divisible by 8.
+      iex> rest = "oo"
+      iex> <<102, rest :: binary>>
+      "foo"

  The utf8, utf16, and utf32 types are for unicode codepoints. They
  can also be applied to literal strings and char lists:

      iex> <<"foo" :: utf16>>
      <<0, 102, 0, 111, 0, 111>>
+      iex> <<"foo" :: utf32>>
+      <<0, 0, 0, 102, 0, 0, 0, 111, 0, 0, 0, 111>>

-  The bits type is an alias for bitstring. The bytes type is an
-  alias for binary.
+  ## Options

-  The signedness can also be given as signed or unsigned. The
-  signedness only matters for matching and relevant only for
-  integers. If unspecified, it defaults to unsigned. Example:
+  Many options can be given by using `-` as separator. Order is
+  arbitrary, so the following are all equivalent:
+
+      <<102 :: integer-native, rest :: binary>>
+      <<102 :: native-integer, rest :: binary>>
+      <<102 :: unsigned-big-integer, rest :: binary>>
+      <<102 :: unsigned-big-integer-size(8), rest :: binary>>
+      <<102 :: unsigned-big-integer-8, rest :: binary>>
+      <<102 :: 8-integer-big-unsigned, rest :: binary>>
+      <<102, rest :: binary>>
+
+  ### Unit and Size
+
+  The length of the match is equal to the `unit` (a number of bits) times the
+  `size` (the number of repeated segnments of length `unit`).
+
+  Type      | Default Unit
+  --------- | ------------
+  `integer` | 1 bit
+  `float`   | 1 bit
+  `binary`  | 8 bits
+
+  Sizes for types are a bit more nuanced. The default size for integers is 8.
+
+  For floats, it is 64. For floats, `size * unit` must result in 32 or 64,
+  corresponding to [IEEE 754](http://en.wikipedia.org/wiki/IEEE_floating_point)
+  binary32 and binary64, respectively.
+
+  For binaries, the default is the size of the binary. Only the last binary in a
+  match can use the default size. All others must have their size specified
+  explicitly, even if the match is unambiguous. For example:
+
+      iex> <<name::binary-size(5), " the ", species::binary>> = <<"Frank the Walrus">>
+      "Frank the Walrus"
+      iex> {name, species}
+      {"Frank", "Walrus"}
+
+  Failing to specify the size for the non-last causes compilation to fail:
+
+      <<name::binary, " the ", species::binary>> = <<"Frank the Walrus">>
+      ** (CompileError): a binary field without size is only allowed at the end of a binary pattern
+
+  #### Shortcut Syntax
+
+  Size and unit can also be specified using a syntax shortcut
+  when passing integer values:
+
+      iex> x = 1
+      iex> << x :: 8 >> == << x :: size(8) >>
+      true
+      iex> << x :: 8 * 4 >> == << x :: size(8)-unit(4) >>
+      true
+
+  This syntax reflects the fact the effective size is given by
+  multiplying the size by the unit.
+
+  ### Modifiers
+
+  Some types have associated modifiers to clear up ambiguity in byte
+  representation.
+
+  Modifier             | Relevant Type(s)
+  -------------------- | ----------------
+  `signed`             | `integer`
+  `unsigned` (default) | `integer`
+  `little`             | `integer`, `utf16`, `utf32`
+  `big` (default)      | `integer`, `utf16`, `utf32`
+  `native`             | `integer`, `utf16`, `utf32`
+
+  ### Sign
+
+  Integers can be `signed` or `unsigned`, defaulting to `unsigned`.
+
+      iex> <<int::integer>> =  <<-100>>
+      <<156>>
+      iex> int
+      156
+      iex> <<int::integer-signed>> =  <<-100>>
+      <<156>>
+      iex> int
+      -100
+
+  `signed` and `unsigned` are only used for matching binaries (see below) and
+  are only used for integers.

      iex> <<-100 :: signed, _rest :: binary>> = <<-100, "foo">>
      <<156, 102, 111, 111>>

-  This match would have failed if we did not specify that the
-  value -100 is signed. If we're matching into a variable instead
-  of a value, the signedness won't be checked; rather, the number
-  will simply be interpreted as having the given (or implied)
-  signedness, e.g.:
+  ### Endianness

-      iex> <<val, _rest :: binary>> = <<-100, "foo">>
-      iex> val
-      156
+  Elixir has three options for endianness: `big`, `little`, and `native`.
+  The default is `big`. `native` is determined by the VM at startup.

-  Here, `val` is interpreted as unsigned.
+      iex> <<number::little-integer-size(16)>> = <<0, 1>>
+      <<0, 1>>
+      iex> number
+      256
+      iex> <<number::big-integer-size(16)>> = <<0, 1>>
+      <<0, 1>>
+      iex> number
+      1
+      iex> <<number::native-integer-size(16)>> = <<0, 1>>
+      <<0, 1>>
+      iex> number
+      256

-  The endianness of a segment can be big, little or native (the
-  latter meaning it will be resolved at VM load time). Passing
-  many options can be done by giving a list:
+  ## Binary/Bitstring Matching

-      <<102 :: [integer, native], rest :: binary>>
+  Binary matching is a powerful feature in Elixir that is useful for extracting
+  information from binaries as well as pattern matching.

-  Or:
+  Binary matching can be used by itself to extract information from binaries:

-      <<102 :: [unsigned, big, integer], rest :: binary>>
+      iex> <<"Hello, ", place::binary>> = "Hello, World"
+      "Hello, World"
+      iex> place
+      "World"

-  And so on.
+  Or as a part of function definitions to pattern match:

-  Endianness only makes sense for integers and some UTF code
-  point types (utf16 and utf32).
+      defmodule ImageTyper
+        @png_signature <<137::size(8), 80::size(8), 78::size(8), 71::size(8),
+                      13::size(8), 10::size(8), 26::size(8), 10::size(8)>>
+        @jpg_signature <<255::size(8), 216::size(8)>>

-  Finally, we can also specify size and unit for each segment. The
-  unit is multiplied by the size to give the effective size of
-  the segment in bits. The default unit for integers, floats,
-  and bitstrings is 1. For binaries, it is 8.
+        def type(<<@png_signature, rest::binary>>), do: :png
+        def type(<<@jpg_signature, rest::binary>>), do: :jpg
+        def type(_), do :unknown
+      end

-  Since integers are default, the default unit is 1. The example below
-  matches because the string "foo" takes 24 bits and we match it
-  against a segment of 24 bits, 8 of which are taken by the integer
-  102 and the remaining 16 bits are specified on the rest.
+  ### Performance & Optimizations

-      iex> <<102, _rest :: size(16)>> = "foo"
-      "foo"
+  The Erlang compiler can provide a number of optimizations on binary creation
+  and matching. To see optimization output, set the `bin_opt_info` compiler
+  option:

-  We can also match by specifying size and unit explicitly:
+      ERL_COMPILER_OPTIONS=bin_opt_info mix compile

-      iex> <<102, _rest :: [size(2), unit(8)]>> = "foo"
-      "foo"
-
-  However, if we expect a size of 32, it won't match:
-
-      iex> <<102, _rest :: size(32)>> = "foo"
-      ** (MatchError) no match of right hand side value: "foo"
-
-  Size and unit are not applicable to utf8, utf16, and utf32.
-
-  The default size for integers is 8. For floats, it is 64. For
-  binaries, it is the size of the binary. Only the last binary
-  in a binary match can use the default size (all others must
-  have their size specified explicitly).
-
-  Size can also be specified using a syntax shortcut. Instead of
-  writing `size(8)`, one can write just `8` and it will be interpreted
-  as `size(8)`
-
-      iex> << 1 :: 3 >> == << 1 :: size(3) >>
-      true
-
-  For floats, `size * unit` must result in 32 or 64, corresponding
-  to binary32 and binary64, respectively.
+  To learn more about specific optimizations and performance considerations,
+  check out
+  [Erlang's Efficiency Guide on handling binaries](http://www.erlang.org/doc/efficiency_guide/binaryhandling.html).
  """
  defmacro unquote(:<<>>)(args)

@@ -340,28 +406,9 @@ defmodule Kernel.SpecialForms do

  Note that `Kernel."HELLO"` will be treated as a remote call and not an alias.
  This choice was done so every time single- or double-quotes are used, we have
-  a remote call irregardless of the quote contents. This decision is also reflected
+  a remote call regardless of the quote contents. This decision is also reflected
  in the quoted expressions discussed below.

-  ## Runtime (dynamic) behaviour
-
-  The result returned by `.` is always specified by the right-side:
-
-      iex> x = String
-      iex> x.downcase("FOO")
-      "foo"
-      iex> x.Sample
-      String.Sample
-
-  In case the right-side is also dynamic, `.`'s behaviour can be reproduced
-  at runtime via `apply/3` and `Module.concat/2`:
-
-      iex> apply(:erlang, :+, [1,2])
-      3
-
-      iex> Module.concat(Kernel, Sample)
-      Kernel.Sample
-
  ## Quoted expression

  When `.` is used, the quoted expression may take two distinct
@@ -1109,7 +1156,7 @@ defmodule Kernel.SpecialForms do

  ## Examples

-  Imagine the situation you have a variable `name` and
+  Imagine the situation you have a variable `value` and
  you want to inject it inside some quote. The first attempt
  would be:

@@ -1171,10 +1218,10 @@ defmodule Kernel.SpecialForms do
  Note generators can also be used to filter as it removes any value
  that doesn't match the left side of `<-`:

-      iex> for {:user, name} <- [user: "jose", admin: "john", user: "eric"] do
+      iex> for {:user, name} <- [user: "john", admin: "john", user: "meg"] do
      ...>   String.upcase(name)
      ...> end
-      ["JOSE", "ERIC"]
+      ["JOHN", "MEG"]

  Bitstring generators are also supported and are very useful when you
  need to organize bitstring streams:
@@ -1324,22 +1371,13 @@ defmodule Kernel.SpecialForms do

  On the other hand, aliases holds some properties:

-    1. The head element of aliases can be any term.
+    1. The head element of aliases can be any term that must expand to
+       an atom at compilation time.

    2. The tail elements of aliases are guaranteed to always be atoms.

    3. When the head element of aliases is the atom `:Elixir`, no expansion happen.

-    4. When the head element of aliases is not an atom, it is expanded at runtime:
-
-           quote do: some_var.Foo
-           {:__aliases__, [], [{:some_var, [], Elixir}, :Foo]}
-
-       Since `some_var` is not available at compilation time, the compiler
-       expands such expression to:
-
-           Module.concat [some_var, Foo]
-
  """
  defmacro __aliases__(args)

@@ -1513,9 +1551,9 @@ defmodule Kernel.SpecialForms do
  The catch clause can be used to catch throws values and exits.

      try do
-        exit(1)
+        exit(:shutdown)
      catch
-        :exit, 1 -> IO.puts "Exited with 1"
+        :exit, :shutdown -> IO.puts "Exited with shutdown reason"
      end

      try do
@@ -1,5 +1,5 @@
 defmodule Kernel.Typespec do
-  @moduledoc """
+  @moduledoc ~S"""
  Provides macros and functions for working with typespecs.

  Elixir comes with a notation for declaring types and specifications. Elixir is
@@ -38,6 +38,7 @@ defmodule Kernel.Typespec do
            | Fun
            | Integer
            | List
+            | Map
            | Tuple
            | Union
            | UserDefined # Described in section "Defining a type"
@@ -65,16 +66,33 @@ defmodule Kernel.Typespec do
            | nonempty_list(Type)               # proper non-empty list
            | []                                # empty list
            | [Type]                            # shorthand for list(Type)
+            | [...]                             # shorthand for nonempty_list()
            | [Type, ...]                       # shorthand for nonempty_list(Type)
+            | [Keyword]
+
+      Map :: map()            # map of any size
+           | %{}              # map of any size
+           | %Struct{}        # struct (see defstruct/1)
+           | %Struct{Keyword}
+           | %{Keyword}
+           | %{Pairs}

      Tuple :: tuple                 # a tuple of any size
             | {}                    # empty tuple
             | {TList}
+             | record(Atom)          # record (see Record)
+             | record(Atom, Keyword)
+
+      Keyword :: ElixirAtom: Type
+               | ElixirAtom: Type, Keyword
+
+      Pairs :: Type => Type
+             | Type => Type, Pairs

      TList :: Type
             | Type, TList

-      Union :: Type1 | Type2
+      Union :: Type | Type

  ### Bit strings

@@ -109,23 +127,25 @@ defmodule Kernel.Typespec do
  `term`                | `any`
  `binary`              | `<< _ :: _ * 8 >>`
  `bitstring`           | `<< _ :: _ * 1 >>`
-      `boolean`             | `false` &#124; `true`
+  `boolean`             | `false` \| `true`
  `byte`                | `0..255`
-      `char`                | `0..0xffff`
-      `number`              | `integer` &#124; `float`
+  `char`                | `0..0x10ffff`
+  `number`              | `integer` \| `float`
+  `char_list`           | `[char]`
  `list`                | `[any]`
  `maybe_improper_list` | `maybe_improper_list(any, any)`
  `nonempty_list`       | `nonempty_list(any)`
-      `iodata`              | `iolist` &#124; `binary`
-      `iolist`              | `maybe_improper_list(byte` &#124; `binary` &#124; `iolist, binary` &#124; `[])`
-      `module`              | `atom`
+  `iodata`              | `iolist` \| `binary`
+  `iolist`              | `maybe_improper_list(byte` \| `binary` \| `iolist, binary` \| `[])`
+  `module`              | `atom` \| `tuple`
  `mfa`                 | `{atom, atom, arity}`
  `arity`               | `0..255`
  `node`                | `atom`
-      `timeout`             | `:infinity` &#124; `non_neg_integer`
+  `timeout`             | `:infinity` \| `non_neg_integer`
  `no_return`           | `none`
  `fun`                 | `(... -> any)`

+
  Some built-in types cannot be expressed with valid syntax according to the
  language defined above.

@@ -488,9 +508,9 @@ defmodule Kernel.Typespec do
    do: type_to_signature(other)

  @doc false
-  def type_to_signature({:::, _, [{name, _, nil}, _]}),
+  def type_to_signature({:::, _, [{name, _, context}, _]}) when is_atom(name) and is_atom(context),
    do: {name, 0}
-  def type_to_signature({:::, _, [{name, _, args}, _]}),
+  def type_to_signature({:::, _, [{name, _, args}, _]}) when is_atom(name),
    do: {name, length(args)}

  ## Macro callbacks
@@ -536,7 +556,7 @@ defmodule Kernel.Typespec do

    if not export and doc do
      :elixir_errors.warn(caller.line, caller.file, "type #{name}/#{arity} is private, " <>
-                          "@typedoc's are always discarded for private types\n")
+                          "@typedoc's are always discarded for private types")
    end

    {{kind, {name, arity}, type}, caller.line, export, doc}
@@ -624,6 +644,10 @@ defmodule Kernel.Typespec do
    []
  end

+  defp typespec_to_ast({:user_type, line, name, args}) do
+    typespec_to_ast({:type, line, name, args})
+  end
+
  defp typespec_to_ast({:type, line, :tuple, :any}) do
    {:tuple, [line: line], []}
  end
@@ -640,12 +664,29 @@ defmodule Kernel.Typespec do
    end
  end

-  defp typespec_to_ast({:type, _line, :list, args}) do
-    for arg <- args, do: typespec_to_ast(arg)
+  defp typespec_to_ast({:type, line, :list, []}) do
+    {:list, [line: line], []}
+  end
+
+  defp typespec_to_ast({:type, _line, :list, [arg]}) do
+    [typespec_to_ast(arg)]
+  end
+
+  defp typespec_to_ast({:type, line, :nonempty_list, []}) do
+    [{:..., [line: line], nil}]
+  end
+
+  defp typespec_to_ast({:type, line, :nonempty_list, [arg]}) do
+    [typespec_to_ast(arg), {:..., [line: line], nil}]
  end

  defp typespec_to_ast({:type, line, :map, fields}) do
-    fields = Enum.map fields, fn {:type, _, :map_field_assoc, k, v} ->
+    fields = Enum.map fields, fn
+      # OTP 18
+      {:type, _, :map_field_assoc, [k, v]} ->
+        {typespec_to_ast(k), typespec_to_ast(v)}
+      # OTP 17
+      {:type, _, :map_field_assoc, k, v} ->
        {typespec_to_ast(k), typespec_to_ast(v)}
    end

@@ -690,7 +731,11 @@ defmodule Kernel.Typespec do
  end

  defp typespec_to_ast({:type, line, :range, [left, right]}) do
-    {:"..", [line: line], [typespec_to_ast(left), typespec_to_ast(right)]}
+    {:.., [line: line], [typespec_to_ast(left), typespec_to_ast(right)]}
+  end
+
+  defp typespec_to_ast({:type, _line, nil, []}) do
+    []
  end

  defp typespec_to_ast({:type, line, name, args}) do
@@ -747,9 +792,9 @@ defmodule Kernel.Typespec do

  defp erl_to_ex_var(var) do
    case Atom.to_string(var) do
-      <<"_", c :: [binary, size(1)], rest :: binary>> ->
+      <<"_", c :: binary-size(1), rest :: binary>> ->
        String.to_atom("_#{String.downcase(c)}#{rest}")
-      <<c :: [binary, size(1)], rest :: binary>> ->
+      <<c :: binary-size(1), rest :: binary>> ->
        String.to_atom("#{String.downcase(c)}#{rest}")
    end
  end
@@ -785,19 +830,79 @@ defmodule Kernel.Typespec do

  ## Handle maps and structs
  defp typespec({:%{}, meta, fields}, vars, caller) do
-    fields = :lists.map(fn {k, v} ->
+    fields =
+      if :erlang.system_info(:otp_release) >= '18' do
+        :lists.map(fn {k, v} ->
+          {:type, line(meta), :map_field_assoc, [typespec(k, vars, caller), typespec(v, vars, caller)]}
+        end, fields)
+      else
+        :lists.map(fn {k, v} ->
          {:type, line(meta), :map_field_assoc, typespec(k, vars, caller), typespec(v, vars, caller)}
        end, fields)
+      end
+
    {:type, line(meta), :map, fields}
  end

  defp typespec({:%, _, [name, {:%{}, meta, fields}]}, vars, caller) do
-    typespec({:%{}, meta, [{:__struct__, name}|fields]}, vars, caller)
+    module = Macro.expand(name, caller)
+
+    struct =
+      if module == caller.module do
+        Module.get_attribute(module, :struct) ||
+          compile_error(caller, "struct is not defined for #{Macro.to_string(name)}")
+      else
+        module.__struct__
+      end
+
+    struct =
+      :lists.map(fn {field, _} ->
+        {field, quote do: term()}
+      end, Map.to_list(struct))
+
+
+    :lists.foreach(fn {field, _} ->
+      unless Keyword.has_key?(struct, field) do
+        compile_error(caller, "undefined field #{field} on struct #{Macro.to_string(name)}")
+      end
+    end, fields)
+
+    fields = Keyword.merge(struct, [__struct__: module] ++ fields)
+    typespec({:%{}, meta, fields}, vars, caller)
+  end
+
+  # Handle records
+  defp typespec({:record, meta, [atom]}, vars, caller) do
+    typespec({:record, meta, [atom, []]}, vars, caller)
+  end
+
+  defp typespec({:record, meta, [atom, fields]}, vars, caller) do
+    case Macro.expand({atom, [], [{atom, [], []}]}, caller) do
+      keyword when is_list(keyword) ->
+        keyword =
+          :lists.map(fn {field, _} ->
+            {field, quote do: term()}
+          end, keyword)
+
+        :lists.foreach(fn {field, _} ->
+          unless Keyword.has_key?(keyword, field) do
+            compile_error(caller, "undefined field #{field} on record #{inspect atom}")
+          end
+        end, fields)
+
+        fields = Keyword.merge(keyword, fields)
+        types = Keyword.values(fields)
+
+        typespec({:{}, meta, [atom|types]}, vars, caller)
+      _ ->
+        compile_error(caller, "unknown record #{inspect atom}")
+    end
  end

  # Handle ranges
  defp typespec({:.., meta, args}, vars, caller) do
-    typespec({:range, meta, args}, vars, caller)
+    args = for arg <- args, do: typespec(arg, vars, caller)
+    {:type, line(meta), :range, args}
  end

  # Handle special forms
@@ -866,11 +971,11 @@ defmodule Kernel.Typespec do
  end

  # Handle local calls
-  defp typespec({:string, meta, arguments}, vars, caller) do
-    :elixir_errors.warn caller.line, caller.file, "string() type use is discouraged. For character lists, use " <>
+  defp typespec({type, meta, arguments}, vars, caller) when type in [:string, :nonempty_string] do
+    :elixir_errors.warn caller.line, caller.file, "#{type}() type use is discouraged. For character lists, use " <>
      "char_list() type, for strings, String.t()\n#{Exception.format_stacktrace(Macro.Env.stacktrace(caller))}"
    arguments = for arg <- arguments, do: typespec(arg, vars, caller)
-    {:type, line(meta), :string, arguments}
+    {:type, line(meta), type, arguments}
  end

  defp typespec({:char_list, _meta, []}, vars, caller) do
@@ -881,10 +986,22 @@ defmodule Kernel.Typespec do
    typespec((quote do: :elixir.as_boolean(unquote(arg))), vars, caller)
  end

+  defp typespec({:fun, meta, args}, vars, caller) do
+    args = for arg <- args, do: typespec(arg, vars, caller)
+    {:type, line(meta), :fun, args}
+  end
+
  defp typespec({name, meta, arguments}, vars, caller) do
    arguments = for arg <- arguments, do: typespec(arg, vars, caller)
+
+    if :erlang.system_info(:otp_release) >= '18' do
+      arity = length(arguments)
+      type = if :erl_internal.is_type(name, arity), do: :type, else: :user_type
+      {type, line(meta), name, arguments}
+    else
      {:type, line(meta), name, arguments}
    end
+  end

  # Handle literals
  defp typespec(atom, _, _) when is_atom(atom) do
@@ -899,15 +1016,19 @@ defmodule Kernel.Typespec do
    typespec({nil, [], []}, vars, caller)
  end

+  defp typespec([{:..., _, atom}], vars, caller) when is_atom(atom) do
+    typespec({:nonempty_list, [], []}, vars, caller)
+  end
+
+  defp typespec([spec, {:..., _, atom}], vars, caller) when is_atom(atom) do
+    typespec({:nonempty_list, [], [spec]}, vars, caller)
+  end
+
  defp typespec([spec], vars, caller) do
    typespec({:list, [], [spec]}, vars, caller)
  end

-  defp typespec([spec, {:"...", _, quoted}], vars, caller) when is_atom(quoted) do
-    typespec({:nonempty_list, [], [spec]}, vars, caller)
-  end
-
-  defp typespec(list, vars, caller) do
+  defp typespec(list, vars, caller) when is_list(list) do
    [h|t] = :lists.reverse(list)
    union = :lists.foldl(fn(x, acc) ->
      {:|, [], [validate_kw(x, list, caller), acc]}
@@ -915,6 +1036,10 @@ defmodule Kernel.Typespec do
    typespec({:list, [], [union]}, vars, caller)
  end

+  defp typespec(other, _vars, caller) do
+    compile_error(caller, "unexpected expression in typespec: #{Macro.to_string other}")
+  end
+
  ## Helpers

  defp compile_error(caller, desc) do
@@ -941,7 +1066,7 @@ defmodule Kernel.Typespec do
    end
  end

-  defp fn_args(meta, [{:"...", _, _}], _vars, _caller) do
+  defp fn_args(meta, [{:..., _, _}], _vars, _caller) do
    {:type, line(meta), :any}
  end

@@ -9,19 +9,19 @@ defmodule Keyword do
  behave exactly as a dictionary and mimic the API defined
  by the `Dict` behaviour.

-  For example, `Keyword.get` will get the first entry matching
+  For example, `Keyword.get/3` will get the first entry matching
  the given key, regardless if duplicated entries exist.
-  Similarly, `Keyword.put` and `Keyword.delete` ensure all
+  Similarly, `Keyword.put/3` and `Keyword.delete/3` ensure all
  duplicated entries for a given key are removed when invoked.

  A handful of functions exist to handle duplicated keys, in
-  particular, `from_enum` allows creating a new keywords without
-  removing duplicated keys, `get_values` returns all values for
-  a given key and `delete_first` deletes just one of the existing
+  particular, `Enum.into/2` allows creating new keywords without
+  removing duplicated keys, `get_values/2` returns all values for
+  a given key and `delete_first/2` deletes just one of the existing
  entries.

  Since a keyword list is simply a list, all the operations defined
-  in `Enum` and `List` can also be applied.
+  in `Enum` and `List` can be applied.
  """

  @compile :inline_list_funcs
@@ -34,7 +34,7 @@ defmodule Keyword do
  @type t(value) :: [{key, value}]

  @doc """
-  Checks if the given argument is a keywords list or not.
+  Checks if the given argument is a keyword list or not.
  """
  @spec keyword?(term) :: boolean
  def keyword?([{key, _value} | rest]) when is_atom(key) do
@@ -56,7 +56,7 @@ defmodule Keyword do
  Creates a keyword from an enumerable.

  Duplicated entries are removed, the latest one prevails.
-  I.e. differently from `Enum.into(enumerable, [])`,
+  Unlike `Enum.into(enumerable, [])`,
  `Keyword.new(enumerable)` guarantees the keys are unique.

  ## Examples
@@ -76,7 +76,7 @@ defmodule Keyword do
  Creates a keyword from an enumerable via the transformation function.

  Duplicated entries are removed, the latest one prevails.
-  I.e. differently from `Enum.into(enumerable, [], fun)`,
+  Unlike `Enum.into(enumerable, [], fun)`,
  `Keyword.new(enumerable, fun)` guarantees the keys are unique.

  ## Examples
@@ -96,7 +96,7 @@ defmodule Keyword do
  @doc """
  Gets the value for a specific `key`.

-  If `key` does not exist, return default value (`nil` if no default value).
+  If `key` does not exist, return the default value (`nil` if no default value).

  If duplicated entries exist, the first one is returned.
  Use `get_values/2` to retrieve all entries.
@@ -124,6 +124,7 @@ defmodule Keyword do

  @doc """
  Fetches the value for a specific `key` and returns it in a tuple.
+
  If the `key` does not exist, returns `:error`.

  ## Examples
@@ -135,7 +136,7 @@ defmodule Keyword do
      :error

  """
-  @spec fetch(t, key) :: {:ok, value}
+  @spec fetch(t, key) :: {:ok, value} | :error
  def fetch(keywords, key) when is_list(keywords) and is_atom(key) do
    case :lists.keyfind(key, 1, keywords) do
      {^key, value} -> {:ok, value}
@@ -144,8 +145,9 @@ defmodule Keyword do
  end

  @doc """
-  Fetches the value for specific `key`. If `key` does not exist,
-  a `KeyError` is raised.
+  Fetches the value for specific `key`. 
+  
+  If `key` does not exist, a `KeyError` is raised.

  ## Examples

@@ -184,8 +186,9 @@ defmodule Keyword do
  end

  @doc """
-  Returns all keys from the keyword list. Duplicated
-  keys appear duplicated in the final list of keys.
+  Returns all keys from the keyword list. 
+  
+  Duplicated keys appear duplicated in the final list of keys.

  ## Examples

@@ -217,6 +220,7 @@ defmodule Keyword do

  @doc """
  Deletes the entries in the keyword list for a `key` with `value`.
+
  If no `key` with `value` exists, returns the keyword list unchanged.

  ## Examples
@@ -238,8 +242,9 @@ defmodule Keyword do

  @doc """
  Deletes the entries in the keyword list for a specific `key`.
+
  If the `key` does not exist, returns the keyword list unchanged.
-  Use `delete_first` to delete just the first entry in case of
+  Use `delete_first/2` to delete just the first entry in case of
  duplicated keys.

  ## Examples
@@ -261,6 +266,7 @@ defmodule Keyword do

  @doc """
  Deletes the first entry in the keyword list for a specific `key`.
+
  If the `key` does not exist, returns the keyword list unchanged.

  ## Examples
@@ -319,7 +325,9 @@ defmodule Keyword do
  end

  @doc """
-  Checks if two keywords are equal. I.e. they contain
+  Checks if two keywords are equal. 
+  
+  Two keywords are considered to be equal if they contain
  the same keys and those keys contain the same values.

  ## Examples
@@ -334,8 +342,9 @@ defmodule Keyword do
  end

  @doc """
-  Merges two keyword lists into one. If they have duplicated
-  entries, the one given as second argument wins.
+  Merges two keyword lists into one. 
+  
+  If they have duplicated keys, the one given in the second argument wins.

  ## Examples

@@ -350,8 +359,9 @@ defmodule Keyword do
  end

  @doc """
-  Merges two keyword lists into one. If they have duplicated
-  entries, the given function is invoked to solve conflicts.
+  Merges two keyword lists into one. 
+  
+  If they have duplicated keys, the given function is invoked to solve conflicts.

  ## Examples

@@ -392,10 +402,11 @@ defmodule Keyword do
  end

  @doc """
-  Updates the `key` with the given function. If the `key` does
-  not exist, raises `KeyError`.
+  Updates the `key` with the given function. 
  
-  If there are duplicated entries, they are all removed and only the first one
+  If the `key` does not exist, raises `KeyError`.
+
+  If there are duplicated keys, they are all removed and only the first one
  is updated.

  ## Examples
@@ -425,10 +436,11 @@ defmodule Keyword do
  end

  @doc """
-  Updates the `key` with the given function. If the `key` does
-  not exist, inserts the given `initial` value.
+  Updates the `key` with the given function. 
  
-  If there are duplicated entries, they are all removed and only the first one
+  If the `key` does not exist, inserts the given `initial` value.
+
+  If there are duplicated keys, they are all removed and only the first one
  is updated.

  ## Examples
@@ -455,8 +467,9 @@ defmodule Keyword do

  @doc """
  Takes all entries corresponding to the given keys and extracts them into a
-  separate keyword list. Returns a tuple with the new list and the old list
-  with removed keys.
+  separate keyword list. 
+  
+  Returns a tuple with the new list and the old list with removed keys.

  Keys for which there are no entires in the keyword list are ignored.

@@ -508,7 +521,7 @@ defmodule Keyword do
  end

  @doc """
-  Drops the given keys from the dict.
+  Drops the given keys from the keyword list.

  Duplicated keys are preserved in the new keyword list.

@@ -531,7 +544,7 @@ defmodule Keyword do
  Returns the first value associated with `key` in the keyword
  list as well as the keyword list without `key`.

-  All duplicated entries are removed. See `pop_first/3` for
+  All duplicated keys are removed. See `pop_first/3` for
  removing only the first entry.

  ## Examples
@@ -558,10 +571,10 @@ defmodule Keyword do

  @doc """
  Returns the first value associated with `key` in the keyword
-  list as well as the keyword list without that particular ocurrence
+  list as well as the keyword list without that particular occurrence
  of `key`.

-  Duplicated entries are not removed.
+  Duplicated keys are not removed.

  ## Examples

@@ -247,7 +247,7 @@ defmodule List do
      [a: 1, b: 2, c: 3]

  """
-  @spec keystore([tuple], any, non_neg_integer, tuple) :: [tuple]
+  @spec keystore([tuple], any, non_neg_integer, tuple) :: [tuple, ...]
  def keystore(list, key, position, new_tuple) do
    :lists.keystore(key, position + 1, list, new_tuple)
  end
@@ -307,6 +307,8 @@ defmodule List do
  @doc """
  Zips corresponding elements from each list in `list_of_lists`.

+  The zipping finishes as soon as any list terminates.
+
  ## Examples

      iex> List.zip([[1, 2], [3, 4], [5, 6]])
@@ -322,24 +324,6 @@ defmodule List do
    do_zip(list_of_lists, [])
  end

-  @doc """
-  Unzips the given list of lists or tuples into separate lists and returns a
-  list of lists.
-
-  ## Examples
-
-      iex> List.unzip([{1, 2}, {3, 4}])
-      [[1, 3], [2, 4]]
-
-      iex> List.unzip([{1, :a, "apple"}, {2, :b, "banana"}, {3, :c}])
-      [[1, 2, 3], [:a, :b, :c]]
-
-  """
-  @spec unzip([tuple]) :: [list]
-  def unzip(list) when is_list(list) do
-    :lists.map &Tuple.to_list/1, zip(list)
-  end
-
  @doc """
  Returns a list with `value` inserted at the specified `index`.
  Note that `index` is capped at the list length. Negative indices
@@ -528,7 +512,7 @@ defmodule List do
      1023

  """
-  @spec to_integer(char_list, non_neg_integer) :: integer
+  @spec to_integer(char_list, 2..36) :: integer
  def to_integer(char_list, base) do
    :erlang.list_to_integer(char_list, base)
  end
@@ -566,7 +550,7 @@ defmodule List do
      "abc"

  """
-  @spec to_string(:unicode.char_list) :: String.t
+  @spec to_string(:unicode.charlist) :: String.t
  def to_string(list) when is_list(list) do
    case :unicode.characters_to_binary(list) do
      result when is_binary(result) ->
@@ -16,7 +16,8 @@ defmodule Macro do
    :&&, :||, :<>, :++, :--, :\\, :::, :<-, :.., :|>, :=~,
    :<, :>, :->,
    :+, :-, :*, :/, :=, :|, :.,
-    :and, :or, :xor, :when, :in,
+    :and, :or, :when, :in,
+    :~>>, :<<~, :~>, :<~, :<~>, :<|>,
    :<<<, :>>>, :|||, :&&&, :^^^, :~~~]

  @doc false
@@ -35,11 +36,12 @@ defmodule Macro do
      :::                                     -> {:right, 60}
      :|                                      -> {:right, 70}
      :=                                      -> {:right, 90}
-      o when o in [:||, :|||, :or, :xor]      -> {:left, 130}
+      o when o in [:||, :|||, :or]            -> {:left, 130}
      o when o in [:&&, :&&&, :and]           -> {:left, 140}
      o when o in [:==, :!=, :=~, :===, :!==] -> {:left, 150}
      o when o in [:<, :<=, :>=, :>]          -> {:left, 160}
-      o when o in [:|>, :<<<, :>>>]           -> {:left, 170}
+      o when o in [:|>, :<<<, :>>>, :<~, :~>,
+                   :<<~, :~>>, :<~>, :<|>]    -> {:left, 170}
      :in                                     -> {:left, 180}
      o when o in [:++, :--, :.., :<>]        -> {:right, 200}
      o when o in [:+, :-]                    -> {:left, 210}
@@ -74,7 +76,7 @@ defmodule Macro do
  def pipe(expr, call_args, position)

  def pipe(expr, {:&, _, _} = call_args, _integer) do
-    raise ArgumentError, "cannot pipe #{to_string expr} into #{to_string call_args}"
+    bad_pipe(expr, call_args)
  end

  def pipe(expr, {call, line, atom}, integer) when is_atom(atom) do
@@ -86,7 +88,12 @@ defmodule Macro do
  end

  def pipe(expr, call_args, _integer) do
-    raise ArgumentError, "cannot pipe #{to_string expr} into #{to_string call_args}"
+    bad_pipe(expr, call_args)
+  end
+
+  defp bad_pipe(expr, call_args) do
+    raise ArgumentError, "cannot pipe #{to_string expr} into #{to_string call_args}, " <>
+      "can only pipe into local calls foo(), remote calls Foo.bar() or anonymous functions calls foo.()"
  end

  @doc """
@@ -300,6 +307,40 @@ defmodule Macro do
    elem(:elixir_quote.escape(expr, Keyword.get(opts, :unquote, false)), 0)
  end

+  @doc """
+  Validates the given expressions are valid quoted expressions.
+
+  Check the `type:Macro.t` for the specification of a valid
+  quoted expression.
+  """
+  @spec validate(term) :: :ok | {:error, term}
+  def validate(expr) do
+    find_invalid(expr) || :ok
+  end
+
+  defp find_invalid({left, right}), do:
+    find_invalid(left) || find_invalid(right)
+
+  defp find_invalid({left, meta, right}) when is_list(meta) and (is_atom(right) or is_list(right)), do:
+    find_invalid(left) || find_invalid(right)
+
+  defp find_invalid(list) when is_list(list), do:
+    Enum.find_value(list, &find_invalid/1)
+
+  defp find_invalid(pid)  when is_pid(pid),    do: nil
+  defp find_invalid(atom) when is_atom(atom),  do: nil
+  defp find_invalid(num)  when is_number(num), do: nil
+  defp find_invalid(bin)  when is_binary(bin), do: nil
+
+  defp find_invalid(fun) when is_function(fun) do
+    unless :erlang.fun_info(fun, :env) == {:env, []} and
+           :erlang.fun_info(fun, :type) == {:type, :external} do
+      {:error, fun}
+    end
+  end
+
+  defp find_invalid(other), do: {:error, other}
+
  @doc ~S"""
  Unescape the given chars.

@@ -307,9 +348,9 @@ defmodule Macro do
  single- and double-quoted strings. Check `unescape_string/2`
  for information on how to customize the escaping map.

-  In this setup, Elixir will escape the following: `\a`, `\b`,
-  `\d`, `\e`, `\f`, `\n`, `\r`, `\s`, `\t` and `\v`. Octals are
-  also escaped according to the latin1 set they represent.
+  In this setup, Elixir will escape the following: `\0`, `\a`, `\b`,
+  `\d`, `\e`, `\f`, `\n`, `\r`, `\s`, `\t` and `\v`. Hexadecimals
+  are also supported via `\xNN` and `\x{NN...}` syntax.

  This function is commonly used on sigil implementations
  (like `~r`, `~s` and others) which receive a raw, unescaped
@@ -340,6 +381,7 @@ defmodule Macro do
  representing the codepoint of the character it wants to unescape.
  Here is the default mapping function implemented by Elixir:

+      def unescape_map(?0), do: ?0
      def unescape_map(?a), do: ?\a
      def unescape_map(?b), do: ?\b
      def unescape_map(?d), do: ?\d
@@ -350,20 +392,14 @@ defmodule Macro do
      def unescape_map(?s), do: ?\s
      def unescape_map(?t), do: ?\t
      def unescape_map(?v), do: ?\v
+      def unescape_map(?x), do: true
      def unescape_map(e),  do: e

  If the `unescape_map` function returns `false`. The char is
  not escaped and `\` is kept in the char list.

-  ## Octals
-
-  Octals will by default be escaped unless the map function
-  returns `false` for `?0`.
-
-  ## Hex
-
-  Hexadecimals will by default be escaped unless the map function
-  returns `false` for `?x`.
+  Hexadecimals will be escaped if the map function returns `true`
+  for `?x`.

  ## Examples

@@ -525,12 +561,16 @@ defmodule Macro do

  # All other calls
  def to_string({target, _, args} = ast, fun) when is_list(args) do
+    if sigil = sigil_call(ast, fun) do
+      sigil
+    else
      {list, last} = :elixir_utils.split_last(args)
      fun.(ast, case kw_blocks?(last) do
        true  -> call_to_string_with_args(target, list, fun) <> kw_blocks_to_string(last, fun)
        false -> call_to_string_with_args(target, args, fun)
      end)
    end
+  end

  # Two-item tuples
  def to_string({left, right}, fun) do
@@ -565,6 +605,26 @@ defmodule Macro do
  defp module_to_string(atom, _fun) when is_atom(atom), do: inspect(atom, [])
  defp module_to_string(other, fun), do: call_to_string(other, fun)

+  defp sigil_call({func, _, [{:<<>>, _, [string]}, args]} = ast, fun) when is_list(args) do
+    sigil =
+      case Atom.to_string(func) do
+        <<"sigil_", name>> ->
+          "~" <> <<name>> <>
+          fun.(string, inspect(string, [])) <>
+          sigil_args(args, fun)
+        _ ->
+          nil
+      end
+    fun.(ast, sigil)
+  end
+
+  defp sigil_call(_other, _fun) do
+    nil
+  end
+
+  defp sigil_args([], _fun),   do: ""
+  defp sigil_args(args, fun), do: fun.(args, List.to_string(args))
+
  defp call_to_string(atom, _fun) when is_atom(atom), do: Atom.to_string(atom)
  defp call_to_string({:., _, [arg]}, fun),           do: module_to_string(arg, fun) <> "."
  defp call_to_string({:., _, [left, right]}, fun),   do: module_to_string(left, fun) <> "." <> call_to_string(right, fun)
@@ -773,7 +833,7 @@ defmodule Macro do
        :elixir_lexical.record_remote(receiver, env.lexical_tracker)
        {receiver, true}
      aliases ->
-        aliases = for alias <- aliases, do: elem(do_expand_once(alias, env), 0)
+        aliases = :lists.map(&elem(do_expand_once(&1, env), 0), aliases)

        case :lists.all(&is_atom/1, aliases) do
          true ->
@@ -838,7 +898,7 @@ defmodule Macro do
      end

      expand = :elixir_dispatch.expand_import(meta, {atom, length(args)}, args,
-                                              env, extra)
+                                              env, extra, true)

      case expand do
        {:ok, receiver, quoted} ->
@@ -879,7 +939,7 @@ defmodule Macro do
  be expanded.

  This function uses `expand_once/2` under the hood. Check
-  `expand_once/2` for more information and exmaples.
+  `expand_once/2` for more information and examples.
  """
  def expand(tree, env) do
    expand_until({tree, true}, env)
@@ -4,7 +4,22 @@ defmodule Macro.Env do

  The current environment can be accessed at any time as
  `__ENV__`. Inside macros, the caller environment can be
-  accessed as `__CALLER__`. It contains the following fields:
+  accessed as `__CALLER__`.
+
+  An instance of `Macro.Env` must not be modified by hand. If you need to
+  create a custom environment to pass to `Code.eval_quoted/3`, use the
+  following trick:
+
+      def make_custom_env do
+        import SomeModule, only: [some_function: 2]
+        alias A.B.C
+        __ENV__
+      end
+
+  You may then call `make_custom_env()` to get a struct with the desired
+  imports and aliases included.
+
+  It contains the following fields:

    * `module` - the current module name
    * `file` - the current file name as a binary
@@ -29,7 +44,7 @@ defmodule Macro.Env do
    * `local` - the module to expand local functions to
  """

-  @type name_arity :: {atom, non_neg_integer}
+  @type name_arity :: {atom, arity}
  @type file :: binary
  @type line :: non_neg_integer
  @type aliases :: [{module, module}]
@@ -42,10 +57,10 @@ defmodule Macro.Env do
  @type vars :: [{atom, atom | non_neg_integer}]
  @type export_vars :: vars | nil
  @type lexical_tracker :: pid
-  @type local :: module | nil
+  @type local :: atom | nil

  @type t :: %{__struct__: __MODULE__,
-               module: module,
+               module: atom,
               file: file,
               line: line,
               function: name_arity | nil,
@@ -105,9 +120,9 @@ defmodule Macro.Env do
  """
  def stacktrace(%{__struct__: Macro.Env} = env) do
    cond do
-      nil?(env.module) ->
+      is_nil(env.module) ->
        [{:elixir_compiler, :__FILE__, 1, relative_location(env)}]
-      nil?(env.function) ->
+      is_nil(env.function) ->
        [{env.module, :__MODULE__, 0, relative_location(env)}]
      true ->
        {name, arity} = env.function
@@ -38,5 +38,32 @@ defmodule Map do
    end, map1, map2
  end

+  @doc """
+  Converts a struct to map.
+
+  It accepts the struct module or a struct itself and
+  simply removes the `__struct__` field from the struct.
+
+  ## Example
+
+      defmodule User do
+        defstruct [:name]
+      end
+
+      Map.from_struct(User)
+      #=> %{name: nil}
+
+      Map.from_struct(%User{name: "john"})
+      #=> %{name: "john"}
+
+  """
+  def from_struct(struct) when is_atom(struct) do
+    :maps.remove(:__struct__, struct.__struct__)
+  end
+
+  def from_struct(%{__struct__: _} = struct) do
+    :maps.remove(:__struct__, struct)
+  end
+
  def equal?(%{} = map1, %{} = map2), do: map1 === map2
 end
@@ -85,6 +85,9 @@ defmodule Module do
      See http://www.erlang.org/doc/man/compile.html for the list of supported
      options.

+      Several uses of `@compile` will accumulate instead of overriding
+      previous ones.
+
      ### Example

            defmodule M do
@@ -476,19 +479,6 @@ defmodule Module do
    :elixir_aliases.safe_concat([left, right])
  end

-  @doc """
-  Gets an anonymous function from the given module, function
-  and arity. The module and function are not verified to exist.
-
-      iex> fun = Module.function(Kernel, :is_atom, 1)
-      iex> fun.(:hello)
-      true
-
-  """
-  def function(mod, fun, arity) do
-    :erlang.make_fun(mod, fun, arity)
-  end
-
  @doc """
  Attaches documentation to a given function or type. It expects
  the module the function/type belongs to, the line (a non negative
@@ -514,23 +504,23 @@ defmodule Module do
  def add_doc(module, line, kind, tuple, signature, doc) when
      kind in [:def, :defmacro, :type, :opaque] and (is_binary(doc) or is_boolean(doc) or doc == nil) do
    assert_not_compiled!(:add_doc, module)
-    table = docs_table_for(module)
+    table = data_table_for(module)

    {signature, _} = :lists.mapfoldl fn(x, acc) ->
      {simplify_signature(x, acc), acc + 1}
    end, 1, signature

-    case :ets.lookup(table, tuple) do
+    case :ets.lookup(table, {:doc, tuple}) do
      [] ->
-        :ets.insert(table, {tuple, line, kind, signature, doc})
+        :ets.insert(table, {{:doc, tuple}, line, kind, signature, doc})
        :ok
-      [{tuple, line, _old_kind, old_sign, old_doc}] ->
+      [{doc_tuple, line, _old_kind, old_sign, old_doc}] ->
        :ets.insert(table, {
-          tuple,
+          doc_tuple,
          line,
          kind,
          merge_signatures(old_sign, signature, 1),
-          if(nil?(doc), do: old_doc, else: doc)
+          if(is_nil(doc), do: old_doc, else: doc)
       })
        :ok
    end
@@ -622,7 +612,7 @@ defmodule Module do
  """
  def defines?(module, tuple) when is_tuple(tuple) do
    assert_not_compiled!(:defines?, module)
-    table = function_table_for(module)
+    table = defs_table_for(module)
    :ets.lookup(table, tuple) != []
  end

@@ -642,7 +632,7 @@ defmodule Module do
  """
  def defines?(module, tuple, kind) do
    assert_not_compiled!(:defines?, module)
-    table = function_table_for(module)
+    table = defs_table_for(module)
    case :ets.lookup(table, tuple) do
      [{_, ^kind, _, _, _, _, _}] -> true
      _ -> false
@@ -662,8 +652,8 @@ defmodule Module do
  """
  def definitions_in(module) do
    assert_not_compiled!(:definitions_in, module)
-    table = function_table_for(module)
-    for {tuple, _, _, _, _, _, _} <- :ets.tab2list(table), do: tuple
+    table = defs_table_for(module)
+    :lists.concat :ets.match(table, {:'$1', :_, :_, :_, :_, :_, :_})
  end

  @doc """
@@ -681,8 +671,8 @@ defmodule Module do
  """
  def definitions_in(module, kind) do
    assert_not_compiled!(:definitions_in, module)
-    table = function_table_for(module)
-    for {tuple, stored_kind, _, _, _, _, _} <- :ets.tab2list(table), stored_kind == kind, do: tuple
+    table = defs_table_for(module)
+    :lists.concat :ets.match(table, {:'$1', kind, :_, :_, :_, :_, :_})
  end

  @doc """
@@ -694,7 +684,7 @@ defmodule Module do
  def make_overridable(module, tuples) do
    assert_not_compiled!(:make_overridable, module)

-    for tuple <- tuples do
+    :lists.foreach(fn tuple ->
      case :elixir_def.lookup_definition(module, tuple) do
        false ->
          {name, arity} = tuple
@@ -702,27 +692,26 @@ defmodule Module do
        clause ->
          :elixir_def.delete_definition(module, tuple)

-          neighbours = if loaded?(Module.LocalsTracker) do
-            Module.LocalsTracker.yank(module, tuple)
-          else
+          neighbours = if :elixir_compiler.get_opt(:internal) do
            []
+          else
+            Module.LocalsTracker.yank(module, tuple)
          end

-          old    = get_attribute(module, :__overridable)
+          old    = :elixir_def_overridable.overridable(module)
          merged = :orddict.update(tuple, fn({count, _, _, _}) ->
            {count + 1, clause, neighbours, false}
          end, {1, clause, neighbours, false}, old)
-
-          put_attribute(module, :__overridable, merged)
-      end
+          :elixir_def_overridable.overridable(module, merged)
      end
+    end, tuples)
  end

  @doc """
  Returns `true` if `tuple` in `module` is marked as overridable.
  """
  def overridable?(module, tuple) do
-    !!List.keyfind(get_attribute(module, :__overridable), tuple, 0)
+    !!List.keyfind(:elixir_def_overridable.overridable(module), tuple, 0)
  end

  @doc """
@@ -741,7 +730,7 @@ defmodule Module do
    assert_not_compiled!(:put_attribute, module)
    table = data_table_for(module)
    value = normalize_attribute(key, value)
-    acc   = :ets.lookup_element(table, :__acc_attributes, 2)
+    acc   = :ets.lookup_element(table, {:elixir, :acc_attributes}, 2)

    new =
      if :lists.member(key, acc) do
@@ -766,15 +755,9 @@ defmodule Module do

      @foo

-  Expands to:
+  Expands close to:

-      Module.get_attribute(__MODULE__, :foo, true)
-
-  Notice the third argument may be given to indicate a stacktrace
-  to be emitted when the attribute was not previously defined.
-  The default value for `warn` is nil for direct calls but the `@foo`
-  macro sets it to the proper stacktrace automatically, warning
-  every time `@foo` is used but not set previously.
+      Module.get_attribute(__MODULE__, :foo)

  ## Examples

@@ -788,37 +771,9 @@ defmodule Module do
      end

  """
-  @spec get_attribute(module, atom, warn :: nil | [tuple]) :: term
-  def get_attribute(module, key, warn \\ nil) when
-      is_atom(key) and (is_list(warn) or nil?(warn)) do
-    assert_not_compiled!(:get_attribute, module)
-    table = data_table_for(module)
-
-    case :ets.lookup(table, key) do
-      [{^key, val}] -> val
-      [] ->
-        acc = :ets.lookup_element(table, :__acc_attributes, 2)
-
-        cond do
-          :lists.member(key, acc) ->
-            []
-          is_list(warn) ->
-            :elixir_errors.warn warn_info(warn), "undefined module attribute @#{key}, " <>
-              "please remove access to @#{key} or explicitly set it to nil before access\n"
-            nil
-          true ->
-            nil
-        end
-    end
-  end
-
-  defp warn_info([entry|_]) do
-    opts = elem(entry, tuple_size(entry) - 1)
-    Exception.format_file_line(Keyword.get(opts, :file), Keyword.get(opts, :line)) <> " "
-  end
-
-  defp warn_info([]) do
-    ""
+  @spec get_attribute(atom, atom) :: term
+  def get_attribute(module, key) do
+    get_attribute(module, key, nil)
  end

  @doc """
@@ -832,10 +787,12 @@ defmodule Module do
      end

  """
+  @spec delete_attribute(atom, atom) :: :ok
  def delete_attribute(module, key) when is_atom(key) do
    assert_not_compiled!(:delete_attribute, module)
    table = data_table_for(module)
    :ets.delete(table, key)
+    :ok
  end

  @doc """
@@ -874,13 +831,13 @@ defmodule Module do
    table = data_table_for(module)

    if Keyword.get(opts, :persist) do
-      old = :ets.lookup_element(table, :__persisted_attributes, 2)
-      :ets.insert(table, {:__persisted_attributes,  [new|old]})
+      old = :ets.lookup_element(table, {:elixir, :persisted_attributes}, 2)
+      :ets.insert(table, {{:elixir, :persisted_attributes}, [new|old]})
    end

    if Keyword.get(opts, :accumulate) do
-      old = :ets.lookup_element(table, :__acc_attributes, 2)
-      :ets.insert(table, {:__acc_attributes,  [new|old]})
+      old = :ets.lookup_element(table, {:elixir, :acc_attributes}, 2)
+      :ets.insert(table, {{:elixir, :acc_attributes}, [new|old]})
    end
  end

@@ -911,7 +868,9 @@ defmodule Module do
      :ok ->
        :ok
      {:error, :private_doc} ->
-        :elixir_errors.warn line, env.file, "function #{name}/#{arity} is private, @doc's are always discarded for private functions\n"
+        :elixir_errors.warn line, env.file,
+          "function #{name}/#{arity} is private, " <>
+          "@doc's are always discarded for private functions"
    end

    delete_attribute(module, :doc)
@@ -933,6 +892,38 @@ defmodule Module do
    :ets.insert(table, {key, new})
  end

+  @doc false
+  def get_attribute(module, key, warn) when is_atom(key) and (is_list(warn) or is_nil(warn)) do
+    assert_not_compiled!(:get_attribute, module)
+    table = data_table_for(module)
+
+    case :ets.lookup(table, key) do
+      [{^key, val}] -> val
+      [] ->
+        acc = :ets.lookup_element(table, {:elixir, :acc_attributes}, 2)
+
+        cond do
+          :lists.member(key, acc) ->
+            []
+          is_list(warn) ->
+            :elixir_errors.warn warn_info(warn), "undefined module attribute @#{key}, " <>
+              "please remove access to @#{key} or explicitly set it to nil before access"
+            nil
+          true ->
+            nil
+        end
+    end
+  end
+
+  defp warn_info([entry|_]) do
+    opts = elem(entry, tuple_size(entry) - 1)
+    Exception.format_file_line(Keyword.get(opts, :file), Keyword.get(opts, :line)) <> " "
+  end
+
+  defp warn_info([]) do
+    ""
+  end
+
  ## Helpers

  defp normalize_attribute(:on_load, atom) when is_atom(atom) do
@@ -940,7 +931,8 @@ defmodule Module do
  end

  defp normalize_attribute(:behaviour, atom) when is_atom(atom) do
-    Code.ensure_compiled(atom)
+    # Attempt to compile behaviour but ignore failure (will warn later)
+    _ = Code.ensure_compiled(atom)
    atom
  end

@@ -963,15 +955,11 @@ defmodule Module do
  end

  defp data_table_for(module) do
-    module
+    :elixir_module.data_table(module)
  end

-  defp function_table_for(module) do
-    :elixir_def.table(module)
-  end
-
-  defp docs_table_for(module) do
-    :elixir_module.docs_table(module)
+  defp defs_table_for(module) do
+    :elixir_module.defs_table(module)
  end

  defp assert_not_compiled!(fun, module) do
@@ -979,6 +967,4 @@ defmodule Module do
      raise ArgumentError,
        "could not call #{fun} on module #{inspect module} because it was already compiled"
  end
-
-  defp loaded?(module), do: is_tuple :code.is_loaded(module)
 end
@@ -65,22 +65,25 @@ defmodule Module.LocalsTracker do
  """
  @spec reachable(ref) :: [local]
  def reachable(ref) do
-    d = :gen_server.call(to_pid(ref), :digraph, @timeout)
-    reduce_reachable(d, :local, [])
+    reachable_from(:gen_server.call(to_pid(ref), :digraph, @timeout), :local)
+  end
+
+  defp reachable_from(d, starting) do
+    :sets.to_list(reduce_reachable(d, starting, :sets.new))
  end

  defp reduce_reachable(d, vertex, vertices) do
    neighbours = :digraph.out_neighbours(d, vertex)
-    neighbours = (for {_, _} = t <- neighbours, do: t) |> :ordsets.from_list
-    remaining  = :ordsets.subtract(neighbours, vertices)
-    vertices   = :ordsets.union(neighbours, vertices)
-    :lists.foldl(&reduce_reachable(d, &1, &2), vertices, remaining)
+    neighbours = (for {_, _} = t <- neighbours, do: t) |> :sets.from_list
+    remaining  = :sets.subtract(neighbours, vertices)
+    vertices   = :sets.union(neighbours, vertices)
+    :sets.fold(&reduce_reachable(d, &1, &2), vertices, remaining)
  end

  defp to_pid(pid) when is_pid(pid),  do: pid
  defp to_pid(mod) when is_atom(mod) do
    table = :elixir_module.data_table(mod)
-    [{_, val}] = :ets.lookup(table, :__locals_tracker)
+    [{_, val}] = :ets.lookup(table, {:elixir, :locals_tracker})
    val
  end

@@ -89,8 +92,7 @@ defmodule Module.LocalsTracker do
  # Starts the tracker and returns its pid.
  @doc false
  def start_link do
-    {:ok, pid} = :gen_server.start_link(__MODULE__, [], [])
-    pid
+    :gen_server.start_link(__MODULE__, [], [])
  end

  # Adds a definition into the tracker. A public
@@ -134,9 +136,7 @@ defmodule Module.LocalsTracker do
  # Reattach a previously yanked node
  @doc false
  def reattach(pid, kind, tuple, neighbours) do
-    pid = to_pid(pid)
-    add_definition(pid, kind, tuple)
-    :gen_server.cast(pid, {:reattach, tuple, neighbours})
+    :gen_server.cast(to_pid(pid), {:reattach, kind, tuple, neighbours})
  end

  # Collecting all conflicting imports with the given functions
@@ -156,12 +156,42 @@ defmodule Module.LocalsTracker do
  # given also accounting the expected amount of default
  # clauses a private function have.
  @doc false
-  def collect_unused_locals(pid, private) do
-    reachable = reachable(pid)
-    :lists.foldl(&collect_unused_locals(&1, &2, reachable), [], private)
+  def collect_unused_locals(ref, private) do
+    d = :gen_server.call(to_pid(ref), :digraph, @timeout)
+    {unreachable(d, private), collect_warnings(d, private)}
  end

-  defp collect_unused_locals({tuple, kind, 0}, acc, reachable) do
+  defp unreachable(d, private) do
+    unreachable = for {tuple, _, _} <- private, do: tuple
+
+    private =
+      for {tuple, :defp, _} <- private do
+        neighbours = :digraph.in_neighbours(d, tuple)
+        neighbours = for {_, _} = t <- neighbours, do: t
+        {tuple, :sets.from_list(neighbours)}
+      end
+
+    reduce_unreachable(private, [], :sets.from_list(unreachable))
+  end
+
+  defp reduce_unreachable([{vertex, callers}|t], acc, unreachable) do
+    if :sets.is_subset(callers, unreachable) do
+      reduce_unreachable(t, [{vertex, callers}|acc], unreachable)
+    else
+      reduce_unreachable(acc ++ t, [], :sets.del_element(vertex, unreachable))
+    end
+  end
+
+  defp reduce_unreachable([], _acc, unreachable) do
+    :sets.to_list(unreachable)
+  end
+
+  defp collect_warnings(d, private) do
+    reachable = reachable_from(d, :local)
+    :lists.foldl(&collect_warnings(&1, &2, reachable), [], private)
+  end
+
+  defp collect_warnings({tuple, kind, 0}, acc, reachable) do
    if :lists.member(tuple, reachable) do
      acc
    else
@@ -169,7 +199,7 @@ defmodule Module.LocalsTracker do
    end
  end

-  defp collect_unused_locals({tuple, kind, default}, acc, reachable) when default > 0 do
+  defp collect_warnings({tuple, kind, default}, acc, reachable) when default > 0 do
    {name, arity} = tuple
    min = arity - default
    max = arity
@@ -211,6 +241,7 @@ defmodule Module.LocalsTracker do
    {:ok, {d, []}}
  end

+  @doc false
  def handle_call({:cache_env, env}, _from, {d, cache}) do
    case cache do
      [{i,^env}|_] ->
@@ -227,10 +258,9 @@ defmodule Module.LocalsTracker do
  end

  def handle_call({:yank, local}, _from, {d, _} = state) do
-    in_vertices  = :digraph.in_neighbours(d, local)
    out_vertices = :digraph.out_neighbours(d, local)
-    :digraph.del_vertex(d, local)
-    {:reply, {in_vertices, out_vertices}, state}
+    :digraph.del_edges(d, :digraph.out_edges(d, local))
+    {:reply, {[], out_vertices}, state}
  end

  def handle_call(:digraph, _from, {d, _} = state) do
@@ -241,6 +271,7 @@ defmodule Module.LocalsTracker do
    {:stop, {:bad_call, request}, state}
  end

+  @doc false
  def handle_info(_msg, state) do
    {:noreply, state}
  end
@@ -268,9 +299,17 @@ defmodule Module.LocalsTracker do
    {:noreply, state}
  end

-  def handle_cast({:reattach, tuple, {in_neigh, out_neigh}}, {d, _} = state) do
-    for from <- in_neigh, do: replace_edge(d, from, tuple)
-    for to <- out_neigh, do: replace_edge(d, tuple, to)
+  def handle_cast({:reattach, _kind, tuple, {in_neigh, out_neigh}}, {d, _} = state) do
+    for from <- in_neigh do
+      :digraph.add_vertex(d, from)
+      replace_edge!(d, from, tuple)
+    end
+
+    for to <- out_neigh do
+      :digraph.add_vertex(d, to)
+      replace_edge!(d, tuple, to)
+    end
+
    {:noreply, state}
  end

@@ -282,10 +321,12 @@ defmodule Module.LocalsTracker do
    {:stop, {:bad_cast, msg}, state}
  end

+  @doc false
  def terminate(_reason, _state) do
    :ok
  end

+  @doc false
  def code_change(_old, state, _extra) do
    {:ok, state}
  end
@@ -300,6 +341,8 @@ defmodule Module.LocalsTracker do
    if function != nil do
      replace_edge!(d, function, tuple)
    end
+
+    :ok
  end

  defp handle_add_local(d, from, to) do
@@ -317,14 +360,9 @@ defmodule Module.LocalsTracker do
  end

  defp replace_edge!(d, from, to) do
-    unless :lists.member(to, :digraph.out_neighbours(d, from)) do
+    _ = unless :lists.member(to, :digraph.out_neighbours(d, from)) do
      [:"$e"|_] = :digraph.add_edge(d, from, to)
    end
-  end
-
-  defp replace_edge(d, from, to) do
-    unless :lists.member(to, :digraph.out_neighbours(d, from)) do
-      :digraph.add_edge(d, from, to)
-    end
+    :ok
  end
 end
@@ -30,7 +30,7 @@ defmodule Node do
  returns `{:error, :not_allowed}`. Returns `{:error, :not_found}` if the
  local node is not alive.
  """
-  @spec stop() :: :ok | {:error, term}
+  @spec stop() :: :ok | {:error, :not_allowed | :not_found}
  def stop() do
    :net_kernel.stop()
  end
@@ -45,7 +45,7 @@ defmodule OptionParser do
    * `:strict` - the switches are strict. Any switch that does not
      exist in the switch list is treated as an error.

-    * `:switches` - configure some switches. Switches that does not
+    * `:switches` - defines some switches. Switches that does not
      exist in the switch list are still attempted to be parsed.

  Note only `:strict` or `:switches` may be given at once.
@@ -59,7 +59,7 @@ defmodule OptionParser do
    * `:float`   - parses the switch as a float.
    * `:string`  - returns the switch as a string.

-  If a switch can't be parsed or is not specfied in the strict case,
+  If a switch can't be parsed or is not specified in the strict case,
  the option is returned in the invalid options list (third element
  of the returned tuple).

@@ -91,14 +91,8 @@ defmodule OptionParser do

  ## Negation switches

-  All switches starting with `--no-` are considered to be booleans and never
-  parse the next value:
-
-      iex> OptionParser.parse(["--no-op", "path/to/file"])
-      {[no_op: true], ["path/to/file"], []}
-
-  However, in case the base switch exists, it sets that particular switch to
-  false:
+  In case a switch is declared as boolean, it may be passed as `--no-SWITCH`
+  which will set the option to false:

      iex> OptionParser.parse(["--no-op", "path/to/file"], switches: [op: :boolean])
      {[op: false], ["path/to/file"], []}
@@ -113,8 +107,7 @@ defmodule OptionParser do
  """
  @spec parse(argv, options) :: {parsed, argv, errors}
  def parse(argv, opts \\ []) when is_list(argv) and is_list(opts) do
-    config = compile_config(opts, true)
-    do_parse(argv, config, [], [], [])
+    do_parse(argv, compile_config(opts), [], [], [], true)
  end

  @doc """
@@ -134,37 +127,36 @@ defmodule OptionParser do
  """
  @spec parse_head(argv, options) :: {parsed, argv, errors}
  def parse_head(argv, opts \\ []) when is_list(argv) and is_list(opts) do
-    config = compile_config(opts, false)
-    do_parse(argv, config, [], [], [])
+    do_parse(argv, compile_config(opts), [], [], [], false)
  end

-  defp do_parse([], _config, opts, args, invalid) do
+  defp do_parse([], _config, opts, args, invalid, _all?) do
    {Enum.reverse(opts), Enum.reverse(args), Enum.reverse(invalid)}
  end

-  defp do_parse(argv, {aliases, switches, strict, all}=config, opts, args, invalid) do
+  defp do_parse(argv, {aliases, switches, strict}=config, opts, args, invalid, all?) do
    case next(argv, aliases, switches, strict) do
      {:ok, option, value, rest} ->
        # the option exist and it was successfully parsed
        kinds = List.wrap Keyword.get(switches, option)
        new_opts = do_store_option(opts, option, value, kinds)
-        do_parse(rest, config, new_opts, args, invalid)
+        do_parse(rest, config, new_opts, args, invalid, all?)

      {:invalid, option, value, rest} ->
        # the option exist but it has wrong value
-        do_parse(rest, config, opts, args, [{option, value}|invalid])
+        do_parse(rest, config, opts, args, [{option, value}|invalid], all?)

      {:undefined, option, _value, rest} ->
        # the option does not exist (for strict cases)
-        do_parse(rest, config, opts, args, [{option, nil}|invalid])
+        do_parse(rest, config, opts, args, [{option, nil}|invalid], all?)

      {:error, ["--"|rest]} ->
        {Enum.reverse(opts), Enum.reverse(args, rest), Enum.reverse(invalid)}

      {:error, [arg|rest]=remaining_args} ->
        # there is no option
-        if all do
-          do_parse(rest, config, opts, [arg|args], invalid)
+        if all? do
+          do_parse(rest, config, opts, [arg|args], invalid, all?)
        else
          {Enum.reverse(opts), Enum.reverse(args, remaining_args), Enum.reverse(invalid)}
        end
@@ -193,12 +185,12 @@ defmodule OptionParser do

  @spec next(argv, options) ::
        {:ok, key :: atom, value :: term, argv} |
-        {:invalid, key :: atom, value :: term, argv} |
-        {:undefined, key :: atom, value :: term, argv} |
+        {:invalid, String.t, String.t | nil, argv} |
+        {:undefined, String.t, String.t | nil, argv} |
        {:error, argv}

  def next(argv, opts \\ []) when is_list(argv) and is_list(opts) do
-    {aliases, switches, strict, _} = compile_config(opts, true)
+    {aliases, switches, strict} = compile_config(opts)
    next(argv, aliases, switches, strict)
  end

@@ -221,7 +213,7 @@ defmodule OptionParser do
  defp next(["-" <> option|rest], aliases, switches, strict) do
    {option, value} = split_option(option)
    opt_name_bin = "-" <> option
-    tagged = tag_option(option, value, switches, aliases)
+    tagged = tag_option(option, switches, aliases)

    if strict and not option_defined?(tagged, switches) do
      {:undefined, opt_name_bin, value, rest}
@@ -239,9 +231,95 @@ defmodule OptionParser do
    {:error, argv}
  end

+  @doc """
+  Receives a key-value enumerable and convert it to argv.
+
+  Keys must be atoms. Keys with nil value are discarded,
+  boolean values are converted to `--key` or `--no-key`
+  and all other values are converted using `to_string/1`.
+
+  ## Examples
+
+      iex>  OptionParser.to_argv([foo_bar: "baz"])
+      ["--foo-bar", "baz"]
+
+      iex>  OptionParser.to_argv([bool: true, bool: false, discarded: nil])
+      ["--bool", "--no-bool"]
+
+  """
+  @spec to_argv(Enumerable.t) :: argv
+  def to_argv(enum) do
+    Enum.flat_map(enum, fn
+      {_key, nil}  -> []
+      {key, true}  -> [to_switch(key)]
+      {key, false} -> [to_switch(key, "--no-")]
+      {key, value} -> [to_switch(key), to_string(value)]
+    end)
+  end
+
+  defp to_switch(key, prefix \\ "--") when is_atom(key) do
+    prefix <> String.replace(Atom.to_string(key), "_", "-")
+  end
+
+  @doc ~S"""
+  Splits a string into argv chunks.
+
+  ## Examples
+
+      iex> OptionParser.split("foo bar")
+      ["foo", "bar"]
+
+      iex> OptionParser.split("foo \"bar baz\"")
+      ["foo", "bar baz"]
+  """
+  @spec split(String.t) :: argv
+  def split(string) do
+    do_split(strip_leading_spaces(string), "", [], nil)
+  end
+
+  # If we have a escaped quote, simply remove the escape
+  defp do_split(<<?\\, quote, t :: binary>>, buffer, acc, quote),
+    do: do_split(t, <<buffer::binary, quote>>, acc, quote)
+
+  # If we have a quote and we were not in a quote, start one
+  defp do_split(<<quote, t :: binary>>, buffer, acc, nil) when quote in [?", ?'],
+    do: do_split(t, buffer, acc, quote)
+
+  # If we have a quote and we were inside it, close it
+  defp do_split(<<quote, t :: binary>>, buffer, acc, quote),
+    do: do_split(t, buffer, acc, nil)
+
+  # If we have a escaped quote/space, simply remove the escape as long as we are not inside a quote
+  defp do_split(<<?\\, h, t :: binary>>, buffer, acc, nil) when h in [?\s, ?', ?"],
+    do: do_split(t, <<buffer::binary, h>>, acc, nil)
+
+  # If we have space and we are outside of a quote, start new segment
+  defp do_split(<<?\s, t :: binary>>, buffer, acc, nil),
+    do: do_split(strip_leading_spaces(t), "", [buffer|acc], nil)
+
+  # All other characters are moved to buffer
+  defp do_split(<<h, t::binary>>, buffer, acc, quote) do
+    do_split(t, <<buffer::binary, h>>, acc, quote)
+  end
+
+  # Finish the string expecting a nil marker
+  defp do_split(<<>>, "", acc, nil),
+    do: Enum.reverse(acc)
+
+  defp do_split(<<>>, buffer, acc, nil),
+    do: Enum.reverse([buffer|acc])
+
+  # Otherwise raise
+  defp do_split(<<>>, _, _acc, marker) do
+    raise "argv string did not terminate properly, a #{<<marker>>} was opened but never closed"
+  end
+
+  defp strip_leading_spaces(" " <> t), do: strip_leading_spaces(t)
+  defp strip_leading_spaces(t), do: t
+
  ## Helpers

-  defp compile_config(opts, all) do
+  defp compile_config(opts) do
    aliases = opts[:aliases] || []

    {switches, strict} = cond do
@@ -253,7 +331,7 @@ defmodule OptionParser do
        {[], false}
    end

-    {aliases, switches, strict, all}
+    {aliases, switches, strict}
  end

  defp validate_option(value, kinds) do
@@ -296,11 +374,11 @@ defmodule OptionParser do
    end
  end

-  defp tag_option(<<?-, option :: binary>>, value, switches, _aliases) do
-    get_negated(option, value, switches)
+  defp tag_option(<<?-, option :: binary>>, switches, _aliases) do
+    get_negated(option, switches)
  end

-  defp tag_option(option, _value, _switches, aliases) when is_binary(option) do
+  defp tag_option(option, _switches, aliases) when is_binary(option) do
    opt = get_option(option)
    if alias = aliases[opt] do
      {:default, alias}
@@ -325,21 +403,12 @@ defmodule OptionParser do
    {nil, [:invalid], value}
  end

-  defp normalize_option({:negated, option}, nil, switches) do
-    kinds = List.wrap(switches[option])
-
-    cond do
-      :boolean in kinds ->
-        {option, kinds, false}
-      kinds == [] ->
-        {option, kinds, true}
-      true ->
-        {reverse_negated(option), [:invalid], nil}
-    end
-  end
-
-  defp normalize_option({:negated, option}, value, _switches) do
+  defp normalize_option({:negated, option}, value, switches) do
+    if value do
      {option, [:invalid], value}
+    else
+      {option, List.wrap(switches[option]), false}
+    end
  end

  defp normalize_option({:default, option}, value, switches) do
@@ -396,24 +465,18 @@ defmodule OptionParser do
    end
  end

-  defp reverse_negated(negated) do
-    String.to_atom("no_" <> Atom.to_string(negated))
-  end
-
-  defp get_negated("no-" <> rest = option, value, switches) do
-    if negated = get_option(rest) do
-      option = if Keyword.has_key?(switches, negated) and value == nil do
-        negated
-      else
-        get_option(option)
-      end
-      {:negated, option}
-    else
+  defp get_negated("no-" <> rest = original, switches) do
+    cond do
+      (negated = get_option(rest)) && :boolean in List.wrap(switches[negated]) ->
+        {:negated, negated}
+      option = get_option(original) ->
+        {:default, option}
+      true ->
        :unknown
    end
  end

-  defp get_negated(rest, _value, _switches) do
+  defp get_negated(rest, _switches) do
    if option = get_option(rest) do
      {:default, option}
    else
@@ -60,40 +60,70 @@ defmodule Path do
  def absname(path, relative_to) do
    path = IO.chardata_to_string(path)
    case type(path) do
-      :relative -> join(relative_to, path)
-      :absolute ->
-        cond do
-          path == "/" ->
-            path
-          :binary.last(path) == ?/ ->
-            binary_part(path, 0, byte_size(path) - 1)
-          true ->
-            path
-        end
+      :relative -> absname_join(relative_to, path)
+      :absolute -> absname_join([path])
      :volumerelative ->
        relative_to = IO.chardata_to_string(relative_to)
        absname_vr(split(path), split(relative_to), relative_to)
    end
  end

-  ## Absolute path on current drive
+  # Absolute path on current drive
  defp absname_vr(["/"|rest], [volume|_], _relative),
-    do: join([volume|rest])
+    do: absname_join([volume|rest])

-  ## Relative to current directory on current drive.
+  # Relative to current directory on current drive.
  defp absname_vr([<<x, ?:>>|rest], [<<x, _ :: binary>>|_], relative),
-    do: absname(join(rest), relative)
+    do: absname(absname_join(rest), relative)

-  ## Relative to current directory on another drive.
+  # Relative to current directory on another drive.
  defp absname_vr([<<x, ?:>>|name], _, _relative) do
    cwd =
      case :file.get_cwd([x, ?:]) do
        {:ok, dir}  -> IO.chardata_to_string(dir)
        {:error, _} -> <<x, ?:, ?/>>
      end
-    absname(join(name), cwd)
+    absname(absname_join(name), cwd)
  end

+  # Joins a list
+  defp absname_join([name1, name2|rest]), do:
+    absname_join([absname_join(name1, name2)|rest])
+  defp absname_join([name]), do:
+    do_absname_join(IO.chardata_to_string(name), <<>>, [], major_os_type())
+
+  # Joins two paths
+  defp absname_join(left, right),
+    do: do_absname_join(IO.chardata_to_string(left), relative(right), [], major_os_type())
+
+  defp do_absname_join(<<uc_letter, ?:, rest :: binary>>, relativename, [], :win32) when uc_letter in ?A..?Z, do:
+    do_absname_join(rest, relativename, [?:, uc_letter+?a-?A], :win32)
+  defp do_absname_join(<<?\\, rest :: binary>>, relativename, result, :win32), do:
+    do_absname_join(<<?/, rest :: binary>>, relativename, result, :win32)
+  defp do_absname_join(<<?/, rest :: binary>>, relativename, [?., ?/|result], os_type), do:
+    do_absname_join(rest, relativename, [?/|result], os_type)
+  defp do_absname_join(<<?/, rest :: binary>>, relativename, [?/|result], os_type), do:
+    do_absname_join(rest, relativename, [?/|result], os_type)
+  defp do_absname_join(<<>>, <<>>, result, os_type), do:
+    IO.iodata_to_binary(reverse_maybe_remove_dirsep(result, os_type))
+  defp do_absname_join(<<>>, relativename, [?:|rest], :win32), do:
+    do_absname_join(relativename, <<>>, [?:|rest], :win32)
+  defp do_absname_join(<<>>, relativename, [?/|result], os_type), do:
+    do_absname_join(relativename, <<>>, [?/|result], os_type)
+  defp do_absname_join(<<>>, relativename, result, os_type), do:
+    do_absname_join(relativename, <<>>, [?/|result], os_type)
+  defp do_absname_join(<<char, rest :: binary>>, relativename, result, os_type), do:
+    do_absname_join(rest, relativename, [char|result], os_type)
+
+  defp reverse_maybe_remove_dirsep([?/, ?:, letter], :win32), do:
+    [letter, ?:, ?/]
+  defp reverse_maybe_remove_dirsep([?/], _), do:
+    [?/]
+  defp reverse_maybe_remove_dirsep([?/|name], _), do:
+    :lists.reverse(name)
+  defp reverse_maybe_remove_dirsep(name, _), do:
+    :lists.reverse(name)
+
  @doc """
  Converts the path to an absolute one and expands
  any `.` and `..` characters and a leading `~`.
@@ -106,7 +136,7 @@ defmodule Path do
  """
  @spec expand(t) :: binary
  def expand(path) do
-    normalize absname(expand_home(path), System.cwd!)
+    expand_dot absname(expand_home(path), System.cwd!)
  end

  @doc """
@@ -133,7 +163,7 @@ defmodule Path do
  """
  @spec expand(t, t) :: binary
  def expand(path, relative_to) do
-    normalize absname(absname(expand_home(path), expand_home(relative_to)), System.cwd!)
+    expand_dot absname(absname(expand_home(path), expand_home(relative_to)), System.cwd!)
  end

  @doc """
@@ -157,10 +187,7 @@ defmodule Path do
  """
  @spec type(t) :: :absolute | :relative | :volumerelative
  def type(name) when is_list(name) or is_binary(name) do
-    case :os.type() do
-      {:win32, _} -> win32_pathtype(name)
-      _             -> unix_pathtype(name)
-    end |> elem(0)
+    pathtype(name, major_os_type) |> elem(0)
  end

  @doc """
@@ -182,10 +209,20 @@ defmodule Path do
  """
  @spec relative(t) :: binary
  def relative(name) do
-    case :os.type() do
-      {:win32, _} -> win32_pathtype(name)
+    relative(name, major_os_type())
+  end
+
+  defp relative(name, os_type) do
+    pathtype(name, os_type)
+    |> elem(1)
+    |> IO.chardata_to_string
+  end
+
+  defp pathtype(name, os_type) do
+    case os_type do
+      :win32 -> win32_pathtype(name)
      _      -> unix_pathtype(name)
-    end |> elem(1) |> IO.chardata_to_string
+    end
  end

  defp unix_pathtype(<<?/, relative :: binary>>), do:
@@ -390,7 +427,7 @@ defmodule Path do
  end

  @doc """
-  Returns a string with one or more path components joined by the path separator.
+  Joins a list of strings.

  This function should be used to convert a list of strings to a path.
  Note that any trailing slash is removed on join.
@@ -411,11 +448,14 @@ defmodule Path do
  def join([name1, name2|rest]), do:
    join([join(name1, name2)|rest])
  def join([name]), do:
-    do_join(IO.chardata_to_string(name), <<>>, [], major_os_type())
+    name

  @doc """
  Joins two paths.

+  The right path will always be expanded to its relative format
+  and any trailing slash is removed on join.
+
  ## Examples

      iex> Path.join("foo", "bar")
@@ -423,44 +463,34 @@ defmodule Path do

  """
  @spec join(t, t) :: binary
-  def join(left, right),
-    do: do_join(IO.chardata_to_string(left), relative(right), [], major_os_type())
-
-  defp major_os_type do
-    :os.type |> elem(0)
+  def join(left, right) do
+    left    = IO.chardata_to_string(left)
+    os_type = major_os_type()
+    do_join(left, right, os_type) |> remove_dirsep(os_type)
  end

-  defp do_join(<<uc_letter, ?:, rest :: binary>>, relativename, [], :win32) when uc_letter in ?A..?Z, do:
-    do_join(rest, relativename, [?:, uc_letter+?a-?A], :win32)
-  defp do_join(<<?\\, rest :: binary>>, relativename, result, :win32), do:
-    do_join(<<?/, rest :: binary>>, relativename, result, :win32)
-  defp do_join(<<?/, rest :: binary>>, relativename, [?., ?/|result], os_type), do:
-    do_join(rest, relativename, [?/|result], os_type)
-  defp do_join(<<?/, rest :: binary>>, relativename, [?/|result], os_type), do:
-    do_join(rest, relativename, [?/|result], os_type)
-  defp do_join(<<>>, <<>>, result, os_type), do:
-    IO.iodata_to_binary(maybe_remove_dirsep(result, os_type))
-  defp do_join(<<>>, relativename, [?:|rest], :win32), do:
-    do_join(relativename, <<>>, [?:|rest], :win32)
-  defp do_join(<<>>, relativename, [?/|result], os_type), do:
-    do_join(relativename, <<>>, [?/|result], os_type)
-  defp do_join(<<>>, relativename, result, os_type), do:
-    do_join(relativename, <<>>, [?/|result], os_type)
-  defp do_join(<<char, rest :: binary>>, relativename, result, os_type), do:
-    do_join(rest, relativename, [char|result], os_type)
+  defp do_join("", right, os_type),   do: relative(right, os_type)
+  defp do_join(left, "", _os_type),   do: left
+  defp do_join(left, right, os_type), do: remove_dirsep(left, os_type) <> "/" <> relative(right, os_type)

-  defp maybe_remove_dirsep([?/, ?:, letter], :win32), do:
-    [letter, ?:, ?/]
-  defp maybe_remove_dirsep([?/], _), do:
-    [?/]
-  defp maybe_remove_dirsep([?/|name], _), do:
-    :lists.reverse(name)
-  defp maybe_remove_dirsep(name, _), do:
-    :lists.reverse(name)
+  defp remove_dirsep("", _os_type), do: ""
+  defp remove_dirsep(bin, os_type) do
+    last = :binary.last(bin)
+    if last == ?/ or (last == ?\\ and os_type == :win32) do
+      binary_part(bin, 0, byte_size(bin) - 1)
+    else
+      bin
+    end
+  end

-  @doc """
-  Returns a list with the path split by the path separator.
-  If an empty string is given, returns the root path.
+  @doc ~S"""
+  Splits the path into a list at the path separator.
+
+  If an empty string is given, returns an empty list.
+
+  On Windows, path is split on both "\" and "/" separators
+  and the driver letter, if there is one, is always returned
+  in lowercase.

  ## Examples

@@ -486,6 +516,11 @@ defmodule Path do
  defmodule Wildcard do
    @moduledoc false

+    def read_link_info(file) do
+      call({:read_link_info, file})
+    end
+
+    # For compatibility with buggy Erlang 17.1.
    def read_file_info(file) do
      call({:read_link_info, file})
    end
@@ -558,7 +593,7 @@ defmodule Path do
    |> Enum.map(&IO.chardata_to_string/1)
  end

-  # Normalize the given path by expanding "..", "." and "~".
+  # expand_dot the given path by expanding "..", "." and "~".

  defp chardata_to_list(chardata) do
    case :unicode.characters_to_list(chardata) do
@@ -575,34 +610,51 @@ defmodule Path do

  defp expand_home(type) do
    case IO.chardata_to_string(type) do
-      "~" <> rest -> System.user_home! <> rest
+      "~" <> rest -> resolve_home(rest)
      rest        -> rest
    end
  end

-  defp normalize(path), do: normalize(split(path), [])
+  defp resolve_home(""), do: System.user_home!

-  defp normalize([".."|t], ["/"|_] = acc) do
-    normalize t, acc
+  defp resolve_home(rest) do
+    case {rest, major_os_type} do
+      {"\\" <> _, :win32} ->
+        System.user_home! <> rest
+      {"/" <> _, _} ->
+        System.user_home! <> rest
+      _ -> rest
+    end
  end

-  defp normalize([".."|t], [<<letter, ?:, ?/>>|_] = acc) when letter in ?a..?z do
-    normalize t, acc
+  defp expand_dot(<<"/../", rest::binary>>),
+    do: expand_dot("/" <> rest)
+  defp expand_dot(<<letter, ":/../", rest::binary>>) when letter in ?a..?z,
+    do: expand_dot(<<letter, ":/", rest::binary>>)
+  defp expand_dot("/.."),
+    do: "/"
+  defp expand_dot(<<letter, ":/..">>) when letter in ?a..?z,
+    do: expand_dot(<<letter, ":/">>)
+  defp expand_dot(path),
+    do: expand_dot(:binary.split(path, "/", [:global]), [])
+
+  defp expand_dot([".."|t], [_, _|acc]) do
+    expand_dot t, acc
  end

-  defp normalize([".."|t], [_|acc]) do
-    normalize t, acc
+  defp expand_dot(["."|t], acc) do
+    expand_dot t, acc
  end

-  defp normalize(["."|t], acc) do
-    normalize t, acc
+  defp expand_dot([h|t], acc) do
+    expand_dot t, ["/", h|acc]
  end

-  defp normalize([h|t], acc) do
-    normalize t, [h|acc]
+  defp expand_dot([], ["/"|acc]) do
+    IO.iodata_to_binary(:lists.reverse(acc))
  end

-  defp normalize([], acc) do
-    join :lists.reverse(acc)
+  defp major_os_type do
+    :os.type |> elem(0)
  end
 end
@@ -5,6 +5,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#open_port-2.
+
+  Inlined by the compiler.
  """
  def open(name, settings) do
    :erlang.open_port(name, settings)
@@ -12,6 +14,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#port_close-1.
+
+  Inlined by the compiler.
  """
  def close(port) do
    :erlang.port_close(port)
@@ -19,6 +23,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#port_command-2.
+
+  Inlined by the compiler.
  """
  def command(port, data, options \\ []) do
    :erlang.port_command(port, data, options)
@@ -26,6 +32,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#port_connect-2.
+
+  Inlined by the compiler.
  """
  def connect(port, pid) do
    :erlang.port_connect(port, pid)
@@ -33,6 +41,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#port_control-3.
+
+  Inlined by the compiler.
  """
  def control(port, operation, data) do
    :erlang.port_control(port, operation, data)
@@ -40,6 +50,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#port_call-3.
+
+  Inlined by the compiler.
  """
  def call(port, operation, data) do
    :erlang.port_call(port, operation, data)
@@ -47,6 +59,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#port_info-1.
+
+  Inlined by the compiler.
  """
  def info(port) do
    :erlang.port_info(port)
@@ -54,6 +68,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#port_info-2.
+
+  Inlined by the compiler.
  """
  def info(port, item) do
    :erlang.port_info(port, item)
@@ -61,6 +77,8 @@ defmodule Port do

  @doc """
  See http://www.erlang.org/doc/man/erlang.html#ports-0.
+
+  Inlined by the compiler.
  """
  def list do
    :erlang.ports
@@ -34,7 +34,7 @@ defmodule Process do
  end

  @doc """
-  Returns the value for the given key.
+  Returns the value for the given `key`.
  """
  @spec get(term) :: term
  @spec get(term, default :: term) :: term
@@ -64,7 +64,7 @@ defmodule Process do
  end

  @doc """
-  Deletes the given key from the dictionary.
+  Deletes the given `key` from the dictionary.
  """
  @spec delete(term) :: term | nil
  def delete(key) do
@@ -79,11 +79,11 @@ defmodule Process do
    1. If pid is not trapping exits, pid will exit with the given reason.

    2. If pid is trapping exits, the exit signal is transformed into a message
-       {:EXIT, from, reason} and delivered to the message queue of pid.
+       `{:EXIT, from, reason}` and delivered to the message queue of pid.

    3. If reason is the atom `:normal`, pid will not exit. If it is trapping
-       exits, the exit signal is transformed into a message {:EXIT, from,
-       :normal} and delivered to its message queue.
+       exits, the exit signal is transformed into a message `{:EXIT, from,
+       :normal}` and delivered to its message queue.

    4. If reason is the atom `:kill`, that is if `exit(pid, :kill)` is called,
       an untrappable exit signal is sent to pid which will unconditionally
@@ -129,10 +129,10 @@ defmodule Process do
  end

  @doc """
-  Sends `msg` to `dest` after `time` millisecons.
+  Sends `msg` to `dest` after `time` milliseconds.

-  If `dest` is a pid, it has to be a pid of a local process, dead or alive.
-  If `dest` is an atom, it is supposed to be the name of a registered process
+  If `dest` is a pid, it must be the pid of a local process, dead or alive.
+  If `dest` is an atom, it must be the name of a registered process
  which is looked up at the time of delivery. No error is given if the name does
  not refer to a process.

@@ -208,8 +208,8 @@ defmodule Process do
  end

  @doc """
-  If monitor_ref is a reference which the calling process
-  obtained by calling monitor/1, this monitoring is turned off.
+  If `monitor_ref` is a reference which the calling process
+  obtained by calling `monitor/1`, this monitoring is turned off.
  If the monitoring is already turned off, nothing happens.

  See http://www.erlang.org/doc/man/erlang.html#demonitor-2 for more info.
@@ -227,7 +227,7 @@ defmodule Process do
  processes currently existing on the local node.

  Note that a process that is exiting, exists but is not alive, i.e.,
-  alive?/1 will return false for a process that is exiting,
+  `alive?/1` will return `false` for a process that is exiting,
  but its process identifier will be part of the result returned.

  See http://www.erlang.org/doc/man/erlang.html#processes-0 for more info.
@@ -252,7 +252,7 @@ defmodule Process do

  @doc """
  Removes the link, if there is one, between the calling process and
-  the process or port referred to by `pid`. Returns true and does not
+  the process or port referred to by `pid`. Returns `true` and does not
  fail, even if there is no link or `id` does not exist

  See http://www.erlang.org/doc/man/erlang.html#unlink-1 for more info.
@@ -265,13 +265,13 @@ defmodule Process do
  end

  @doc """
-  Associates the name with a pid or a port identifier. name, which must
+  Associates the name with a pid or a port identifier. `name`, which must
  be an atom, can be used instead of the pid / port identifier with the
  `Kernel.send/2` function.

  `Process.register/2` will fail with `ArgumentError` if the pid supplied
  is no longer alive, (check with `alive?/1`) or if the name is
-  already registered (check with `registered?/1`).
+  already registered (check with `whereis/1`).
  """
  @spec register(pid | port, atom) :: true
  def register(pid, name) when not name in [nil, false, true] do
@@ -290,7 +290,7 @@ defmodule Process do

  @doc """
  Returns the pid or port identifier with the registered name.
-  Returns nil if the name is not registered.
+  Returns `nil` if the name is not registered.

  See http://www.erlang.org/doc/man/erlang.html#whereis-1 for more info.
  """
@@ -309,7 +309,7 @@ defmodule Process do

  @doc """
  Sets the group leader of `pid` to `leader`. Typically, this is used when a processes
-  started from a certain shell should have another group leader than `:init`.
+  started from a certain shell should have a group leader other than `:init`.
  """
  @spec group_leader(pid, leader :: pid) :: true
  def group_leader(pid, leader) do
@@ -317,7 +317,7 @@ defmodule Process do
  end

  @doc """
-  Returns a list of names which have been registered using register/2.
+  Returns a list of names which have been registered using `register/2`.
  """
  @spec registered :: [atom]
  def registered do
@@ -339,19 +339,19 @@ defmodule Process do
  end

  @doc """
-  Sets certain flags for the process Pid, in the same manner as flag/2.
-  Returns the old value of the flag. The allowed values for Flag are
-  only a subset of those allowed in flag/2, namely: save_calls.
+  Sets certain flags for the process `pid`, in the same manner as `flag/2`.
+  Returns the old value of the flag. The allowed values for `flag` are
+  only a subset of those allowed in `flag/2`, namely: `save_calls`.

  See http://www.erlang.org/doc/man/erlang.html#process_flag-3 for more info.
  """
-  @spec flag(pid, process_flag, term) :: term
+  @spec flag(pid, :save_calls, non_neg_integer) :: non_neg_integer
  def flag(pid, flag, value) do
    :erlang.process_flag(pid, flag, value)
  end

  @doc """
-  Returns information about the process identified by pid or nil if the process
+  Returns information about the process identified by `pid` or `nil` if the process
  is not alive.
  Use this only for debugging information.

@@ -363,8 +363,8 @@ defmodule Process do
  end

  @doc """
-  Returns information about the process identified by pid
-  or nil if the process is not alive.
+  Returns information about the process identified by `pid`
+  or `nil` if the process is not alive.

  See http://www.erlang.org/doc/man/erlang.html#process_info-2 for more info.
  """
@@ -19,11 +19,12 @@ defmodule Protocol do
  defmacro def({name, _, args}) when is_atom(name) and is_list(args) do
    arity = length(args)

-    type_args = for _ <- :lists.seq(2, arity), do: quote(do: term)
+    type_args = :lists.map(fn _ -> quote(do: term) end,
+                           :lists.seq(2, arity))
    type_args = [quote(do: t) | type_args]

-    call_args = for i <- :lists.seq(2, arity),
-                  do: {String.to_atom(<<?x, i + 64>>), [], __MODULE__}
+    call_args = :lists.map(fn i -> {String.to_atom(<<?x, i + 64>>), [], __MODULE__} end,
+                           :lists.seq(2, arity))
    call_args = [quote(do: t) | call_args]

    quote do
@@ -85,11 +86,13 @@ defmodule Protocol do
  Returns `:ok` if so, otherwise raises ArgumentError.
  """
  @spec assert_impl!(module, module) :: :ok | no_return
-  def assert_impl!(protocol, impl) do
-    assert_impl!(protocol, impl, "")
+  def assert_impl!(protocol, base) do
+    assert_impl!(protocol, base, "")
  end

-  defp assert_impl!(protocol, impl, extra) do
+  defp assert_impl!(protocol, base, extra) do
+    impl = Module.concat(protocol, base)
+
    case Code.ensure_compiled(impl) do
      {:module, ^impl} -> :ok
      _ -> raise ArgumentError,
@@ -287,7 +290,7 @@ defmodule Protocol do

  defp beam_file(module) when is_atom(module) do
    case :code.which(module) do
-      :non_existing -> module
+      atom when is_atom(atom) -> module
      file -> file
    end
  end
@@ -426,7 +429,7 @@ defmodule Protocol do

  defp after_defprotocol do
    quote bind_quoted: [builtin: builtin] do
-      @spec impl_for(term) :: module | nil
+      @spec impl_for(term) :: atom() | nil
      Kernel.def impl_for(data)

      # Define the implementation for structs.
@@ -438,7 +441,7 @@ defmodule Protocol do
      end

      # Define the implementation for builtins.
-      for {guard, mod} <- builtin do
+      :lists.foreach(fn {guard, mod} ->
        target = Module.concat(__MODULE__, mod)

        Kernel.def impl_for(data) when :erlang.unquote(guard)(data) do
@@ -447,9 +450,9 @@ defmodule Protocol do
            false -> any_impl_for
          end
        end
-      end
+      end, builtin)

-      @spec impl_for!(term) :: module | no_return
+      @spec impl_for!(term) :: atom() | no_return()
      Kernel.def impl_for!(data) do
        impl_for(data) || raise(Protocol.UndefinedError, protocol: __MODULE__, value: data)
      end
@@ -494,12 +497,19 @@ defmodule Protocol do
      @protocol [fallback_to_any: !!@fallback_to_any, consolidated: false]

      @doc false
-      @spec __protocol__(atom) :: term
+      @spec __protocol__(:name) :: __MODULE__
+      @spec __protocol__(:functions) :: unquote(Protocol.__functions_spec__(@functions))
      Kernel.def __protocol__(:name), do: __MODULE__
      Kernel.def __protocol__(:functions), do: unquote(:lists.sort(@functions))
    end
  end

+  @doc false
+  def __functions_spec__([]),
+    do: []
+  def __functions_spec__([h|t]),
+    do: [:lists.foldl(&{:|, [], [&1, &2]}, h, t), quote(do: ...)]
+
  @doc false
  def __impl__(protocol, opts) do
    do_defimpl(protocol, :lists.keysort(1, opts))
@@ -510,6 +520,20 @@ defmodule Protocol do
  end

  defp do_defimpl(protocol, [do: block, for: for]) do
+    # Unquote the implementation just later
+    # when all variables will already be injected
+    # into the module body.
+    __impl__ =
+      quote unquote: false do
+        @doc false
+        @spec __impl__(:for) :: unquote(for)
+        @spec __impl__(:target) :: __MODULE__
+        @spec __impl__(:protocol) :: unquote(protocol)
+        def __impl__(:for),      do: unquote(for)
+        def __impl__(:target),   do: __MODULE__
+        def __impl__(:protocol), do: unquote(protocol)
+      end
+
    quote do
      protocol = unquote(protocol)
      for      = unquote(for)
@@ -527,11 +551,7 @@ defmodule Protocol do
        Module.register_attribute(__MODULE__, :impl, persist: true)
        @impl [protocol: @protocol, for: @for]

-        @doc false
-        @spec __impl__(atom) :: term
-        def __impl__(:target),   do: __MODULE__
-        def __impl__(:protocol), do: @protocol
-        def __impl__(:for),      do: @for
+        unquote(__impl__)
      end
    end
  end
@@ -557,14 +577,14 @@ defmodule Protocol do
  end

  defp derive(protocol, for, struct, opts, env) do
-    impl  = Module.concat(protocol, Map)
    extra = ", cannot derive #{inspect protocol} for #{inspect for}"
    assert_protocol!(protocol, extra)
-    assert_impl!(protocol, impl, extra)
+    assert_impl!(protocol, Map, extra)

    # Clean up variables from eval context
    env  = %{env | vars: [], export_vars: nil}
    args = [for, struct, opts]
+    impl = Module.concat(protocol, Map)

    :elixir_module.expand_callback(env.line, impl, :__deriving__, args, env, fn
      mod, fun, args ->
@@ -576,7 +596,9 @@ defmodule Protocol do
            @impl [protocol: unquote(protocol), for: unquote(for)]

            @doc false
-            @spec __impl__(atom) :: term
+            @spec __impl__(:target) :: unquote(impl)
+            @spec __impl__(:protocol) :: unquote(protocol)
+            @spec __impl__(:for) :: unquote(for)
            def __impl__(:target),   do: unquote(impl)
            def __impl__(:protocol), do: unquote(protocol)
            def __impl__(:for),      do: unquote(for)
@@ -588,16 +610,17 @@ defmodule Protocol do
  @doc false
  def __spec__?(module, name, arity) do
    signature = {name, arity}
-    specs     = Module.get_attribute(module, :spec)

+    specs = Module.get_attribute(module, :spec)
    found =
-      for {:spec, expr, caller} <- specs,
-          Kernel.Typespec.spec_to_signature(expr) == signature do
+      :lists.map(fn {:spec, expr, caller} ->
+        if Kernel.Typespec.spec_to_signature(expr) == signature do
          Kernel.Typespec.define_spec(:callback, expr, caller)
          true
        end
+      end, specs)

-    found != []
+    :lists.any(& &1 == true, found)
  end

  ## Helpers
@@ -2,7 +2,7 @@ defmodule Range do
  @moduledoc """
  Defines a Range.

-  A Range are represented internally as a struct. However,
+  A Range is represented internally as a struct. However,
  the most common form of creating and matching on ranges
  is via the `../2` macro, auto-imported from Kernel:

@@ -18,7 +18,8 @@ defmodule Range do

  defstruct first: nil, last: nil

-  @type t(first, last) :: %{__struct__: Range, first: first, last: last}
+  @type t :: %Range{}
+  @type t(first, last) :: %Range{first: first, last: last}

  @doc """
  Creates a new range.
@@ -4,7 +4,7 @@ defmodule Record do

  Records are simply tuples where the first element is an atom:

-      iex> Record.record? {User, "jose", 27}
+      iex> Record.is_record {User, "john", 27}
      true

  This module provides conveniences for working with records at
@@ -20,6 +20,20 @@ defmodule Record do
  The macros `defrecord/3` and `defrecordp/3` can be used to create
  records while `extract/2` can be used to extract records from Erlang
  files.
+
+  ## Types
+
+  Types can be defined for tuples with the `record/2` macro (only available
+  in typespecs). Like with the generated record macros it will expand to
+  a tuple.
+
+      defmodule MyModule do
+        require Record
+        Record.defrecord :user name: "john", age: 25
+
+        @type user :: record(:user, name: String.t, age: integer)
+        # expands to: `@type user :: {:user, String.t, integer}`
+      end
  """

  @doc """
@@ -49,12 +63,12 @@ defmodule Record do

  ## Examples

-      iex> record = {User, "jose", 27}
-      iex> Record.record?(record, User)
+      iex> record = {User, "john", 27}
+      iex> Record.is_record(record, User)
      true

  """
-  defmacro record?(data, kind) do
+  defmacro is_record(data, kind) do
    case Macro.Env.in_guard?(__CALLER__) do
      true ->
        quote do
@@ -77,15 +91,15 @@ defmodule Record do

  ## Examples

-      iex> record = {User, "jose", 27}
-      iex> Record.record?(record)
+      iex> record = {User, "john", 27}
+      iex> Record.is_record(record)
      true
      iex> tuple = {}
-      iex> Record.record?(tuple)
+      iex> Record.is_record(tuple)
      false

  """
-  defmacro record?(data) do
+  defmacro is_record(data) do
    case Macro.Env.in_guard?(__CALLER__) do
      true ->
        quote do
@@ -111,26 +125,31 @@ defmodule Record do
  ## Examples

      defmodule User do
-        Record.defrecord :user, [name: "José", age: "25"]
+        require Record
+        Record.defrecord :user, [name: "meg", age: "25"]
      end

  In the example above, a set of macros named `user` but with different
  arities will be defined to manipulate the underlying record:

      # To create records
-      user()        #=> {:user, "José", 25}
-      user(age: 26) #=> {:user, "José", 26}
+      record = user()        #=> {:user, "meg", 25}
+      record = user(age: 26) #=> {:user, "meg", 26}

      # To get a field from the record
-      user(record, :name) #=> "José"
+      user(record, :name) #=> "meg"

      # To update the record
-      user(record, age: 26) #=> {:user, "José", 26}
+      user(record, age: 26) #=> {:user, "meg", 26}
+
+      # Convert a record to a keyword list
+      user(record) #=> [name: "meg", age: 26]

  By default, Elixir uses the record name as the first element of
  the tuple (the tag). But it can be changed to something else:

      defmodule User do
+        require Record
        Record.defrecord :user, User, name: nil
      end

@@ -141,7 +160,7 @@ defmodule Record do
  defmacro defrecord(name, tag \\ nil, kv) do
    quote bind_quoted: [name: name, tag: tag, kv: kv] do
      tag = tag || name
-      fields = Macro.escape Record.__fields__(:defrecord, kv)
+      fields = Record.__fields__(:defrecord, kv)

      defmacro(unquote(name)(args \\ [])) do
        Record.__access__(unquote(tag), unquote(fields), args, __CALLER__)
@@ -159,7 +178,7 @@ defmodule Record do
  defmacro defrecordp(name, tag \\ nil, kv) do
    quote bind_quoted: [name: name, tag: tag, kv: kv] do
      tag = tag || name
-      fields = Macro.escape Record.__fields__(:defrecordp, kv)
+      fields = Record.__fields__(:defrecordp, kv)

      defmacrop(unquote(name)(args \\ [])) do
        Record.__access__(unquote(tag), unquote(fields), args, __CALLER__)
@@ -175,9 +194,19 @@ defmodule Record do
  @doc false
  def __fields__(type, fields) do
    :lists.map(fn
-      { key, _ } = pair when is_atom(key) -> pair
-      key when is_atom(key) -> { key, nil }
-      other -> raise ArgumentError, "#{type} fields must be atoms, got: #{inspect other}"
+      {key, val} when is_atom(key) ->
+        try do
+          Macro.escape(val)
+        rescue
+          e in [ArgumentError] ->
+            raise ArgumentError, "invalid value for record field #{key}, " <> Exception.message(e)
+        else
+          val -> {key, val}
+        end
+      key when is_atom(key) ->
+        {key, nil}
+      other ->
+        raise ArgumentError, "#{type} fields must be atoms, got: #{inspect other}"
    end, fields)
  end

@@ -190,8 +219,15 @@ defmodule Record do
      Keyword.keyword?(args) ->
        create(atom, fields, args, caller)
      true ->
-        msg = "expected arguments to be a compile time atom or keywords, got: #{Macro.to_string args}"
-        raise ArgumentError, msg
+        case Macro.expand(args, caller) do
+          {:{}, _, [^atom|list]} when length(list) == length(fields) ->
+            record = List.to_tuple([atom|list])
+            Macro.escape(Record.__keyword__(atom, fields, record))
+          {^atom, arg} when length(fields) == 1 ->
+            Macro.escape(Record.__keyword__(atom, fields, {atom, arg}))
+          _ ->
+            quote do: Record.__keyword__(unquote(atom), unquote(fields), unquote(args))
+        end
    end
  end

@@ -279,4 +315,21 @@ defmodule Record do
  defp find_index([{k, _}|_], k, i), do: i + 2
  defp find_index([{_, _}|t], k, i), do: find_index(t, k, i + 1)
  defp find_index([], _k, _i), do: nil
+
+  # Returns a keyword list of the record
+  @doc false
+  def __keyword__(atom, fields, record) do
+    if is_record(record, atom) do
+      [_tag|values] = Tuple.to_list(record)
+      join_keyword(fields, values, [])
+    else
+      msg = "expected argument to be a literal atom, literal keyword or a #{inspect atom} record, got runtime: #{inspect record}"
+      raise ArgumentError, msg
+    end
+  end
+
+  defp join_keyword([{field, _default}|fields], [value|values], acc),
+    do: join_keyword(fields, values, [{field, value}| acc])
+  defp join_keyword([], [], acc),
+    do: :lists.reverse(acc)
 end
@@ -45,10 +45,11 @@ defmodule Record.Extractor do
  end

  # Read a file and return its abstract syntax form that also
-  # includes record and other preprocessor modules. This is done
-  # by using Erlang's epp_dodger.
+  # includes record but with macros and other attributes expanded,
+  # such as `-include(...)` and `-include_lib(...)`. This is done
+  # by using Erlang's epp.
  defp read_file(file) do
-    case :epp_dodger.quick_parse_file(file) do
+    case :epp.parse_file(file, []) do
      {:ok, form} ->
        form
      other ->
@@ -22,8 +22,9 @@ defmodule Regex do

  The modifiers available when creating a Regex are:

-    * `unicode` (u) - enables unicode specific patterns like `\p`; it expects
-      valid unicode strings to be given on match
+    * `unicode` (u) - enables unicode specific patterns like `\p` and changes
+      modifiers like `\w`, `\W`, `\s` and friends to also match on unicode.
+      It expects valid unicode strings to be given on match

    * `caseless` (i) - add case insensitivity

@@ -75,7 +76,9 @@ defmodule Regex do

  """

-  defstruct re_pattern: nil :: term, source: "" :: binary, opts: "" :: binary
+  defstruct re_pattern: nil, source: "", opts: ""
+
+  @type t :: %__MODULE__{re_pattern: term, source: binary, opts: binary}

  defmodule CompileError do
    defexception message: "regex could not be compiled"
@@ -104,7 +107,7 @@ defmodule Regex do
  def compile(source, options \\ "")

  def compile(source, options) when is_binary(options) do
-    case translate_options(options) do
+    case translate_options(options, []) do
      {:error, rest} ->
        {:error, {:invalid_option, rest}}

@@ -130,6 +133,7 @@ defmodule Regex do
  Compiles the regular expression according to the given options.
  Fails with `Regex.CompileError` if the regex cannot be compiled.
  """
+  @spec compile(binary, binary | [term]) :: t
  def compile!(source, options \\ "") do
    case compile(source, options) do
      {:ok, regex} -> regex
@@ -149,6 +153,7 @@ defmodule Regex do
      false

  """
+  @spec match?(t, String.t) :: boolean
  def match?(%Regex{re_pattern: compiled}, string) when is_binary(string) do
    :re.run(string, compiled, [{:capture, :none}]) == :match
  end
@@ -165,6 +170,8 @@ defmodule Regex do
      false

  """
+  @spec regex?(t) :: true
+  @spec regex?(any) :: false
  def regex?(%Regex{}), do: true
  def regex?(_), do: false

@@ -190,6 +197,7 @@ defmodule Regex do
      [{2,2},{3,1}]

  """
+  @spec run(t, binary, [term]) :: nil | [binary] | [{integer, integer}]
  def run(regex, string, options \\ [])

  def run(%Regex{re_pattern: compiled}, string, options) when is_binary(string) do
@@ -220,6 +228,7 @@ defmodule Regex do
      nil

  """
+  @spec named_captures(t, String.t, [term]) :: map | nil
  def named_captures(regex, string, options \\ []) when is_binary(string) do
    names = names(regex)
    options = Keyword.put(options, :capture, names)
@@ -230,6 +239,7 @@ defmodule Regex do
  @doc """
  Returns the underlying `re_pattern` in the regular expression.
  """
+  @spec re_pattern(t) :: term
  def re_pattern(%Regex{re_pattern: compiled}) do
    compiled
  end
@@ -243,6 +253,7 @@ defmodule Regex do
      "foo"

  """
+  @spec source(t) :: String.t
  def source(%Regex{source: source}) do
    source
  end
@@ -256,6 +267,7 @@ defmodule Regex do
      "m"

  """
+  @spec opts(t) :: String.t
  def opts(%Regex{opts: opts}) do
    opts
  end
@@ -269,6 +281,7 @@ defmodule Regex do
      ["foo"]

  """
+  @spec names(t) :: [String.t]
  def names(%Regex{re_pattern: re_pattern}) do
    {:namelist, names} = :re.inspect(re_pattern, :namelist)
    names
@@ -298,6 +311,7 @@ defmodule Regex do
      []

  """
+  @spec scan(t, String.t, [term]) :: [[String.t]]
  def scan(regex, string, options \\ [])

  def scan(%Regex{re_pattern: compiled}, string, options) when is_binary(string) do
@@ -318,12 +332,17 @@ defmodule Regex do
  ## Options

    * `:parts` - when specified, splits the string into the given number of
-      parts. If not specified, `:parts` is defaulted to `:infinity`, which will
+      parts. If not specified, `:parts` defaults to `:infinity`, which will
      split the string into the maximum number of parts possible based on the
      given pattern.

    * `:trim` - when true, remove blank strings from the result.

+    * `:on` - specifies which captures and order to split the string
+      on. Check the moduledoc for `Regex` to see the possible capture
+      values. Defaults to `:first` which means captures inside the
+      Regex does not affect the split result.
+
  ## Examples

      iex> Regex.split(~r/-/, "a-b-c")
@@ -338,36 +357,70 @@ defmodule Regex do
      iex> Regex.split(~r//, "abc")
      ["a", "b", "c", ""]

-      iex> Regex.split(~r//, "abc", trim: true)
-      ["a", "b", "c"]
+      iex> Regex.split(~r/a(?<second>b)c/, "abc")
+      ["", ""]
+
+      iex> Regex.split(~r/a(?<second>b)c/, "abc", on: [:second])
+      ["a", "c"]

  """
-
+  @spec split(t, String.t, [term]) :: [String.t]
  def split(regex, string, options \\ [])

-  def split(%Regex{re_pattern: compiled}, string, options) when is_binary(string) do
-    parts  = Keyword.get(options, :parts, :infinity)
-    opts   = [return: :binary, parts: zero_to_infinity(parts)]
-    splits = :re.split(string, compiled, opts)
+  def split(%Regex{}, "", _opts), do: [""]

-    if Keyword.get(options, :trim, false) do
-      for split <- splits, split != "", do: split
+  def split(%Regex{re_pattern: compiled}, string, opts) when is_binary(string) do
+    on = Keyword.get(opts, :on, :first)
+    case :re.run(string, compiled, [:global, capture: on]) do
+      {:match, matches} ->
+        do_split(matches, string, 0,
+                 parts_to_index(Keyword.get(opts, :parts, :infinity)),
+                 Keyword.get(opts, :trim, false))
+      :match ->
+        [string]
+      :nomatch ->
+        [string]
+    end
+  end
+
+  defp parts_to_index(:infinity),                      do: 0
+  defp parts_to_index(n) when is_integer(n) and n > 0, do: n
+
+  defp do_split(_, string, offset, _counter, true) when byte_size(string) <= offset,
+    do: []
+
+  defp do_split(_, string, offset, 1, _trim),
+    do: [binary_part(string, offset, byte_size(string) - offset)]
+
+  defp do_split([], string, offset, _counter, _trim),
+    do: [binary_part(string, offset, byte_size(string) - offset)]
+
+  defp do_split([[{pos, _}|h]|t], string, offset, counter, trim) when pos - offset < 0,
+    do: do_split([h|t], string, offset, counter, trim)
+
+  defp do_split([[]|t], string, offset, counter, trim),
+    do: do_split(t, string, offset, counter, trim)
+
+  defp do_split([[{pos, length}|h]|t], string, offset, counter, trim) do
+    new_offset = pos + length
+    keep = pos - offset
+
+    if keep == 0 and (length == 0 or trim) do
+      do_split([h|t], string, new_offset, counter, trim)
    else
-      splits
+      <<_::binary-size(offset), part::binary-size(keep), _::binary>> = string
+      [part|do_split([h|t], string, new_offset, counter - 1, trim)]
    end
  end

-  defp zero_to_infinity(0), do: :infinity
-  defp zero_to_infinity(n), do: n
-
  @doc ~S"""
  Receives a regex, a binary and a replacement, returns a new
  binary where the all matches are replaced by replacement.

  The replacement can be either a string or a function. The string
  is used as a replacement for every match and it allows specific
-  captures to be accessed via `\N`, where `N` is the capture. In
-  case `\0` is used, the whole match is inserted.
+  captures to be accessed via `\N` or `\g{N}`, where `N` is the
+  capture. In case `\0` is used, the whole match is inserted.

  When the replacement is a function, the function may have arity
  N where each argument maps to a capture, with the first argument
@@ -397,6 +450,7 @@ defmodule Regex do
      "[b][d]"

  """
+  @spec replace(t, String.t, String.t | (... -> String.t), [term]) :: String.t
  def replace(regex, string, replacement, options \\ [])

  def replace(regex, string, replacement, options) when is_binary(replacement) do
@@ -425,6 +479,11 @@ defmodule Regex do
  defp precompile_replacement(""),
    do: []

+  defp precompile_replacement(<<?\\, ?g, ?{, rest :: binary>>) when byte_size(rest) > 0 do
+    {ns, <<?}, rest :: binary>>} = pick_int(rest)
+    [List.to_integer(ns) | precompile_replacement(rest)]
+  end
+
  defp precompile_replacement(<<?\\, x, rest :: binary>>) when x < ?0 or x > ?9 do
    case precompile_replacement(rest) do
      [head | t] when is_binary(head) ->
@@ -471,12 +530,12 @@ defmodule Regex do

  defp apply_list(whole, string, pos, replacement, [[{mpos, _} | _] | _] = list) when mpos > pos do
    length = mpos - pos
-    <<untouched :: [size(length), binary], rest :: binary>> = string
+    <<untouched :: binary-size(length), rest :: binary>> = string
    [untouched | apply_list(whole, rest, mpos, replacement, list)]
  end

  defp apply_list(whole, string, pos, replacement, [[{mpos, length} | _] = head | tail]) when mpos == pos do
-    <<_ :: [size(length), binary], rest :: binary>> = string
+    <<_ :: size(length)-binary, rest :: binary>> = string
    new_data = apply_replace(whole, replacement, head)
    [new_data | apply_list(whole, rest, pos + length, replacement, tail)]
  end
@@ -496,7 +555,7 @@ defmodule Regex do
      cond do
        is_binary(part) ->
          part
-        part > tuple_size(indexes) ->
+        part >= tuple_size(indexes) ->
          ""
        true ->
          get_index(string, elem(indexes, part))
@@ -509,7 +568,7 @@ defmodule Regex do
  end

  defp get_index(string, {pos, len}) do
-    <<_ :: [size(pos), binary], res :: [size(len), binary], _ :: binary>> = string
+    <<_ :: size(pos)-binary, res :: size(len)-binary, _ :: binary>> = string
    res
  end

@@ -559,18 +618,13 @@ defmodule Regex do

  # Private Helpers

-  defp translate_options(<<?g, t :: binary>>) do
-    IO.write :stderr, "The /g flag for regular expressions is no longer needed\n#{Exception.format_stacktrace}"
-    translate_options(t)
-  end
-
-  defp translate_options(<<?u, t :: binary>>), do: [:unicode|translate_options(t)]
-  defp translate_options(<<?i, t :: binary>>), do: [:caseless|translate_options(t)]
-  defp translate_options(<<?x, t :: binary>>), do: [:extended|translate_options(t)]
-  defp translate_options(<<?f, t :: binary>>), do: [:firstline|translate_options(t)]
-  defp translate_options(<<?r, t :: binary>>), do: [:ungreedy|translate_options(t)]
-  defp translate_options(<<?s, t :: binary>>), do: [:dotall, {:newline, :anycrlf}|translate_options(t)]
-  defp translate_options(<<?m, t :: binary>>), do: [:multiline|translate_options(t)]
-  defp translate_options(<<>>), do: []
-  defp translate_options(rest), do: {:error, rest}
+  defp translate_options(<<?u, t :: binary>>, acc), do: translate_options(t, [:unicode, :ucp|acc])
+  defp translate_options(<<?i, t :: binary>>, acc), do: translate_options(t, [:caseless|acc])
+  defp translate_options(<<?x, t :: binary>>, acc), do: translate_options(t, [:extended|acc])
+  defp translate_options(<<?f, t :: binary>>, acc), do: translate_options(t, [:firstline|acc])
+  defp translate_options(<<?r, t :: binary>>, acc), do: translate_options(t, [:ungreedy|acc])
+  defp translate_options(<<?s, t :: binary>>, acc), do: translate_options(t, [:dotall, {:newline, :anycrlf}|acc])
+  defp translate_options(<<?m, t :: binary>>, acc), do: translate_options(t, [:multiline|acc])
+  defp translate_options(<<>>, acc), do: acc
+  defp translate_options(rest, _acc), do: {:error, rest}
 end
@@ -198,7 +198,7 @@ defmodule Set do
    if target1 == target2 do
      target1.intersection(set1, set2)
    else
-      target1.reduce(set1, {:cont, Collectable.empty(set1)}, fn v, acc ->
+      target1.reduce(set1, {:cont, target1.new}, fn v, acc ->
        {:cont, if(target2.member?(set2, v), do: target1.put(acc, v), else: acc)}
      end) |> elem(1)
    end
@@ -89,12 +89,14 @@ defmodule Stream do
  returns an anonymous function may return a struct in future releases.
  """

+  @doc false
  defstruct enum: nil, funs: [], accs: [], done: nil

  @type acc     :: any
  @type element :: any
  @type index   :: non_neg_integer
  @type default :: any
+  @type       t :: %__MODULE__{}

  # Require Stream.Reducers and its callbacks
  require Stream.Reducers, as: R
@@ -154,19 +156,23 @@ defmodule Stream do
  @spec chunk(Enumerable.t, non_neg_integer, non_neg_integer, Enumerable.t | nil) :: Enumerable.t
  def chunk(enum, n, step, pad \\ nil) when n > 0 and step > 0 do
    limit = :erlang.max(n, step)
+    if is_nil(pad) do
+      lazy enum, {[], 0}, fn(f1) -> R.chunk(n, step, limit, f1) end
+    else
      lazy enum, {[], 0},
           fn(f1) -> R.chunk(n, step, limit, f1) end,
-         fn(f1) -> &do_chunk(&1, n, pad, f1) end
+           &do_chunk(&1, n, pad, &2)
+     end
  end

-  defp do_chunk(acc(h, {buffer, count} = old, t) = acc, n, pad, f1) do
-    if nil?(pad) || count == 0 do
+  defp do_chunk(acc(_, {_, 0}, _) = acc, _, _, _) do
    {:cont, acc}
-    else
+  end
+
+  defp do_chunk(acc(h, {buffer, count} = old, t), n, pad, f1) do
    buffer = :lists.reverse(buffer) ++ Enum.take(pad, n - count)
    cont_with_acc(f1, buffer, h, old, t)
  end
-  end

  @doc """
  Chunks the `enum` by buffering elements for which `fun` returns
@@ -184,7 +190,7 @@ defmodule Stream do
  def chunk_by(enum, fun) do
    lazy enum, nil,
         fn(f1) -> R.chunk_by(fun, f1) end,
-         fn(f1) -> &do_chunk_by(&1, f1) end
+         &do_chunk_by(&1, &2)
  end

  defp do_chunk_by(acc(_, nil, _) = acc, _f1) do
@@ -336,6 +342,25 @@ defmodule Stream do
    lazy enum, fn(f1) -> R.filter_map(filter, mapper, f1) end
  end

+  @doc """
+  Creates a stream that emits a value every `n` milliseconds.
+
+  The values emitted are an increasing counter starting at `0`.
+
+  ## Examples
+
+      iex> Stream.interval(10) |> Enum.take(10)
+      [0,1,2,3,4,5,6,7,8,9]
+
+  """
+  @spec interval(non_neg_integer) :: Enumerable.t
+  def interval(n) do
+    unfold 0, fn (count) ->
+      :timer.sleep(n)
+      {count, count + 1}
+    end
+  end
+
  @doc """
  Injects the stream values into the given collectable as a side-effect.

@@ -427,7 +452,7 @@ defmodule Stream do
  """
  @spec run(Enumerable.t) :: :ok
  def run(stream) do
-    Enumerable.reduce(stream, {:cont, nil}, fn(_, _) -> {:cont, nil} end)
+    _ = Enumerable.reduce(stream, {:cont, nil}, fn(_, _) -> {:cont, nil} end)
    :ok
  end

@@ -493,11 +518,11 @@ defmodule Stream do
  @spec take(Enumerable.t, non_neg_integer) :: Enumerable.t
  def take(_enum, 0), do: %Stream{enum: []}

-  def take(enum, n) when n > 0 do
+  def take(enum, n) when n > 0 and is_integer(n) do
    lazy enum, n, fn(f1) -> R.take(f1) end
  end

-  def take(enum, n) when n < 0 do
+  def take(enum, n) when n < 0 and is_integer(n) do
    &do_take(enum, abs(n), &1, &2)
  end

@@ -561,6 +586,22 @@ defmodule Stream do
    lazy enum, fn(f1) -> R.take_while(fun, f1) end
  end

+  @doc """
+  Creates a stream that emits a single value after `n` milliseconds.
+
+  The value emitted is `0`.
+
+  ## Examples
+
+      iex> Stream.timer(10) |> Enum.to_list
+      [0]
+
+  """
+  @spec timer(non_neg_integer) :: Enumerable.t
+  def timer(n) do
+    take(interval(n), 1)
+  end
+
  @doc """
  Transforms an existing stream.

@@ -575,7 +616,7 @@ defmodule Stream do

  ## Examples

-  `Stream.transform/3` is a useful as it can be used as basis to implement
+  `Stream.transform/3` is useful as it can be used as the basis to implement
  many of the functions defined in this module. For example, we can implement
  `Stream.take(enum, n)` as follows:

@@ -616,12 +657,14 @@ defmodule Stream do
          {[], user_acc} ->
            do_transform(user_acc, user, fun, next_acc, next, inner_acc, inner)
          {list, user_acc} when is_list(list) ->
-            do_list_transform(user_acc, user, fun, next_acc, next, inner_acc, inner, &Enumerable.List.reduce(list, &1, fun))
+            do_list_transform(user_acc, user, fun, next_acc, next, inner_acc, inner,
+                              &Enumerable.List.reduce(list, &1, fun))
          {:halt, _user_acc} ->
            next.({:halt, next_acc})
            {:halted, elem(inner_acc, 1)}
          {other, user_acc} ->
-            do_other_transform(user_acc, user, fun, next_acc, next, inner_acc, inner, &Enumerable.reduce(other, &1, inner))
+            do_enum_transform(user_acc, user, fun, next_acc, next, inner_acc, inner,
+                              &Enumerable.reduce(other, &1, inner))
        end
      {reason, _} ->
        {reason, elem(inner_acc, 1)}
@@ -633,8 +676,9 @@ defmodule Stream do
      reduce.(inner_acc)
    catch
      kind, reason ->
+        stacktrace = System.stacktrace
        next.({:halt, next_acc})
-        :erlang.raise(kind, reason, :erlang.get_stacktrace)
+        :erlang.raise(kind, reason, stacktrace)
    else
      {:done, acc} ->
        do_transform(user_acc, user, fun, next_acc, next, {:cont, acc}, inner)
@@ -646,29 +690,33 @@ defmodule Stream do
    end
  end

-  defp do_other_transform(user_acc, user, fun, next_acc, next, inner_acc, inner, reduce) do
+  defp do_enum_transform(user_acc, user, fun, next_acc, next, {op, inner_acc}, inner, reduce) do
    try do
-      reduce.(inner_acc)
+      reduce.({op, [:outer|inner_acc]})
    catch
-      {:stream_transform, h} ->
-        next.({:halt, next_acc})
-        {:halted, h}
      kind, reason ->
        stacktrace = System.stacktrace
        next.({:halt, next_acc})
        :erlang.raise(kind, reason, stacktrace)
    else
-      {_, acc} ->
+      # Only take into account outer halts when the op is not halt itself.
+      # Otherwise, we were the ones wishing to halt, so we should just stop.
+      {:halted, [:outer|acc]} when op != :halt ->
        do_transform(user_acc, user, fun, next_acc, next, {:cont, acc}, inner)
-      {:suspended, acc, c} ->
-        {:suspended, acc, &do_other_transform(user_acc, user, fun, next_acc, next, &1, inner, c)}
+      {:halted, [_|acc]} ->
+        next.({:halt, next_acc})
+        {:halted, acc}
+      {:done, [_|acc]} ->
+        do_transform(user_acc, user, fun, next_acc, next, {:cont, acc}, inner)
+      {:suspended, [_|acc], c} ->
+        {:suspended, acc, &do_enum_transform(user_acc, user, fun, next_acc, next, &1, inner, c)}
    end
  end

-  defp do_transform_each(x, acc, f) do
+  defp do_transform_each(x, [:outer|acc], f) do
    case f.(x, acc) do
-      {:halt, h} -> throw({:stream_transform, h})
-      {_, _} = o -> o
+      {:halt, res} -> {:halt, [:inner|res]}
+      {op, res}    -> {op, [:outer|res]}
    end
  end

@@ -840,6 +888,15 @@ defmodule Stream do

  """
  @spec cycle(Enumerable.t) :: Enumerable.t
+  def cycle(enumerable)
+
+  def cycle(enumerable) when is_list(enumerable) do
+    unfold {enumerable, enumerable}, fn
+      {source, [h | t]}      -> {h, {source, t}}
+      {source = [h | t], []} -> {h, {source, t}}
+    end
+  end
+
  def cycle(enumerable) do
    fn acc, fun ->
      inner = &do_cycle_each(&1, &2, fun)
@@ -927,14 +984,15 @@ defmodule Stream do
  @doc """
  Emits a sequence of values for the given resource.

-  Similar to `unfold/2` but the initial value is computed lazily via
-  `start_fun` and executes an `after_fun` at the end of enumeration
-  (both in cases of success and failure).
+  Similar to `transform/2` but the initial accumulated value is
+  computed lazily via `start_fun` and executes an `after_fun` at
+  the end of enumeration (both in cases of success and failure).

  Successive values are generated by calling `next_fun` with the
  previous accumulator (the initial value being the result returned
-  by `start_fun`) and it must return a tuple with the current and
-  next accumulator. The enumeration finishes if it returns `nil`.
+  by `start_fun`) and it must return a tuple containing a list
+  of items to be emitted and the next accumulator. The enumeration
+  finishes if it returns `{:halt, acc}`.

  As the name says, this function is useful to stream values from
  resources.
@@ -944,8 +1002,8 @@ defmodule Stream do
      Stream.resource(fn -> File.open!("sample") end,
                      fn file ->
                        case IO.read(file, :line) do
-                          data when is_binary(data) -> {data, file}
-                          _ -> nil
+                          data when is_binary(data) -> {[data], file}
+                          _ -> {:halt, file}
                        end
                      end,
                      fn file -> File.close(file) end)
@@ -967,9 +1025,11 @@ defmodule Stream do

  defp do_resource(next_acc, next_fun, {:cont, acc}, fun, after_fun) do
    try do
+      # Optimize the most common cases
      case next_fun.(next_acc) do
-        nil -> nil
-        {v, next_acc} -> {fun.(v, acc), next_acc}
+        {[], next_acc}  -> {:opt, {:cont, acc}, next_acc}
+        {[v], next_acc} -> {:opt, fun.(v, acc), next_acc}
+        {_, _} = other  -> other
      end
    catch
      kind, reason ->
@@ -977,11 +1037,62 @@ defmodule Stream do
        after_fun.(next_acc)
        :erlang.raise(kind, reason, stacktrace)
    else
-      nil ->
-        after_fun.(next_acc)
-        {:done, acc}
-      {acc, next_acc} ->
+      {:opt, acc, next_acc} ->
        do_resource(next_acc, next_fun, acc, fun, after_fun)
+      {:halt, next_acc} ->
+        do_resource(next_acc, next_fun, {:halt, acc}, fun, after_fun)
+      {list, next_acc} when is_list(list) ->
+        do_list_resource(next_acc, next_fun, {:cont, acc}, fun, after_fun,
+                         &Enumerable.List.reduce(list, &1, fun))
+      {enum, next_acc} ->
+        inner = &do_resource_each(&1, &2, fun)
+        do_enum_resource(next_acc, next_fun, {:cont, acc}, fun, after_fun,
+                         &Enumerable.reduce(enum, &1, inner))
+    end
+  end
+
+  defp do_list_resource(next_acc, next_fun, acc, fun, after_fun, reduce) do
+    try do
+      reduce.(acc)
+    catch
+      kind, reason ->
+        stacktrace = System.stacktrace
+        after_fun.(next_acc)
+        :erlang.raise(kind, reason, stacktrace)
+    else
+      {:done, acc} ->
+        do_resource(next_acc, next_fun, {:cont, acc}, fun, after_fun)
+      {:halted, acc} ->
+        do_resource(next_acc, next_fun, {:halt, acc}, fun, after_fun)
+      {:suspended, acc, c} ->
+        {:suspended, acc, &do_list_resource(next_acc, next_fun, &1, fun, after_fun, c)}
+    end
+  end
+
+  defp do_enum_resource(next_acc, next_fun, {op, acc}, fun, after_fun, reduce) do
+    try do
+      reduce.({op, [:outer|acc]})
+    catch
+      kind, reason ->
+        stacktrace = System.stacktrace
+        after_fun.(next_acc)
+        :erlang.raise(kind, reason, stacktrace)
+    else
+      {:halted, [:outer|acc]} ->
+        do_resource(next_acc, next_fun, {:cont, acc}, fun, after_fun)
+      {:halted, [:inner|acc]} ->
+        do_resource(next_acc, next_fun, {:halt, acc}, fun, after_fun)
+      {:done, [_|acc]} ->
+        do_resource(next_acc, next_fun, {:cont, acc}, fun, after_fun)
+      {:suspended, [_|acc], c} ->
+        {:suspended, acc, &do_enum_resource(next_acc, next_fun, &1, fun, after_fun, c)}
+    end
+  end
+
+  defp do_resource_each(x, [:outer|acc], f) do
+    case f.(x, acc) do
+      {:halt, res} -> {:halt, [:inner|res]}
+      {op, res}    -> {op, [:outer|res]}
    end
  end

@@ -1022,12 +1133,12 @@ defmodule Stream do

  @compile {:inline, lazy: 2, lazy: 3, lazy: 4}

-  defp lazy(%Stream{funs: funs} = lazy, fun),
+  defp lazy(%Stream{done: nil, funs: funs} = lazy, fun),
    do: %{lazy | funs: [fun|funs] }
  defp lazy(enum, fun),
    do: %Stream{enum: enum, funs: [fun]}

-  defp lazy(%Stream{funs: funs, accs: accs} = lazy, acc, fun),
+  defp lazy(%Stream{done: nil, funs: funs, accs: accs} = lazy, acc, fun),
    do: %{lazy | funs: [fun|funs], accs: [acc|accs] }
  defp lazy(enum, acc, fun),
    do: %Stream{enum: enum, funs: [fun], accs: [acc]}
@@ -1066,19 +1177,29 @@ defimpl Enumerable, for: Stream do
    case reduce.({command, [acc|accs]}) do
      {:suspended, [acc|accs], continuation} ->
        {:suspended, acc, &do_each(continuation, done, accs, &1)}
-      {:halted, [acc|_]} ->
-        {:halted, acc}
-      {:done, [acc|_] = accs} ->
-        case done do
-          nil ->
-            {:done, acc}
-          {done, fun} ->
-            case done.(fun).(accs) do
-              {:cont, [acc|_]}    -> {:done, acc}
+      {:halted, accs} ->
+        do_done {:halted, accs}, done
+      {:done, accs} ->
+        do_done {:done, accs}, done
+    end
+  end
+
+  defp do_done({reason, [acc|_]}, nil), do: {reason, acc}
+  defp do_done({reason, [acc|t]}, {done, fun}) do
+    [h|_] = Enum.reverse(t)
+    case done.([acc, h], fun) do
+      {:cont, [acc|_]}    -> {reason, acc}
      {:halt, [acc|_]}    -> {:halted, acc}
      {:suspend, [acc|_]} -> {:suspended, acc, &({:done, elem(&1, 1)})}
    end
  end
 end
+
+defimpl Inspect, for: Stream do
+  import Inspect.Algebra
+
+  def inspect(%{enum: enum, funs: funs}, opts) do
+    inner = [enum: enum, funs: Enum.reverse(funs)]
+    concat ["#Stream<", to_doc(inner, opts), ">"]
  end
 end
@@ -132,10 +132,16 @@ defmodule Stream.Reducers do
  defmacro take(f \\ nil) do
    quote do
      fn(entry, acc(h, n, t) = orig) ->
-        if n >= 1 do
-          cont_with_acc(unquote(f), entry, h, n-1, t)
-        else
+        case n do
+          0 ->
            {:halt, orig}
+          1 ->
+            case cont_with_acc(unquote(f), entry, h, n-1, t) do
+              {:cont, acc} -> {:halt, acc}
+              reason -> reason
+            end
+          _ ->
+            cont_with_acc(unquote(f), entry, h, n-1, t)
        end
      end
    end
@@ -4,28 +4,12 @@ defmodule String do
  @moduledoc ~S"""
  A String in Elixir is a UTF-8 encoded binary.

-  ## String and binary operations
-
-  The functions in this module act according to the
-  Unicode Standard, version 6.3.0. For example,
-  `capitalize/1`, `downcase/1`, `strip/1` are provided by this
-  module.
-
-  In addition to this module, Elixir provides more low-level
-  operations that work directly with binaries. Some
-  of those can be found in the `Kernel` module, as:
-
-    * `Kernel.binary_part/3` - retrieves part of the binary
-    * `Kernel.bit_size/1` and `Kernel.byte_size/1` - size related functions
-    * `Kernel.is_bitstring/1` and `Kernel.is_binary/1` - type checking function
-    * Plus a number of functions for working with binaries (bytes)
-      [in the `:binary` module](http://erlang.org/doc/man/binary.html)
-
  ## Codepoints and graphemes

-  As per the Unicode Standard, a codepoint is an Unicode
-  Character, which may be represented by one or more bytes.
-  For example, the character "é" is represented with two
+  The functions in this module act according to the Unicode
+  Standard, version 6.3.0.As per the standard, a codepoint is
+  an Unicode Character, which may be represented by one or more
+  bytes. For example, the character "é" is represented with two
  bytes:

      iex> byte_size("é")
@@ -66,34 +50,110 @@ defmodule String do
  This current Elixir version implements Extended Grapheme Cluster
  algorithm.

+  ## String and binary operations
+
+  To act accordingly to the Unicode Standard, many functions
+  in this module runs in linear time, as it needs to traverse
+  the whole string considering the proper Unicode codepoints.
+
+  For example, `String.length/1` is going to take longer as
+  the input grows. On the other hand, `byte_size/1` always runs
+  in constant time (i.e. regardless of the input size).
+
+  This means often there are performance costs in using the
+  functions in this module, compared to the more low-level
+  operations that work directly with binaries:
+
+    * `Kernel.binary_part/3` - retrieves part of the binary
+    * `Kernel.bit_size/1` and `Kernel.byte_size/1` - size related functions
+    * `Kernel.is_bitstring/1` and `Kernel.is_binary/1` - type checking function
+    * Plus a number of functions for working with binaries (bytes)
+      [in the `:binary` module](http://erlang.org/doc/man/binary.html)
+
+  There are many situations where using the `String` module can
+  be avoided in favor of binary functions or pattern matching.
+  For example, imagine you have a string `prefix` and you want to
+  remove this prefix from another string named `full`.
+
+  One may be tempted to write:
+
+      iex> take_prefix = fn full, prefix ->
+      ...>   base = String.length(prefix)
+      ...>   String.slice(full, base, String.length(full) - base)
+      ...> end
+      ...> take_prefix.("Mr. John", "Mr. ")
+      "John"
+
+  Although the function above works, it performs poorly. To
+  calculate the length of the string, we need to traverse it
+  fully, so we traverse both `prefix` and `full` strings, then
+  slice the `full` one, traversing it again.
+
+  A first attempting at improving it could be with ranges:
+
+      iex> take_prefix = fn full, prefix ->
+      ...>   base = String.length(prefix)
+      ...>   String.slice(full, base..-1)
+      ...> end
+      ...> take_prefix.("Mr. John", "Mr. ")
+      "John"
+
+  While this is much better (we don't traverse `full` twice),
+  it could still be improved. In this case, since we want to
+  extract a substring from a string, we can use `byte_size/1`
+  and `binary_part/3` as there is no chance we will slice in
+  the middle of a codepoint made of more than one byte:
+
+      iex> take_prefix = fn full, prefix ->
+      ...>   base = byte_size(prefix)
+      ...>   binary_part(full, base, byte_size(full) - base)
+      ...> end
+      ...> take_prefix.("Mr. John", "Mr. ")
+      "John"
+
+  Or simply used pattern matching:
+
+      iex> take_prefix = fn full, prefix ->
+      ...>   base = byte_size(prefix)
+      ...>   <<_ :: binary-size(base), rest :: binary>> = full
+      ...>   rest
+      ...> end
+      ...> take_prefix.("Mr. John", "Mr. ")
+      "John"
+
+  On the other hand, if you want to dynamically slice a string
+  based on an integer value, then using `String.slice/3` is the
+  best option as it guarantees we won't incorrectly split a valid
+  codepoint in multiple bytes.
+
  ## Integer codepoints

  Although codepoints could be represented as integers, this
  module represents all codepoints as strings. For example:

-      iex> String.codepoints("josé")
-      ["j", "o", "s", "é"]
+      iex> String.codepoints("olá")
+      ["o", "l", "á"]

  There are a couple of ways to retrieve a character integer
-  codepoint. One may use the `?` special macro:
+  codepoint. One may use the `?` construct:

-      iex> ?j
-      106
+      iex> ?o
+      111

-      iex> ?é
-      233
+      iex> ?á
+      225

  Or also via pattern matching:

-      iex> << eacute :: utf8 >> = "é"
+      iex> << eacute :: utf8 >> = "á"
      iex> eacute
-      233
+      225

  As we have seen above, codepoints can be inserted into
  a string by their hexadecimal code:

-      "jos\x{0065}\x{0301}" #=>
-      "josé"
+      "ol\x{0061}\x{0301}" #=>
+      "olá"

  ## Self-synchronization

@@ -129,7 +189,7 @@ defmodule String do
  @spec printable?(t) :: boolean

  def printable?(<< h :: utf8, t :: binary >>)
-      when h in ?\040..?\176
+      when h in 0x20..0x7E
      when h in 0xA0..0xD7FF
      when h in 0xE000..0xFFFD
      when h in 0x10000..0x10FFFF do
@@ -227,40 +287,53 @@ defmodule String do
  """
  @spec split(t, t | [t] | Regex.t) :: [t]
  @spec split(t, t | [t] | Regex.t, Keyword.t) :: [t]
-  def split(binary, pattern, options \\ [])
+  def split(string, pattern, options \\ [])

-  def split("", _pattern, _options), do: [""]
+  def split(string, "", options) do
+    parts = Keyword.get(options, :parts, :infinity)
+    split_codepoints(string, parts_to_index(parts), Keyword.get(options, :trim, false))
+  end

-  def split(binary, "", options), do: split(binary, ~r""u, options)
-
-  def split(binary, pattern, options) do
+  def split(string, pattern, options) do
    if Regex.regex?(pattern) do
-      Regex.split(pattern, binary, options)
+      Regex.split(pattern, string, options)
    else
-      splits =
-        case Keyword.get(options, :parts, :infinity) do
-          num when is_number(num) and num > 0 ->
-            split_parts(binary, pattern, num - 1)
-          _ ->
-            :binary.split(binary, pattern, [:global])
-        end
-
-      if Keyword.get(options, :trim, false) do
-        for split <- splits, split != "", do: split
+      parts = Keyword.get(options, :parts, :infinity)
+      trim  = Keyword.get(options, :trim, false)
+      if parts == :infinity and trim == false do
+        :binary.split(string, pattern, [:global])
      else
-        splits
+        split_parts(string, pattern, parts_to_index(parts), trim)
      end
    end
  end

-  defp split_parts("", _pattern, _num),         do: [""]
-  defp split_parts(binary, pattern, num),       do: split_parts(binary, pattern, num, [])
-  defp split_parts("", _pattern, _num, parts),  do: Enum.reverse([""|parts])
-  defp split_parts(binary, _pattern, 0, parts), do: Enum.reverse([binary|parts])
-  defp split_parts(binary, pattern, num, parts) do
-    case :binary.split(binary, pattern) do
-      [head]       -> Enum.reverse([head|parts])
-      [head, rest] -> split_parts(rest, pattern, num - 1, [head|parts])
+  defp parts_to_index(:infinity),                      do: 0
+  defp parts_to_index(n) when is_integer(n) and n > 0, do: n
+
+  defp split_codepoints(binary, 1, _trim), do: [binary]
+  defp split_codepoints(<<h :: utf8, t :: binary>>, count, trim),
+    do: [<<h :: utf8>>|split_codepoints(t, count - 1, trim)]
+  defp split_codepoints(<<h, t :: binary>>, count, trim),
+    do: [<<h>>|split_codepoints(t, count - 1, trim)]
+  defp split_codepoints(<<>>, _, true), do: []
+  defp split_codepoints(<<>>, _, false), do: [""]
+
+  defp split_parts("", _pattern, _num, true),   do: []
+  defp split_parts("", _pattern, _num, _trim),  do: [""]
+  defp split_parts(string, _pattern, 1, _trim), do: [string]
+  defp split_parts(string, pattern, num, trim) do
+    case :binary.split(string, pattern) do
+      [""] when trim ->
+        []
+      [head] ->
+        [head]
+      [head, tail] ->
+        if trim and head == "" do
+          split_parts(tail, pattern, num, trim)
+        else
+          [head|split_parts(tail, pattern, num-1, trim)]
+        end
    end
  end

@@ -322,8 +395,8 @@ defmodule String do
      iex> String.upcase("ab 123 xpto")
      "AB 123 XPTO"

-      iex> String.upcase("josé")
-      "JOSÉ"
+      iex> String.upcase("olá")
+      "OLÁ"

  """
  @spec upcase(t) :: t
@@ -340,8 +413,8 @@ defmodule String do
      iex> String.downcase("AB 123 XPTO")
      "ab 123 xpto"

-      iex> String.downcase("JOSÉ")
-      "josé"
+      iex> String.downcase("OLÁ")
+      "olá"

  """
  @spec downcase(t) :: t
@@ -364,8 +437,8 @@ defmodule String do
      iex> String.capitalize("ﬁn")
      "Fin"

-      iex> String.capitalize("josé")
-      "José"
+      iex> String.capitalize("olá")
+      "Olá"

  """
  @spec capitalize(t) :: t
@@ -405,7 +478,7 @@ defmodule String do
  # does not traverse the whole binary).
  def rstrip(string, char) when char in 0..127 do
    if :binary.last(string) == char do
-      do_rstrip(string, "", char)
+      rstrip(binary_part(string, 0, byte_size(string) - 1), char)
    else
      string
    end
@@ -577,13 +650,14 @@ defmodule String do
      iex> String.replace("a,b,c", ",", "-", global: false)
      "a-b,c"

-  The pattern can also be a regex. In those cases, one can give `\N`
-  in the `replacement` string to access a specific capture in the regex:
+  The pattern can also be a regex. In those cases, one can give `\N` or
+  `\g{N}` in the `replacement` string to access a specific capture in the
+  regex:

      iex> String.replace("a,b,c", ~r/,(.)/, ",\\1\\1")
      "a,bb,cc"

-  Notice we had to escape the escape character `\`. By giving `&`,
+  Notice we had to escape the escape character `\`. By giving `\0`,
  one can inject the whole matched pattern in the replacement string.

  When strings are used as a pattern, a developer can also use the
@@ -599,8 +673,8 @@ defmodule String do
      "a[,,]b[,,]c"

  """
-  @spec replace(t, t, t) :: t
-  @spec replace(t, t, t, Keyword.t) :: t
+  @spec replace(t, t | Regex.t, t) :: t
+  @spec replace(t, t | Regex.t, t, Keyword.t) :: t

  def replace(subject, pattern, replacement, options \\ []) when is_binary(replacement) do
    if Regex.regex?(pattern) do
@@ -672,8 +746,8 @@ defmodule String do

  ## Examples

-      iex> String.codepoints("josé")
-      ["j", "o", "s", "é"]
+      iex> String.codepoints("olá")
+      ["o", "l", "á"]

      iex> String.codepoints("оптими зации")
      ["о","п","т","и","м","и"," ","з","а","ц","и","и"]
@@ -699,8 +773,8 @@ defmodule String do

  ## Examples

-      iex> String.next_codepoint("josé")
-      {"j", "osé"}
+      iex> String.next_codepoint("olá")
+      {"o", "lá"}

  """
  @compile {:inline, next_codepoint: 1}
@@ -786,10 +860,10 @@ defmodule String do
  ## Examples

      iex> String.chunk(<<?a, ?b, ?c, 0>>, :valid)
-      ["abc\000"]
+      ["abc\0"]

      iex> String.chunk(<<?a, ?b, ?c, 0, 0x0ffff::utf8>>, :valid)
-      ["abc\000", <<0x0ffff::utf8>>]
+      ["abc\0", <<0x0ffff::utf8>>]

      iex> String.chunk(<<?a, ?b, ?c, 0, 0x0ffff::utf8>>, :printable)
      ["abc", <<0, 0x0ffff::utf8>>]
@@ -849,8 +923,8 @@ defmodule String do

  ## Examples

-      iex> String.next_grapheme("josé")
-      {"j", "osé"}
+      iex> String.next_grapheme("olá")
+      {"o", "lá"}

  """
  @compile {:inline, next_grapheme: 1}
@@ -974,8 +1048,13 @@ defmodule String do
  @doc """
  Returns a substring starting at the offset given by the first, and
  a length given by the second.
+
  If the offset is greater than string length, then it returns `""`.

+  Remember this function works with unicode codepoints and consider
+  the slices to represent codepoints offsets. If you want to split
+  on raw bytes, check `Kernel.binary_part/3` instead.
+
  ## Examples

      iex> String.slice("elixir", 1, 3)
@@ -1010,17 +1089,29 @@ defmodule String do
  end

  def slice(string, start, len) when start >= 0 and len >= 0 do
-    do_slice(next_grapheme(string), start, start + len - 1, 0, "")
+    case do_count_bytes(next_grapheme(string), start, 0) do
+      {nil, _} -> ""
+      {next, start_bytes} ->
+        {_, len_bytes} = do_count_bytes(next, len, 0)
+        binary_part(string, start_bytes, len_bytes)
+    end
  end

  def slice(string, start, len) when start < 0 and len >= 0 do
-    real_start_pos = length(string) - abs(start)
-    case real_start_pos >= 0 do
-      true -> do_slice(next_grapheme(string), real_start_pos, real_start_pos + len - 1, 0, "")
+    start = length(string) + start
+    case start >= 0 do
+      true  -> slice(string, start, len)
      false -> ""
    end
  end

+  defp do_count_bytes(next, 0, acc), do: {next, acc}
+  defp do_count_bytes(nil, _, acc),  do: {nil, acc}
+
+  defp do_count_bytes({char, rest}, counter, acc) do
+    do_count_bytes(next_grapheme(rest), counter - 1, acc + byte_size(char))
+  end
+
  @doc """
  Returns a substring from the offset given by the start of the
  range to the offset given by the end of the range.
@@ -1028,6 +1119,14 @@ defmodule String do
  If the start of the range is not a valid offset for the given
  string or if the range is in reverse order, returns `""`.

+  If the start or end of the range are negative, the whole string
+  is traversed first in order to convert the negative indexes into
+  positive ones.
+
+  Remember this function works with unicode codepoints and consider
+  the slices to represent codepoints offsets. If you want to split
+  on raw bytes, check `Kernel.binary_part/3` instead.
+
  ## Examples

      iex> String.slice("elixir", 1..3)
@@ -1060,54 +1159,51 @@ defmodule String do
      iex> String.slice("a", 1..1500)
      ""

-      iex> String.slice("a", 2..1500)
-      ""
-
  """
  @spec slice(t, Range.t) :: t

  def slice(string, range)

+  def slice("", _.._), do: ""
+
+  def slice(string, first..-1) when first >= 0 do
+    case do_count_bytes(next_grapheme(string), first, 0) do
+      {nil, _} -> ""
+      {_, start_bytes} -> binary_part(string, start_bytes, byte_size(string) - start_bytes)
+    end
+  end
+
  def slice(string, first..last) when first >= 0 and last >= 0 do
-    do_slice(next_grapheme(string), first, last, 0, "")
-  end
-
-  def slice(string, first..last) do
-    total = length(string)
-
-    if first < 0 do
-      first = total + first
-    end
-
-    if last < 0 do
-      last = total + last
-    end
-
-    if first >= 0 do
-      do_slice(next_grapheme(string), first, last, 0, "")
+    if last >= first do
+      slice(string, first, last - first + 1)
    else
      ""
    end
  end

-  defp do_slice(_, start_pos, last_pos, _, _) when start_pos > last_pos do
+  def slice(string, first..last) do
+    {bytes, length} = do_acc_bytes(next_grapheme(string), [], 0)
+
+    if first < 0, do: first = length + first
+    if last < 0,  do: last  = length + last
+
+    if first < 0 or first > last or first > length do
      ""
+    else
+      last  = min(last + 1, length)
+      bytes = Enum.drop(bytes, length - last)
+      first = last - first
+      {length_bytes, start_bytes} = Enum.split(bytes, first)
+      binary_part(string, Enum.sum(start_bytes), Enum.sum(length_bytes))
+    end
  end

-  defp do_slice({_, rest}, start_pos, last_pos, current_pos, acc) when current_pos < start_pos do
-    do_slice(next_grapheme(rest), start_pos, last_pos, current_pos + 1, acc)
+  defp do_acc_bytes({char, rest}, bytes, length) do
+    do_acc_bytes(next_grapheme(rest), [byte_size(char)|bytes], length + 1)
  end

-  defp do_slice({char, rest}, start_pos, last_pos, current_pos, acc) when current_pos >= start_pos and current_pos < last_pos do
-    do_slice(next_grapheme(rest), start_pos, last_pos, current_pos + 1, acc <> char)
-  end
-
-  defp do_slice({char, _}, start_pos, last_pos, current_pos, acc) when current_pos >= start_pos and current_pos == last_pos do
-    acc <> char
-  end
-  
-  defp do_slice(nil, _, _, _, acc) do
-    acc
+  defp do_acc_bytes(nil, bytes, length) do
+    {bytes, length}
  end

  @doc """
@@ -1328,7 +1424,7 @@ defmodule String do
      1023

  """
-  @spec to_integer(String.t, pos_integer) :: integer
+  @spec to_integer(String.t, 2..36) :: integer
  def to_integer(string, base) do
    :erlang.binary_to_integer(string, base)
  end
@@ -36,7 +36,7 @@ defmodule StringIO do
  """
  @spec open(binary, Keyword.t) :: {:ok, pid}
  def open(string, options \\ []) when is_binary(string) do
-    :gen_server.start_link(__MODULE__, {string, options}, [])
+    GenServer.start_link(__MODULE__, {string, options}, [])
  end

  @doc """
@@ -52,7 +52,7 @@ defmodule StringIO do
  """
  @spec contents(pid) :: {binary, binary}
  def contents(pid) when is_pid(pid) do
-    :gen_server.call(pid, :contents)
+    GenServer.call(pid, :contents)
  end

  @doc """
@@ -68,7 +68,7 @@ defmodule StringIO do
  """
  @spec close(pid) :: {:ok, {binary, binary}}
  def close(pid) when is_pid(pid) do
-    :gen_server.call(pid, :close)
+    GenServer.call(pid, :close)
  end

  ## callbacks
@@ -199,7 +199,7 @@ defmodule StringIO do
  end

  defp do_get_chars(input, :latin1, n) do
-    <<chars :: [binary, size(n)], rest :: binary>> = input
+    <<chars :: binary-size(n), rest :: binary>> = input
    {chars, rest}
  end

@@ -209,7 +209,7 @@ defmodule StringIO do
        {buf_count, split_pos} when buf_count < n or split_pos == :none ->
          {input, ""}
        {_buf_count, split_pos} ->
-          <<chars :: [binary, size(split_pos)], rest :: binary>> = input
+          <<chars :: binary-size(split_pos), rest :: binary>> = input
          {chars, rest}
      end
    catch
@@ -20,15 +20,15 @@ defmodule Supervisor do
      defmodule Stack do
        use GenServer

-        def start_link(state) do
-          GenServer.start_link(__MODULE__, state, [name: :sup_stack])
+        def start_link(state, opts) do
+          GenServer.start_link(__MODULE__, state, opts)
        end

        def handle_call(:pop, _from, [h|t]) do
          {:reply, h, t}
        end

-        def handle_cast({:push, h}, _from, t) do
+        def handle_cast({:push, h}, t) do
          {:noreply, [h|t]}
        end
      end
@@ -38,16 +38,17 @@ defmodule Supervisor do
      # Import helpers for defining supervisors
      import Supervisor.Spec

-      # We are going to supervise the Stack server which will
-      # be started with a single argument [:hello]
+      # We are going to supervise the Stack server which
+      # will be started with a single argument [:hello]
+      # and the default name of :sup_stack.
      children = [
-        worker(Stack, [[:hello]])
+        worker(Stack, [[:hello], [name: :sup_stack]])
      ]

      # Start the supervisor with our one child
      {:ok, pid} = Supervisor.start_link(children, strategy: :one_for_one)

-  Notice that when starting the GenServer, we have registered it
+  Notice that when starting the GenServer, we are registering it
  with name `:sup_stack`, which allows us to call it directly and
  get what is on the stack:

@@ -65,7 +66,7 @@ defmodule Supervisor do
  Let's try it:

      GenServer.call(:sup_stack, :pop)
-      =ERROR REPORT====
+      ** (exit) exited in: GenServer.call(:sup_stack, :pop, 5000)

  Luckily, since the server is being supervised by a supervisor, the
  supervisor will automatically start a new one, with the default stack
@@ -132,10 +133,74 @@ defmodule Supervisor do

    * `:simple_one_for_one` - similar to `:one_for_one` but suits better
      when dynamically attaching children. This strategy requires the
-      supervisor specification to contain only one children. Many functions
+      supervisor specification to contain only one child. Many functions
      in this module behave slightly differently when this strategy is
      used.

+  ## Simple one for one
+
+  The simple one for one supervisor is useful when you want to dynamically
+  start and stop supervisor children. For example, imagine you want to
+  dynamically create multiple stacks. We can do so by defining a simple one
+  for one supervisor:
+
+      # Import helpers for defining supervisors
+      import Supervisor.Spec
+
+      # This time, we don't pass any argument because
+      # the argument will be given when we start the child
+      children = [
+        worker(Stack, [], restart: :transient)
+      ]
+
+      # Start the supervisor with our one child
+      {:ok, sup_pid} = Supervisor.start_link(children, strategy: :simple_one_for_one)
+
+  There are a couple differences here:
+
+    * The simple one for one specification can define only one child which
+      works as a template for when we call `start_child/2`
+
+    * We have define the child to have restart strategy of transient. This
+      means that, if the child process exits due to a `:normal`, `:shutdown`
+      or `{:shutdown, term}` reason, it won't be restarted. This is useful
+      as it allows our workers to politely shutdown and be removed from the
+      simple one for one supervisor, without being restarted. You can find
+      more information about restart strategies on `Supervisor.Spec`
+
+  With the supervisor defined, let's dynamically start stacks:
+
+      {:ok, pid} = Supervisor.start_child(sup_pid, [[:hello, :world], []])
+      GenServer.call(pid, :pop) #=> :hello
+      GenServer.call(pid, :pop) #=> :world
+
+      {:ok, pid} = Supervisor.start_child(sup_pid, [[:something, :else], []])
+      GenServer.call(pid, :pop) #=> :something
+      GenServer.call(pid, :pop) #=> :else
+
+      Supervisor.count_children(sup_pid)
+      #=> %{active: 2, specs: 1, supervisors: 0, workers: 2}
+
+  ## Exit reasons
+
+  From the example above, you may have noticed that the transient restart
+  strategy for the worker does not restart the child in case it crashes with
+  reason `:normal`, `:shutdown` or `{:shutdown, term}`.
+
+  So one may ask: which exit reason should I choose when existing my worker?
+  There are three options:
+
+    * `:normal` - on such cases, the exit won't be logged, there is no restart
+      on transient mode and linked processes do not exit
+
+    * `:shutdown` or `{:shutdown, term}` - on such cases, the exit won't be
+      logged, there is no restart on transient mode and linked processes exit
+      with the same reason unless trapping exits
+
+    * any other term - on such cases, the exit will be logged, there are
+      restarts on transient mode and linked processes exit with the same reason
+      unless trapping exits
+
  ## Name Registration

  A supervisor is bound to the same name registration rules as a `GenServer`.
@@ -268,7 +333,9 @@ defmodule Supervisor do
  and child specification.
  """
  @spec start_child(supervisor, Supervisor.Spec.spec | [term]) :: on_start_child
-  defdelegate start_child(supervisor, child_spec_or_args), to: :supervisor
+  def start_child(supervisor, child_spec_or_args) do
+    call(supervisor, {:start_child, child_spec_or_args})
+  end

  @doc """
  Terminates the given pid or child id.
@@ -290,7 +357,9 @@ defmodule Supervisor do
  """
  @spec terminate_child(supervisor, pid | Supervisor.Spec.child_id) :: :ok | {:error, error}
        when error: :not_found | :simple_one_for_one
-  defdelegate terminate_child(supervisor, pid_or_child_id), to: :supervisor
+  def terminate_child(supervisor, pid_or_child_id) do
+    call(supervisor, {:terminate_child, pid_or_child_id})
+  end

  @doc """
  Deletes the child specification identified by `child_id`.
@@ -306,7 +375,9 @@ defmodule Supervisor do
  """
  @spec delete_child(supervisor, Supervisor.Spec.child_id) :: :ok | {:error, error}
        when error: :not_found | :simple_one_for_one | :running | :restarting
-  defdelegate delete_child(supervisor, child_id), to: :supervisor
+  def delete_child(supervisor, child_id) do
+    call(supervisor, {:delete_child, child_id})
+  end

  @doc """
  Restarts a child process identified by `child_id`.
@@ -335,7 +406,9 @@ defmodule Supervisor do
  @spec restart_child(supervisor, Supervisor.Spec.child_id) ::
        {:ok, child} | {:ok, child, term} | {:error, error}
        when error: :not_found | :simple_one_for_one | :running | :restarting | term
-  defdelegate restart_child(supervisor, child_id), to: :supervisor
+  def restart_child(supervisor, child_id) do
+    call(supervisor, {:restart_child, child_id})
+  end

  @doc """
  Returns a list with information about all children.
@@ -361,7 +434,9 @@ defmodule Supervisor do
           child | :restarting,
           Supervisor.Spec.worker,
           Supervisor.Spec.modules}]
-  defdelegate which_children(supervisor), to: :supervisor
+  def which_children(supervisor) do
+    call(supervisor, :which_children)
+  end

  @doc """
  Returns a map containing count values for the supervisor.
@@ -381,9 +456,15 @@ defmodule Supervisor do

  """
  @spec count_children(supervisor) ::
-        [specs: non_neg_integer, active: non_neg_integer,
-         supervisors: non_neg_integer, workers: non_neg_integer]
+        %{specs: non_neg_integer, active: non_neg_integer,
+          supervisors: non_neg_integer, workers: non_neg_integer}
  def count_children(supervisor) do
-    :supervisor.count_children(supervisor) |> :maps.from_list
+    call(supervisor, :count_children) |> :maps.from_list
+  end
+
+  @compile {:inline, call: 2}
+
+  defp call(supervisor, req) do
+    GenServer.call(supervisor, req, :infinity)
  end
 end
@@ -145,12 +145,12 @@ defmodule Supervisor.Spec do
      in the `Supervisor` module docs.

    * `:max_restarts` - the maximum amount of restarts allowed in
-      a time frame. Defaults to 5.
+      a time frame. Defaults to 3.

    * `:max_seconds` - the time frame in which `:max_restarts` applies.
      Defaults to 5.

-  The `:strategy` option is required and by default maximum 5 restarts
+  The `:strategy` option is required and by default maximum 3 restarts
  are allowed within 5 seconds. Please check the `Supervisor` module for
  a complete description of the available strategies.
  """
@@ -162,7 +162,7 @@ defmodule Supervisor.Spec do
      raise ArgumentError, "expected :strategy option to be given"
    end

-    maxR = Keyword.get(options, :max_restarts, 5)
+    maxR = Keyword.get(options, :max_restarts, 3)
    maxS = Keyword.get(options, :max_seconds, 5)

    assert_unique_ids(Enum.map(children, &elem(&1, 0)))
@@ -72,7 +72,7 @@ defmodule System do
  """
  @spec argv() :: [String.t]
  def argv do
-    :elixir_code_server.call :argv
+    :elixir_config.get(:argv)
  end

  @doc """
@@ -83,7 +83,7 @@ defmodule System do
  """
  @spec argv([String.t]) :: :ok
  def argv(args) do
-    :elixir_code_server.cast({:argv, args})
+    :elixir_config.put(:argv, args)
  end

  @doc """
@@ -94,11 +94,20 @@ defmodule System do
  """
  def cwd do
    case :file.get_cwd do
-      {:ok, base} -> IO.chardata_to_string(base)
+      {:ok, base} -> IO.chardata_to_string(fix_drive_letter(base))
      _ -> nil
    end
  end

+  defp fix_drive_letter([l, ?:, ?/ | rest] = original) when l in ?A..?Z do
+    case :os.type() do
+      {:win32, _} -> [l+?a-?A, ?:, ?/ | rest]
+      _ -> original
+    end
+  end
+
+  defp fix_drive_letter(original), do: original
+
  @doc """
  Current working directory, exception on error.

@@ -202,59 +211,32 @@ defmodule System do
  end

  @doc """
-  Register a program exit handler function.
+  Registers a program exit handler function.

-  Registers a function that will be invoked
-  at the end of program execution. Useful for
-  invoking a hook in "script" mode.
+  Registers a function that will be invoked at the end of program execution.
+  Useful for invoking a hook in "script" mode.

-  The function must receive the exit status code
-  as an argument.
+  The handler always executes in a different process from the one it was
+  registered in. As a consequence, any resources managed by the calling process
+  (ETS tables, open files, etc.) won't be available by the time the handler
+  function is invoked.
+
+  The function must receive the exit status code as an argument.
  """
  def at_exit(fun) when is_function(fun, 1) do
-    :elixir_code_server.cast {:at_exit, fun}
+    :elixir_config.update :at_exit, &[fun|&1]
  end

  @doc """
-  Execute a system command.
-
-  Executes `command` in a command shell of the target OS,
-  captures the standard output of the command and returns
-  the result as a binary.
-
-  If `command` is a char list, a char list is returned.
-  Otherwise a string, correctly encoded in UTF-8, is expected.
-  """
-  @spec cmd(String.t)  :: String.t
-  @spec cmd(char_list) :: char_list
-
-  def cmd(command) when is_list(command) do
-    :os.cmd(command)
-  end
-
-  def cmd(command) when is_binary(command) do
-    List.to_string :os.cmd(String.to_char_list(command))
-  end
-
-  @doc """
-  Locate an executable on the system.
+  Locates an executable on the system.

  This function looks up an executable program given
  its name using the environment variable PATH on Unix
  and Windows. It also considers the proper executable
  extension for each OS, so for Windows it will try to
  lookup files with `.com`, `.cmd` or similar extensions.
-
-  If `program` is a char list, a char list is returned.
-  Returns a binary otherwise.
  """
  @spec find_executable(binary) :: binary | nil
-  @spec find_executable(char_list) :: char_list | nil
-
-  def find_executable(program) when is_list(program) do
-    :os.find_executable(program) || nil
-  end
-
  def find_executable(program) when is_binary(program) do
    case :os.find_executable(String.to_char_list(program)) do
      false -> nil
@@ -387,4 +369,124 @@ defmodule System do
  def halt(status) when is_binary(status) do
    :erlang.halt(String.to_char_list(status))
  end
+
+  @doc """
+  Executes the given `command` with `args`.
+
+  `command` is expected to be an executable available in PATH
+  unless an absolute path is given.
+
+  `args` must be a list of strings which are not expanded
+  in any way. For example, this means wildcard expansion will
+  not happen unless `Path.wildcard/2` is used. On Windows though,
+  wildcard expansion is up to the program.
+
+  A set of options are also supported and described below.
+
+  ## Options
+
+    * `:into` - injects the result into the given collectable, defaults to `""`
+    * `:cd` - the directory to run the command in
+    * `:env` - an enumerable of tuples containing environment key-value as binary
+    * `:arg0` - set the command arg0
+    * `:stderr_to_stdout` - redirects stderr to stdout when true
+    * `:parallelism` - when true, the VM will schedule port tasks to improve
+      parallelism in the system. If set to false, the VM will try to perform
+      commands immediately, improving latency at the expense of parallelism.
+      The default can be set on system startup by passing the "+spp" argument
+      to `--erl`.
+
+  ## Error reasons
+
+  If invalid arguments are given, `ArgumentError` is raised by
+  `System.cmd/3`. `System.cmd/3` also expects a strict set of
+  options and will raise if unknown or invalid options are given.
+
+  Furthermore, `System.cmd/3` may fail with one of the POSIX reasons
+  detailed below:
+
+    * `:system_limit` - all available ports in the Erlang emulator are in use
+
+    * `:enomem` - there was not enough memory to create the port
+
+    * `:eagain` - there are no more available operating system processes
+
+    * `:enametoolong` - the external command given was too long
+
+    * `:emfile` - there are no more available file descriptors
+      (for the operating system process that the Erlang emulator runs in)
+
+    * `:enfile` - the file table is full (for the entire operating system)
+
+    * `:eacces` - the command does not point to an executable file
+
+    * `:enoent` - the command does not point to an existing file
+
+  ## Shell commands
+
+  If you desire to execute a trusted command inside a shell, with pipes,
+  redirecting and so on, please check
+  [Erlang's :os.cmd/1 function](http://www.erlang.org/doc/man/os.html#cmd-1).
+  """
+  @spec cmd(binary, [binary], Keyword.t) ::
+        {Collectable.t, exit_status :: non_neg_integer}
+  def cmd(command, args, opts \\ []) when is_binary(command) and is_list(args) do
+    cmd = String.to_char_list(command)
+
+    cmd =
+      if Path.type(cmd) == :absolute do
+        cmd
+      else
+        :os.find_executable(cmd) || :erlang.error(:enoent, [command, args, opts])
+      end
+
+    {into, opts} = cmd_opts(opts, [:use_stdio, :exit_status, :binary, :hide, args: args], "")
+    {initial, fun} = Collectable.into(into)
+    do_cmd Port.open({:spawn_executable, cmd}, opts), initial, fun
+  end
+
+  defp do_cmd(port, acc, fun) do
+    receive do
+      {^port, {:data, data}} ->
+        do_cmd(port, fun.(acc, {:cont, data}), fun)
+      {^port, {:exit_status, status}} ->
+        {fun.(acc, :done), status}
+    end
+  end
+
+  defp cmd_opts([{:into, any}|t], opts, _into),
+    do: cmd_opts(t, opts, any)
+
+  defp cmd_opts([{:cd, bin}|t], opts, into) when is_binary(bin),
+    do: cmd_opts(t, [{:cd, bin}|opts], into)
+
+  defp cmd_opts([{:arg0, bin}|t], opts, into) when is_binary(bin),
+    do: cmd_opts(t, [{:arg0, bin}|opts], into)
+
+  defp cmd_opts([{:stderr_to_stdout, true}|t], opts, into),
+    do: cmd_opts(t, [:stderr_to_stdout|opts], into)
+
+  defp cmd_opts([{:stderr_to_stdout, false}|t], opts, into),
+    do: cmd_opts(t, opts, into)
+
+  defp cmd_opts([{:parallelism, bool}|t], opts, into) when is_boolean(bool),
+    do: cmd_opts(t, [{:parallelism, bool}|opts], into)
+
+  defp cmd_opts([{:env, enum}|t], opts, into),
+    do: cmd_opts(t, [{:env, validate_env(enum)}|opts], into)
+
+  defp cmd_opts([{key, val}|_], _opts, _into),
+    do: raise(ArgumentError, "invalid option #{inspect key} with value #{inspect val}")
+
+  defp cmd_opts([], opts, into),
+    do: {into, opts}
+
+  defp validate_env(enum) do
+    Enum.map enum, fn
+      {k, v} ->
+        {String.to_char_list(k), String.to_char_list(v)}
+      other ->
+        raise ArgumentError, "invalid environment key-value #{inspect other}"
+    end
+  end
 end
@@ -58,7 +58,7 @@ defmodule Task do
  that dynamically supervise tasks:

      {:ok, pid} = Task.Supervisor.start_link()
-      Task.Supervisor.async(pid, fn -> do_work() end)
+      Task.Supervisor.async(pid, MyMod, :my_fun, [arg1, arg2, arg3])

  `Task.Supervisor` also makes it possible to spawn tasks in remote nodes as
  long as the supervisor is registered locally or globally:
@@ -67,7 +67,7 @@ defmodule Task do
      Task.Supervisor.start_link(name: :tasks_sup)

      # In the client
-      Task.Supervisor.async({:tasks_sup, :remote@local}, fn -> do_work() end)
+      Task.Supervisor.async({:tasks_sup, :remote@local}, MyMod, :my_fun, [arg1, arg2, arg3])

  `Task.Supervisor` is more often started in your supervision tree as:

@@ -77,7 +77,15 @@ defmodule Task do
        supervisor(Task.Supervisor, [[name: :tasks_sup]])
      ]

-  Check `Task.Supervisor` for other operations supported by the Task supervisor.
+  Note that, when working with distributed tasks, one should use the `async/3` API,
+  that expects explicit module, function and arguments, instead of `async/1` that
+  works with anonymous functions. That's because the anonymous function API expects
+  the same module version to exist on all involved nodes. Check the `Agent` module
+  documentation for more information on distributed processes, as the limitations
+  described in the agents documentation apply to the whole ecosystem.
+
+  Finally, check `Task.Supervisor` for other operations supported by the Task
+  supervisor.
  """

  @doc """
@@ -93,6 +101,8 @@ defmodule Task do
  """
  defstruct pid: nil, ref: nil

+  @type t :: %__MODULE__{}
+
  @doc """
  Starts a task as part of a supervision tree.
  """
@@ -109,6 +119,30 @@ defmodule Task do
    Task.Supervised.start_link(get_info(self), {mod, fun, args})
  end

+  @doc """
+  Starts a task.
+
+  This is only used when the task is used for side-effects
+  (i.e. no interest in its return result) and it should not
+  be linked to the current process.
+  """
+  @spec start(fun) :: {:ok, pid}
+  def start(fun) do
+    start(:erlang, :apply, [fun, []])
+  end
+
+  @doc """
+  Starts a task.
+
+  This is only used when the task is used for side-effects
+  (i.e. no interest in its return result) and it should not
+  be linked to the current process.
+  """
+  @spec start(module, atom, [term]) :: {:ok, pid}
+  def start(mod, fun, args) do
+    Task.Supervised.start(get_info(self), {mod, fun, args})
+  end
+
  @doc """
  Starts a task that can be awaited on.

@@ -150,7 +184,7 @@ defmodule Task do
  end

  @doc """
-  Awaits for a task reply.
+  Awaits a task reply.

  A timeout, in milliseconds, can be given with default value
  of `5000`. In case the task process dies, this function will
@@ -1,6 +1,10 @@
 defmodule Task.Supervised do
  @moduledoc false

+  def start(info, fun) do
+    {:ok, :proc_lib.spawn(__MODULE__, :noreply, [info, fun])}
+  end
+
  def start_link(info, fun) do
    {:ok, :proc_lib.spawn_link(__MODULE__, :noreply, [info, fun])}
  end
@@ -89,12 +93,12 @@ defmodule Task.Supervised do
    {fun, args} = get_running(mfa)

    :error_logger.format(
-      "** Task ~p terminating~n" <>
-      "** Started from ~p~n" <>
-      "** When function  == ~p~n" <>
-      "**      arguments == ~p~n" <>
-      "** Reason for termination == ~n" <>
-      "** ~p~n", [self, get_from(info), fun, args, reason])
+      '** Task ~p terminating~n' ++
+      '** Started from ~p~n' ++
+      '** When function  == ~p~n' ++
+      '**      arguments == ~p~n' ++
+      '** Reason for termination == ~n' ++
+      '** ~p~n', [self, get_from(info), fun, args, reason])

    exit(reason)
  end
@@ -25,14 +25,23 @@ defmodule Task.Supervisor do
    described under the `Name Registration` section in the `GenServer` module
    docs;

+  * `:restart` - the restart strategy, may be `:temporary` (the default),
+    `:transient` or `:permanent`. Check `Supervisor.Spec` for more info.
+    Defaults to temporary as most tasks can't be effectively restarted after
+    a crash;
+
  * `:shutdown` - `:brutal_kill` if the tasks must be killed directly on shutdown
    or an integer indicating the timeout value, defaults to 5000 milliseconds;
+
+  * `:max_restarts` and `:max_seconds` - as specified in `Supervisor.Spec.supervise/2`;
+
  """
  @spec start_link(Supervisor.options) :: Supervisor.on_start
  def start_link(opts \\ []) do
    import Supervisor.Spec
+    {restart, opts}  = Keyword.pop(opts, :restart, :temporary)
    {shutdown, opts} = Keyword.pop(opts, :shutdown, 5000)
-    children = [worker(Task.Supervised, [], restart: :temporary, shutdown: shutdown)]
+    children = [worker(Task.Supervised, [], restart: restart, shutdown: shutdown)]
    Supervisor.start_link(children, [strategy: :simple_one_for_one] ++ opts)
  end

@@ -7,20 +7,21 @@ defmodule URI do
            fragment: nil, authority: nil,
            userinfo: nil, host: nil, port: nil

+  @type t :: %__MODULE__{}
+
  import Bitwise

-  @ports %{
-    "ftp"   => 21,
-    "http"  => 80,
-    "https" => 443,
-    "ldap"  => 389,
-    "sftp"  => 22,
-    "tftp"  => 69,
-  }
+  @schemes [
+    "ftp",
+    "http",
+    "https",
+    "ldap",
+    "sftp",
+    "tftp",
+  ]

-  Enum.each @ports, fn {scheme, port} ->
+  Enum.each @schemes, fn scheme ->
    def normalize_scheme(unquote(scheme)), do: unquote(scheme)
-    def default_port(unquote(scheme)),     do: unquote(port)
  end

  @doc """
@@ -45,8 +46,7 @@ defmodule URI do

  """
  def default_port(scheme) when is_binary(scheme) do
-    {:ok, dict} = Application.fetch_env(:elixir, :uri)
-    Map.get(dict, scheme)
+    :elixir_config.get({:uri, scheme})
  end

  @doc """
@@ -57,8 +57,7 @@ defmodule URI do
  new URIs.
  """
  def default_port(scheme, port) when is_binary(scheme) and port > 0 do
-    {:ok, dict} = Application.fetch_env(:elixir, :uri)
-    Application.put_env(:elixir, :uri, Map.put(dict, scheme, port), persistent: true)
+    :elixir_config.put({:uri, scheme}, port)
  end

  @doc """
@@ -66,7 +65,7 @@ defmodule URI do

  Takes an enumerable (containing a sequence of two-item tuples)
  and returns a string of the form "key1=value1&key2=value2..." where
-  keys and values are URL encoded as per `encode/1`.
+  keys and values are URL encoded as per `encode/2`.

  Keys and values can be any term that implements the `String.Chars`
  protocol, except lists which are explicitly forbidden.
@@ -96,7 +95,10 @@ defmodule URI do

  """
  def decode_query(q, dict \\ %{}) when is_binary(q) do
-    Enum.reduce query_decoder(q), dict, fn({k, v}, acc) -> Dict.put(acc, k, v) end
+    case do_decode_query(q) do
+      nil         -> dict
+      {{k, v}, q} -> decode_query(q, Dict.put(dict, k, v))
+    end
  end

  @doc """
@@ -105,19 +107,19 @@ defmodule URI do

  ## Examples

-      iex> URI.query_decoder("foo=1&bar=2") |> Enum.map &(&1)
+      iex> URI.query_decoder("foo=1&bar=2") |> Enum.map(&(&1))
      [{"foo", "1"}, {"bar", "2"}]

  """
  def query_decoder(q) when is_binary(q) do
-    Stream.unfold(q, &do_decoder/1)
+    Stream.unfold(q, &do_decode_query/1)
  end

-  defp do_decoder("") do
+  defp do_decode_query("") do
    nil
  end

-  defp do_decoder(q) do
+  defp do_decode_query(q) do
    {first, next} =
      case :binary.split(q, "&") do
        [first, rest] -> {first, rest}
@@ -232,7 +234,7 @@ defmodule URI do

  """
  def decode(uri) do
-    unpercent(uri)
+    unpercent(uri, "", false)
  catch
    :malformed_uri ->
      raise ArgumentError, "malformed URI #{inspect uri}"
@@ -248,23 +250,25 @@ defmodule URI do

  """
  def decode_www_form(str) do
-    String.split(str, "+") |> Enum.map_join(" ", &unpercent/1)
+    unpercent(str, "", true)
  catch
    :malformed_uri ->
      raise ArgumentError, "malformed URI #{inspect str}"
  end

-  defp unpercent(<<?%, hex_1, hex_2, tail :: binary>>) do
-    <<bsl(hex_to_dec(hex_1), 4) + hex_to_dec(hex_2)>> <> unpercent(tail)
-  end
-  defp unpercent(<<?%, _>>), do: throw(:malformed_uri)
-  defp unpercent(<<?%>>),    do: throw(:malformed_uri)
-
-  defp unpercent(<<head, tail :: binary>>) do
-    <<head>> <> unpercent(tail)
+  defp unpercent(<<?+, tail::binary>>, acc, spaces = true) do
+    unpercent(tail, <<acc::binary, ?\s>>, spaces)
  end

-  defp unpercent(<<>>), do: <<>>
+  defp unpercent(<<?%, hex_1, hex_2, tail::binary>>, acc, spaces) do
+    unpercent(tail, <<acc::binary, bsl(hex_to_dec(hex_1), 4) + hex_to_dec(hex_2)>>, spaces)
+  end
+  defp unpercent(<<?%, _::binary>>, _acc, _spaces), do: throw(:malformed_uri)
+
+  defp unpercent(<<head, tail::binary>>, acc, spaces) do
+    unpercent(tail, <<acc::binary, head>>, spaces)
+  end
+  defp unpercent(<<>>, acc, _spaces), do: acc

  defp hex_to_dec(n) when n in ?A..?F, do: n - ?A + 10
  defp hex_to_dec(n) when n in ?a..?f, do: n - ?a + 10
@@ -272,12 +276,17 @@ defmodule URI do
  defp hex_to_dec(_n), do: throw(:malformed_uri)

  @doc """
-  Parses a URI into components.
+  Parses a well-formed URI reference into its components.

-  URIs have portions that are handled specially for the particular
-  scheme of the URI. For example, http and https have different
-  default ports. Such values can be accessed and registered via
-  `URI.default_port/1` and `URI.default_port/2`.
+  Note this function expects a well-formed URI and does not perform
+  any validation. See the examples section below of how `URI.parse/1`
+  can be used to parse a wide range of relative URIs.
+
+  This function uses the parsing regular expression as defined
+  in the Appendix B of RFC3986.
+
+  When a URI is given without a port, the values registered via
+  `URI.default_port/1` and `URI.default_port/2` are used.

  ## Examples

@@ -286,12 +295,24 @@ defmodule URI do
           authority: "elixir-lang.org", userinfo: nil,
           host: "elixir-lang.org", port: 80}

+      iex> URI.parse("//elixir-lang.org/")
+      %URI{authority: "elixir-lang.org", fragment: nil, host: "elixir-lang.org",
+           path: "/", port: nil, query: nil, scheme: nil, userinfo: nil}
+
+      iex> URI.parse("/foo/bar")
+      %URI{authority: nil, fragment: nil, host: nil, path: "/foo/bar",
+           port: nil, query: nil, scheme: nil, userinfo: nil}
+
+      iex> URI.parse("foo/bar")
+      %URI{authority: nil, fragment: nil, host: nil, path: "foo/bar",
+           port: nil, query: nil, scheme: nil, userinfo: nil}
+
  """
  def parse(%URI{} = uri), do: uri

  def parse(s) when is_binary(s) do
    # From http://tools.ietf.org/html/rfc3986#appendix-B
-    regex = ~r/^(([^:\/?#]+):)?(\/\/([^\/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?/
+    regex = ~r/^(([a-z][a-z0-9\+\-\.]*):)?(\/\/([^\/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?/i
    parts = nillify(Regex.run(regex, s))

    destructure [_, _, scheme, _, authority, path, _, query, _, fragment], parts
@@ -307,7 +328,7 @@ defmodule URI do

    scheme = normalize_scheme(scheme)

-    if nil?(port) and not nil?(scheme) do
+    if is_nil(port) and not is_nil(scheme) do
      port = default_port(scheme)
    end

@@ -347,12 +368,20 @@ defimpl String.Chars, for: URI do
      if uri.port == port, do: uri = %{uri | port: nil}
    end

+    # Based on http://tools.ietf.org/html/rfc3986#section-5.3
+
+    if uri.host do
+      authority = uri.host
+      if uri.userinfo, do: authority = uri.userinfo <> "@" <> authority
+      if uri.port, do: authority = authority <> ":" <> Integer.to_string(uri.port)
+    else
+      authority = uri.authority
+    end
+
    result = ""

-    if uri.scheme,   do: result = result <> uri.scheme <> "://"
-    if uri.userinfo, do: result = result <> uri.userinfo <> "@"
-    if uri.host,     do: result = result <> uri.host
-    if uri.port,     do: result = result <> ":" <> Integer.to_string(uri.port)
+    if uri.scheme,   do: result = result <> uri.scheme <> ":"
+    if authority,    do: result = result <> "//" <> authority
    if uri.path,     do: result = result <> uri.path
    if uri.query,    do: result = result <> "?" <> uri.query
    if uri.fragment, do: result = result <> "#" <> uri.fragment
@@ -51,6 +51,19 @@ defmodule Version do

      "~> 2.0.0"

+  `~>` will never include pre-release versions of its upper bound.
+  It can also be used to set an upper bound on only the major
+  version part. See the table below for `~>` requirements and
+  their corresponding translation.
+
+  `~>`           | Translation
+  :------------- | :---------------------
+  `~> 2.0.0`     | `>= 2.0.0 and < 2.1.0`
+  `~> 2.1.2`     | `>= 2.1.2 and < 2.2.0`
+  `~> 2.1.3-dev` | `>= 2.1.3-dev and < 2.2.0`
+  `~> 2.0`       | `>= 2.0.0 and < 3.0.0`
+  `~> 2.1`       | `>= 2.1.0 and < 3.0.0`
+
  """

  import Kernel, except: [match?: 2]
@@ -58,14 +71,26 @@ defmodule Version do

  @type version     :: String.t | t
  @type requirement :: String.t | Version.Requirement.t
-  @type matchable   :: {major :: String.t | non_neg_integer,
-                        minor :: non_neg_integer | nil,
-                        patch :: non_neg_integer | nil,
-                        pre   :: [String.t]}
+  @type major       :: String.t | non_neg_integer
+  @type minor       :: non_neg_integer | nil
+  @type patch       :: non_neg_integer | nil
+  @type pre         :: [String.t | non_neg_integer]
+  @type build       :: String.t | nil
+  @type matchable   :: {major :: major,
+                        minor :: minor,
+                        patch :: patch,
+                        pre   :: pre}
+  @type t           :: %__MODULE__{
+                         major: major,
+                         minor: minor,
+                         patch: patch,
+                         pre:   pre,
+                         build: build}

  defmodule Requirement do
    @moduledoc false
    defstruct [:source, :matchspec]
+    @type t :: %__MODULE__{}
  end

  defmodule InvalidRequirementError do
@@ -157,7 +182,8 @@ defmodule Version do

  ## Examples

-      iex> Version.parse("2.0.1-alpha1") |> elem(1)
+      iex> {:ok, version} = Version.parse("2.0.1-alpha1")
+      iex> version
      #Version<2.0.1-alpha1>

      iex> Version.parse("2.0-alpha1")
@@ -181,7 +207,8 @@ defmodule Version do

  ## Examples

-      iex> Version.parse_requirement("== 2.0.1") |> elem(1)
+      iex> {:ok, req} = Version.parse_requirement("== 2.0.1")
+      iex> req
      #Version.Requirement<== 2.0.1>

      iex> Version.parse_requirement("== == 2.0.1")
@@ -310,7 +337,7 @@ defmodule Version do
        patch = nillify(patch)
        pre   = nillify(pre)

-        if nil?(minor) or (nil?(patch) and not approximate?) do
+        if is_nil(minor) or (is_nil(patch) and not approximate?) do
          :error
        else
          major = String.to_integer(major)
@@ -492,10 +519,22 @@ end

 defimpl String.Chars, for: Version do
  def to_string(version) do
-    pre = unless Enum.empty?(pre = version.pre), do: "-#{pre}"
+    pre = pre(version.pre)
    build = if build = version.build, do: "+#{build}"
    "#{version.major}.#{version.minor}.#{version.patch}#{pre}#{build}"
  end
+
+  defp pre([]) do
+    ""
+  end
+
+  defp pre(pre) do
+    "-" <>
+      Enum.map_join(pre, ".", fn
+        int when is_integer(int) -> Integer.to_string(int)
+        string when is_binary(string) -> string
+      end)
+  end
 end

 defimpl Inspect, for: Version do
@@ -4,9 +4,6 @@ defmodule Elixir.Mixfile do
  def project do
    [app: :elixir,
     version: System.version,
-     build_per_environment: false,
-     escript_embed_elixir: false,
-     escript_main_module: :elixir,
-     escript_emu_args: "%%! -noshell\n"]
+     build_per_environment: false]
  end
 end
@@ -2,7 +2,7 @@
 %% private to the Elixir compiler and reserved to be used by Elixir only.
 -module(elixir).
 -behaviour(application).
-export([main/1, start_cli/0,
+-export([start_cli/0,
  string_to_quoted/4, 'string_to_quoted!'/4,
  env_for_eval/1, env_for_eval/2, quoted_to_erl/2, quoted_to_erl/3,
  eval/2, eval/3, eval_forms/3, eval_forms/4, eval_quoted/3]).
@@ -28,8 +28,13 @@ start(_Type, _Args) ->
      error   -> [binary]
    end,

-  io:setopts(standard_io, Opts),
-  io:setopts(standard_error, [{unicode,true}]),
+  ok = io:setopts(standard_io, Opts),
+
+  ok = case io:setopts(standard_error, [{encoding,utf8}]) of
+    ok         -> ok;
+    {error, _} -> io:setopts(standard_error, [{unicode,true}]) %% R17.3 and earlier
+  end,
+
  case file:native_name_encoding() of
    latin1 ->
      io:format(standard_error,
@@ -40,24 +45,48 @@ start(_Type, _Args) ->
      ok
  end,

-  elixir_sup:start_link().
+  URIs = [{<<"ftp">>, 21},
+          {<<"sftp">>, 22},
+          {<<"tftp">>, 69},
+          {<<"http">>, 80},
+          {<<"https">>, 443},
+          {<<"ldap">>, 389}],
+  URIConfig = [{{uri, Scheme}, Port} || {Scheme, Port} <- URIs],
+  CompilerOpts = [{docs,true},{debug_info,true},{warnings_as_errors,false}],
+  Config = [{at_exit, []},
+            {compiler_options, orddict:from_list(CompilerOpts)}
+            | URIConfig],
+  Tab = elixir_config:new(Config),
+  case elixir_sup:start_link() of
+    {ok, Sup} ->
+      {ok, Sup, Tab};
+    {error, _Reason} = Error ->
+      elixir_config:delete(Tab),
+      Error
+  end.
+
+stop(Tab) ->
+  elixir_config:delete(Tab).

-stop(_S) ->
-  ok.

 config_change(_Changed, _New, _Remove) ->
  ok.

-%% escript entry point
-
-main(Args) ->
-  application:start(?MODULE),
-  'Elixir.Kernel.CLI':main(Args).
-
 %% Boot and process given options. Invoked by Elixir's script.

 start_cli() ->
-  application:start(?MODULE),
+  {ok, _} = application:ensure_all_started(?MODULE),
+
+  %% We start the Logger so tools that depend on Elixir
+  %% always have the Logger directly accessible. However
+  %% Logger is not a dependency of the Elixir application,
+  %% which means releases that want to use Logger must
+  %% always list it as part of its applications.
+  _ = case code:ensure_loaded('Elixir.Logger') of
+    {module, _} -> application:start(logger);
+    {error, _}  -> ok
+  end,
+
  'Elixir.Kernel.CLI':main(init:get_plain_arguments()).

 %% EVAL HOOKS
@@ -153,14 +182,19 @@ eval_forms(Tree, Binding, Env, Scope) ->
    {atom, _, Atom} ->
      {Atom, Binding, NewEnv, NewScope};
    _  ->
-      {value, Value, NewBinding} = erl_eval(Erl, ParsedBinding),
+      {value, Value, NewBinding} = erl_eval(Erl, ParsedBinding, Env),
      {Value, elixir_scope:dump_binding(NewBinding, NewScope), NewEnv, NewScope}
  end.

-erl_eval(Erl, ParsedBinding) ->
+erl_eval(Erl, ParsedBinding, E) ->
+  case erl_eval:check_command([Erl], ParsedBinding) of
+    ok -> ok;
+    {error, Desc} -> elixir_errors:handle_file_error(?m(E, file), Desc)
+  end,
+
  % Below must be all one line for locations to be the same when the stacktrace
  % needs to be extended to the full stacktrace.
-  try erl_eval:expr(Erl, ParsedBinding) catch Class:Exception -> erlang:raise(Class, Exception, get_stacktrace()) end.
+  try erl_eval:expr(Erl, ParsedBinding, none, none, none) catch Class:Exception -> erlang:raise(Class, Exception, get_stacktrace()) end.

 get_stacktrace() ->
  Stacktrace = erlang:get_stacktrace(),
@@ -21,7 +21,7 @@

 -record(elixir_quote, {
  line=false,
-  keep=false,
+  file=nil,
  context=nil,
  vars_hygiene=true,
  aliases_hygiene=true,
@@ -41,28 +41,29 @@
 %% Used in tokenization and interpolation

 %% Numbers
-define(is_hex(S), ?is_digit(S) orelse (S >= $A andalso S =< $F) orelse (S >= $a andalso S =< $f)).
-define(is_bin(S), S >= $0 andalso S =< $1).
-define(is_octal(S), S >= $0 andalso S =< $7).
-define(is_leading_octal(S), S >= $0 andalso S =< $3).
+-define(is_hex(S), (?is_digit(S) orelse (S >= $A andalso S =< $F) orelse (S >= $a andalso S =< $f))).
+-define(is_bin(S), (S >= $0 andalso S =< $1)).
+-define(is_octal(S), (S >= $0 andalso S =< $7)).
+-define(is_leading_octal(S), (S >= $0 andalso S =< $3)).

 %% Digits and letters
-define(is_digit(S), S >= $0 andalso S =< $9).
-define(is_upcase(S), S >= $A andalso S =< $Z).
-define(is_downcase(S), S >= $a andalso S =< $z).
+-define(is_digit(S), (S >= $0 andalso S =< $9)).
+-define(is_upcase(S), (S >= $A andalso S =< $Z)).
+-define(is_downcase(S), (S >= $a andalso S =< $z)).

 %% Atoms
-define(is_atom_start(S), ?is_quote(S) orelse ?is_upcase(S) orelse ?is_downcase(S) orelse (S == $_)).
-define(is_atom(S), ?is_identifier(S) orelse (S == $@)).
+-define(is_atom_start(S), (?is_quote(S) orelse ?is_upcase(S) orelse ?is_downcase(S) orelse (S == $_))).
+-define(is_atom(S), (?is_identifier(S) orelse (S == $@))).

-define(is_identifier(S), ?is_digit(S) orelse ?is_upcase(S) orelse ?is_downcase(S) orelse (S == $_)).
-define(is_sigil(S), (S == $/) orelse (S == $<) orelse (S == $") orelse (S == $') orelse
-                     (S == $[) orelse (S == $() orelse (S == ${) orelse (S == $|)).
+-define(is_identifier(S), (?is_digit(S) orelse ?is_upcase(S) orelse ?is_downcase(S) orelse (S == $_))).
+-define(is_sigil(S), ((S == $/) orelse (S == $<) orelse (S == $") orelse (S == $') orelse
+                      (S == $[) orelse (S == $() orelse (S == ${) orelse (S == $|))).

 %% Quotes
-define(is_quote(S), S == $" orelse S == $').
+-define(is_quote(S), (S == $" orelse S == $')).

 %% Spaces
-define(is_horizontal_space(S), (S == $\s) orelse (S == $\t)).
-define(is_vertical_space(S), (S == $\r) orelse (S == $\n)).
-define(is_space(S), ?is_horizontal_space(S) orelse ?is_vertical_space(S)).
+-define(is_horizontal_space(S), ((S == $\s) orelse (S == $\t))).
+-define(is_vertical_space(S), ((S == $\r) orelse (S == $\n))).
+-define(is_space(S), (?is_horizontal_space(S) orelse ?is_vertical_space(S))).
+-define(is_invalid_space(S), (S == 16#A0)).
@@ -35,70 +35,99 @@ expand_bitstr(Fun, [H|T], Acc, E) ->

 %% Expand bit info

-expand_bit_info(Meta, Info, E) when is_list(Info) ->
-  expand_bit_info(Meta, Info, default, [], E);
-
 expand_bit_info(Meta, Info, E) ->
-  expand_bit_info(Meta, [Info], E).
+  expand_bit_info(Meta, unpack_bit_info(Info, []), default, [], E).

-expand_bit_info(Meta, [{Expr, ExprMeta, Args}|T], Size, Types, E) when is_atom(Expr) ->
-  ListArgs = if is_atom(Args) -> []; is_list(Args) -> Args end,
-  case expand_bit_type_or_size(Expr, ListArgs) of
-    type ->
-      {EArgs, EE} = elixir_exp:expand_args(ListArgs, E),
-      expand_bit_info(Meta, T, Size, [{Expr, [], EArgs}|Types], EE);
-    size ->
+expand_bit_info(Meta, [{size, _, [_]=Args}|T], Size, Types, E) ->
  case Size of
-        default -> ok;
-        _ -> elixir_errors:compile_error(Meta, ?m(E, file), "duplicated size definition in bitstring")
+    default ->
+      {[EArg], EE} = elixir_exp:expand_args(Args, E),
+
+      case EArg of
+        {Var, _, Context} when is_atom(Var) and is_atom(Context) ->
+          ok;
+        _ when is_integer(EArg) ->
+          ok;
+        _ ->
+          elixir_errors:compile_error(Meta, ?m(E, file),
+            "size in bitstring expects an integer or a variable as argument, got: ~ts",
+            ['Elixir.Macro':to_string(EArg)])
      end,
-      {EArgs, EE} = elixir_exp:expand_args(ListArgs, E),
-      expand_bit_info(Meta, T, {Expr, [], EArgs}, Types, EE);
-    none ->
-      handle_unknown_bit_info(Meta, {Expr, ExprMeta, ListArgs}, T, Size, Types, E)
+
+      expand_bit_info(Meta, T, {size, [], [EArg]}, Types, EE);
+    _ ->
+      elixir_errors:compile_error(Meta, ?m(E, file),
+        "duplicated size definition in bitstring")
  end;

-expand_bit_info(Meta, [Int|T], Size, Types, E) when is_integer(Int) ->
-  expand_bit_info(Meta, [{size, [], [Int]}|T], Size, Types, E);
+expand_bit_info(Meta, [{Expr, ExprMeta, Args}|T], Size, Types, E) when is_atom(Expr) ->
+  case expand_bit_type(Expr, Args) of
+    type ->
+      {EArgs, EE} = elixir_exp:expand_args(Args, E),
+      validate_bit_type_args(Meta, Expr, EArgs, EE),
+      expand_bit_info(Meta, T, Size, [{Expr, [], EArgs}|Types], EE);
+    none ->
+      handle_unknown_bit_info(Meta, {Expr, ExprMeta, Args}, T, Size, Types, E)
+  end;

 expand_bit_info(Meta, [Expr|_], _Size, _Types, E) ->
  elixir_errors:compile_error(Meta, ?m(E, file),
    "unknown bitstring specifier ~ts", ['Elixir.Kernel':inspect(Expr)]);

-expand_bit_info(_Meta, [], Size, Types, _) ->
-  case Size of
+expand_bit_info(Meta, [], Size, Types, _) ->
+  [H|T] = case Size of
    default -> lists:reverse(Types);
-    _ -> [Size|lists:reverse(Types)]
-  end.
+    _       -> lists:reverse(Types, [Size])
+  end,
+  lists:foldl(fun(I, Acc) -> {'-', Meta, [Acc, I]} end, H, T).

-expand_bit_type_or_size(binary, [])    -> type;
-expand_bit_type_or_size(integer, [])   -> type;
-expand_bit_type_or_size(float, [])     -> type;
-expand_bit_type_or_size(bitstring, []) -> type;
-expand_bit_type_or_size(bytes, [])     -> type;
-expand_bit_type_or_size(bits, [])      -> type;
-expand_bit_type_or_size(utf8, [])      -> type;
-expand_bit_type_or_size(utf16, [])     -> type;
-expand_bit_type_or_size(utf32, [])     -> type;
-expand_bit_type_or_size(signed, [])    -> type;
-expand_bit_type_or_size(unsigned, [])  -> type;
-expand_bit_type_or_size(big, [])       -> type;
-expand_bit_type_or_size(little, [])    -> type;
-expand_bit_type_or_size(native, [])    -> type;
-expand_bit_type_or_size(unit, [_])     -> type;
-expand_bit_type_or_size(size, [_])     -> size;
-expand_bit_type_or_size(_, _)          -> none.
+expand_bit_type(binary, [])    -> type;
+expand_bit_type(integer, [])   -> type;
+expand_bit_type(float, [])     -> type;
+expand_bit_type(bitstring, []) -> type;
+expand_bit_type(bytes, [])     -> type;
+expand_bit_type(bits, [])      -> type;
+expand_bit_type(utf8, [])      -> type;
+expand_bit_type(utf16, [])     -> type;
+expand_bit_type(utf32, [])     -> type;
+expand_bit_type(signed, [])    -> type;
+expand_bit_type(unsigned, [])  -> type;
+expand_bit_type(big, [])       -> type;
+expand_bit_type(little, [])    -> type;
+expand_bit_type(native, [])    -> type;
+expand_bit_type(unit, [_])     -> type;
+expand_bit_type(_, _)          -> none.

-handle_unknown_bit_info(Meta, {_, ExprMeta, _} = Expr, T, Size, Types, E) ->
-  case 'Elixir.Macro':expand(Expr, elixir_env:linify({?line(ExprMeta), E})) of
+validate_bit_type_args(Meta, unit, [Unit], E) when not is_integer(Unit) ->
+  elixir_errors:compile_error(Meta, ?m(E, file),
+    "unit in bitstring expects an integer as argument, got: ~ts",
+    ['Elixir.Macro':to_string(Unit)]);
+validate_bit_type_args(_Meta, _Expr, _Args, _E) ->
+  ok.
+
+handle_unknown_bit_info(Meta, Expr, T, Size, Types, E) ->
+  case 'Elixir.Macro':expand(Expr, elixir_env:linify({?line(Meta), E})) of
    Expr ->
-      elixir_errors:compile_error(ExprMeta, ?m(E, file),
+      elixir_errors:compile_error(Meta, ?m(E, file),
        "unknown bitstring specifier ~ts", ['Elixir.Macro':to_string(Expr)]);
-    Other ->
-      List = case is_list(Other) of true -> Other; false -> [Other] end,
-      expand_bit_info(Meta, List ++ T, Size, Types, E)
+    Info ->
+      expand_bit_info(Meta, unpack_bit_info(Info, []) ++ T, Size, Types, E)
  end.

+unpack_bit_info({'-', _, [H, T]}, Acc) ->
+  unpack_bit_info(H, unpack_bit_info(T, Acc));
+unpack_bit_info({'*', _, [{'_', _, Atom}, Unit]}, Acc) when is_atom(Atom) and is_integer(Unit) ->
+  [{unit, [], [Unit]}|Acc];
+unpack_bit_info({'*', _, [Size, Unit]}, Acc) when is_integer(Size) and is_integer(Unit) ->
+  [{size, [], [Size]}, {unit, [], [Unit]}|Acc];
+unpack_bit_info(Size, Acc) when is_integer(Size) ->
+  [{size, [], [Size]}|Acc];
+unpack_bit_info({Expr, Meta, Args}, Acc) when is_atom(Expr) ->
+  ListArgs = if is_atom(Args) -> []; is_list(Args) -> Args end,
+  [{Expr, Meta, ListArgs}|Acc];
+unpack_bit_info(Other, Acc) ->
+  [Other|Acc].
+
 %% Translation

 has_size({bin, _, Elements}) ->
@@ -124,7 +153,7 @@ build_bitstr_each(_Fun, [], _Meta, S, Acc) ->
  {Acc, S};

 build_bitstr_each(Fun, [{'::',_,[H,V]}|T], Meta, S, Acc) ->
-  {Size, Types} = extract_bit_info(Meta, V, S#elixir_scope{context=nil}),
+  {Size, Types} = extract_bit_info(V, S#elixir_scope{context=nil}),
  build_bitstr_each(Fun, T, Meta, S, Acc, H, Size, Types);

 build_bitstr_each(Fun, [H|T], Meta, S, Acc) ->
@@ -201,23 +230,20 @@ unit_size([], Guess)           -> Guess.

 %% Extra bitstring specifiers

-extract_bit_info(Meta, [{size, _, [Arg]}|T], S) ->
-  case elixir_translator:translate(Arg, S) of
-    {{Kind, _, _} = Size, _} when Kind == integer; Kind == var ->
-      {Size, extract_bit_type(Meta, T, S)};
-    _ ->
-      elixir_errors:compile_error(Meta, S#elixir_scope.file,
-        "size in bitstring expects an integer or a variable as argument, got: ~ts", ['Elixir.Macro':to_string(Arg)])
-  end;
-extract_bit_info(Meta, T, S) ->
-  {default, extract_bit_type(Meta, T, S)}.
+extract_bit_info({'-', _, [L, {size, _, [Size]}]}, S) ->
+  {extract_bit_size(Size, S), extract_bit_type(L, [])};
+extract_bit_info({size, _, [Size]}, S) ->
+  {extract_bit_size(Size, S), []};
+extract_bit_info(L, _S) ->
+  {default, extract_bit_type(L, [])}.

-extract_bit_type(Meta, [{unit, _, [Arg]}|T], S) when is_integer(Arg) ->
-  [{unit, Arg}|extract_bit_type(Meta, T, S)];
-extract_bit_type(Meta, [{unit, _, [Arg]}|_], S) ->
-  elixir_errors:compile_error(Meta, S#elixir_scope.file,
-    "unit in bitstring expects an integer as argument, got: ~ts", ['Elixir.Macro':to_string(Arg)]);
-extract_bit_type(Meta, [{Other, _, []}|T], S) ->
-  [Other|extract_bit_type(Meta, T, S)];
-extract_bit_type(_Meta, [], _S) ->
-  [].
+extract_bit_size(Size, S) ->
+  {TSize, _} = elixir_translator:translate(Size, S),
+  TSize.
+
+extract_bit_type({'-', _, [L, R]}, Acc) ->
+  extract_bit_type(L, extract_bit_type(R, Acc));
+extract_bit_type({unit, _, [Arg]}, Acc) ->
+  [{unit, Arg}|Acc];
+extract_bit_type({Other, _, []}, Acc) ->
+  [Other|Acc].
@@ -6,13 +6,11 @@

 -define(timeout, 30000).
 -record(elixir_code_server, {
-  compilation_status=[],
-  argv=[],
  loaded=[],
-  at_exit=[],
-  pool={[],0},
-  compiler_options=[{docs,true},{debug_info,true},{warnings_as_errors,false}],
-  erl_compiler_options=nil
+  paths={[],[]},
+  mod_pool={[],0},
+  mod_ets=dict:new(),
+  compilation_status=[]
 }).

 call(Args) ->
@@ -27,11 +25,22 @@ start_link() ->
  gen_server:start_link({local, ?MODULE}, ?MODULE, ok, []).

 init(ok) ->
-  code:ensure_loaded('Elixir.Macro.Env'),
-  code:ensure_loaded('Elixir.Module.LocalsTracker'),
-  code:ensure_loaded('Elixir.Kernel.LexicalTracker'),
+  %% We attempt to load those modules here so throughout
+  %% the codebase we can avoid code:is_loaded/1 checks.
+  _ = code:ensure_loaded('Elixir.Macro.Env'),
+
+  %% The table where we store module definitions
+  _ = ets:new(elixir_modules, [set, protected, named_table, {read_concurrency, true}]),
+
  {ok, #elixir_code_server{}}.

+handle_call({defmodule, Pid, Tuple}, _From, Config) ->
+  {Ref, New} = defmodule(Pid, Tuple, Config),
+  {reply, Ref, New};
+
+handle_call({undefmodule, Ref}, _From, Config) ->
+  {reply, ok, undefmodule(Ref, Config)};
+
 handle_call({acquire, Path}, From, Config) ->
  Current = Config#elixir_code_server.loaded,
  case orddict:find(Path, Current) of
@@ -48,58 +57,32 @@ handle_call({acquire, Path}, From, Config) ->
 handle_call(loaded, _From, Config) ->
  {reply, [F || {F, true} <- Config#elixir_code_server.loaded], Config};

-handle_call(at_exit, _From, Config) ->
-  {reply, Config#elixir_code_server.at_exit, Config};
-
-handle_call(flush_at_exit, _From, Config) ->
-  {reply, Config#elixir_code_server.at_exit, Config#elixir_code_server{at_exit=[]}};
-
-handle_call(argv, _From, Config) ->
-  {reply, Config#elixir_code_server.argv, Config};
-
-handle_call(compiler_options, _From, Config) ->
-  {reply, Config#elixir_code_server.compiler_options, Config};
-
 handle_call({compilation_status, CompilerPid}, _From, Config) ->
  CompilationStatusList    = Config#elixir_code_server.compilation_status,
  CompilationStatusListNew = orddict:erase(CompilerPid, CompilationStatusList),
  CompilationStatus        = orddict:fetch(CompilerPid, CompilationStatusList),
-  {reply, CompilationStatus, Config#elixir_code_server{compilation_status=CompilationStatusListNew}};
+  {reply, CompilationStatus,
+   Config#elixir_code_server{compilation_status=CompilationStatusListNew}};

 handle_call(retrieve_module_name, _From, Config) ->
-  case Config#elixir_code_server.pool of
+  case Config#elixir_code_server.mod_pool of
    {[H|T], Counter} ->
-      {reply, module_tuple(H), Config#elixir_code_server{pool={T,Counter}}};
+      {reply, module_tuple(H), Config#elixir_code_server{mod_pool={T,Counter}}};
    {[], Counter} ->
-      {reply, module_tuple(Counter), Config#elixir_code_server{pool={[],Counter+1}}}
+      {reply, module_tuple(Counter), Config#elixir_code_server{mod_pool={[],Counter+1}}}
  end;

-handle_call(erl_compiler_options, _From, Config) ->
-  case Config#elixir_code_server.erl_compiler_options of
-    nil ->
-      Opts = erl_compiler_options(),
-      {reply, Opts, Config#elixir_code_server{erl_compiler_options=Opts}};
-    Opts ->
-      {reply, Opts, Config}
-  end;
+handle_call(paths, _From, Config) ->
+  {reply, Config#elixir_code_server.paths, Config};

 handle_call(Request, _From, Config) ->
  {stop, {badcall, Request}, Config}.

-handle_cast({at_exit, AtExit}, Config) ->
-  {noreply, Config#elixir_code_server{at_exit=[AtExit|Config#elixir_code_server.at_exit]}};
-
-handle_cast({argv, Argv}, Config) ->
-  {noreply, Config#elixir_code_server{argv=Argv}};
-
-handle_cast({compiler_options, Options}, Config) ->
-  Final = orddict:merge(fun(_,_,V) -> V end, Config#elixir_code_server.compiler_options, Options),
-  {noreply, Config#elixir_code_server{compiler_options=Final}};
-
 handle_cast({register_warning, CompilerPid}, Config) ->
  CompilationStatusCurrent = Config#elixir_code_server.compilation_status,
  CompilationStatusNew     = orddict:store(CompilerPid, error, CompilationStatusCurrent),
-  case orddict:find(warnings_as_errors, Config#elixir_code_server.compiler_options) of
+  CompilerOptions          = elixir_config:get(compiler_options),
+  case orddict:find(warnings_as_errors, CompilerOptions) of
    {ok, true} -> {noreply, Config#elixir_code_server{compilation_status=CompilationStatusNew}};
    _ -> {noreply, Config}
  end;
@@ -115,7 +98,7 @@ handle_cast({loaded, Path}, Config) ->
    {ok, true} ->
      {noreply, Config};
    {ok, {Ref, List}} when is_list(List), is_reference(Ref) ->
-      [Pid ! {elixir_code_server, Ref, loaded} || {Pid, _Tag} <- lists:reverse(List)],
+      _ = [Pid ! {elixir_code_server, Ref, loaded} || {Pid, _Tag} <- lists:reverse(List)],
      Done = orddict:store(Path, true, Current),
      {noreply, Config#elixir_code_server{loaded=Done}};
    error ->
@@ -128,13 +111,19 @@ handle_cast({unload_files, Files}, Config) ->
  Unloaded = lists:foldl(fun(File, Acc) -> orddict:erase(File, Acc) end, Current, Files),
  {noreply, Config#elixir_code_server{loaded=Unloaded}};

-handle_cast({return_module_name, H}, #elixir_code_server{pool={T,Counter}} = Config) ->
-  {noreply, Config#elixir_code_server{pool={[H|T],Counter}}};
+handle_cast({return_module_name, H}, #elixir_code_server{mod_pool={T,Counter}} = Config) ->
+  {noreply, Config#elixir_code_server{mod_pool={[H|T],Counter}}};
+
+handle_cast({paths, PA, PZ}, #elixir_code_server{} = Config) ->
+  {noreply, Config#elixir_code_server{paths={PA,PZ}}};

 handle_cast(Request, Config) ->
  {stop, {badcast, Request}, Config}.

-handle_info(_Request, Config) ->
+handle_info({'DOWN', Ref, process, _Pid, _Reason}, Config) ->
+  {noreply, undefmodule(Ref, Config)};
+
+handle_info(_Msg, Config) ->
  {noreply, Config}.

 terminate(_Reason, _Config) ->
@@ -146,22 +135,17 @@ code_change(_Old, Config, _Extra) ->
 module_tuple(I) ->
  {list_to_atom("elixir_compiler_" ++ integer_to_list(I)), I}.

-erl_compiler_options() ->
-  Key = "ERL_COMPILER_OPTIONS",
-  case os:getenv(Key) of
-    false -> [];
-    Str when is_list(Str) ->
-      case erl_scan:string(Str) of
-        {ok,Tokens,_} ->
-          case erl_parse:parse_term(Tokens ++ [{dot, 1}]) of
-            {ok,List} when is_list(List) -> List;
-            {ok,Term} -> [Term];
-            {error,_Reason} ->
-              io:format("Ignoring bad term in ~ts\n", [Key]),
-              []
-          end;
-        {error, {_,_,_Reason}, _} ->
-          io:format("Ignoring bad term in ~ts\n", [Key]),
-          []
-      end
+defmodule(Pid, Tuple, #elixir_code_server{mod_ets=ModEts} = Config) ->
+  ets:insert(elixir_modules, Tuple),
+  Ref = erlang:monitor(process, Pid),
+  Mod = erlang:element(1, Tuple),
+  {Ref, Config#elixir_code_server{mod_ets=dict:store(Ref, Mod, ModEts)}}.
+
+undefmodule(Ref, #elixir_code_server{mod_ets=ModEts} = Config) ->
+  case dict:find(Ref, ModEts) of
+    {ok, Mod} ->
+      ets:delete(elixir_modules, Mod),
+      Config#elixir_code_server{mod_ets=dict:erase(Ref, ModEts)};
+    error ->
+      Config
  end.
@@ -1,12 +1,12 @@
 -module(elixir_compiler).
-export([get_opt/1, string/2, quoted/2, file/1, file_to_path/2]).
+-export([get_opt/1, string/2, quoted/2, file/1, file/2, file_to_path/2]).
 -export([core/0, module/4, eval_forms/3]).
 -include("elixir.hrl").

 %% Public API

 get_opt(Key) ->
-  Dict = elixir_code_server:call(compiler_options),
+  Dict = elixir_config:get(compiler_options),
  case lists:keyfind(Key, 1, Dict) of
    false -> false;
    {Key, Value} -> Value
@@ -15,15 +15,19 @@ get_opt(Key) ->
 %% Compilation entry points.

 string(Contents, File) when is_list(Contents), is_binary(File) ->
+  string(Contents, File, nil).
+string(Contents, File, Dest) ->
  Forms = elixir:'string_to_quoted!'(Contents, 1, File, []),
-  quoted(Forms, File).
+  quoted(Forms, File, Dest).

 quoted(Forms, File) when is_binary(File) ->
+  quoted(Forms, File, nil).
+quoted(Forms, File, Dest) ->
  Previous = get(elixir_compiled),

  try
    put(elixir_compiled, []),
-    elixir_lexical:run(File, fun
+    elixir_lexical:run(File, Dest, fun
      (Pid) ->
        Env = elixir:env_for_eval([{line,1},{file,File}]),
        eval_forms(Forms, [], Env#{lexical_tracker := Pid})
@@ -34,14 +38,20 @@ quoted(Forms, File) when is_binary(File) ->
  end.

 file(Relative) when is_binary(Relative) ->
+  file(Relative, nil).
+file(Relative, Dest) ->
  File = filename:absname(Relative),
  {ok, Bin} = file:read_file(File),
-  string(elixir_utils:characters_to_list(Bin), File).
+  string(elixir_utils:characters_to_list(Bin), File, case Dest of
+    nil -> Dest;
+    _   -> filename:absname(Dest)
+  end).

-file_to_path(File, Path) when is_binary(File), is_binary(Path) ->
-  Lists = file(File),
-  [binary_to_path(X, Path) || X <- Lists],
-  Lists.
+file_to_path(File, Dest) when is_binary(File), is_binary(Dest) ->
+  Comp = file(File, Dest),
+  Abs  = filename:absname(Dest),
+  _ = [binary_to_path(X, Abs) || X <- Comp],
+  Comp.

 %% Evaluation

@@ -68,9 +78,9 @@ code_loading_compilation(Forms, Vars, #{line := Line} = E) ->

  %% Pass {native, false} to speed up bootstrap
  %% process when native is set to true
-  AllOpts   = elixir_code_server:call(erl_compiler_options),
+  AllOpts   = options(),
  FinalOpts = AllOpts -- [native, warn_missing_spec],
-  module(Form, ?m(E, file), FinalOpts, true, fun(_, Binary) ->
+  inner_module(Form, FinalOpts, true, E, fun(_, Binary) ->
    %% If we have labeled locals, anonymous functions
    %% were created and therefore we cannot ditch the
    %% module
@@ -82,6 +92,36 @@ code_loading_compilation(Forms, Vars, #{line := Line} = E) ->
    dispatch_loaded(Module, Fun, Args, Purgeable, I, EE)
  end).

+options() ->
+  case elixir_config:get(erl_compiler_options) of
+    nil ->
+      elixir_config:update(erl_compiler_options, fun options/1);
+    Opts ->
+      Opts
+  end.
+
+options(nil) ->
+  Key = "ERL_COMPILER_OPTIONS",
+  case os:getenv(Key) of
+    false -> [];
+    Str when is_list(Str) ->
+      case erl_scan:string(Str) of
+        {ok,Tokens,_} ->
+          case erl_parse:parse_term(Tokens ++ [{dot, 1}]) of
+            {ok,List} when is_list(List) -> List;
+            {ok,Term} -> [Term];
+            {error,_Reason} ->
+              io:format("Ignoring bad term in ~ts\n", [Key]),
+              []
+          end;
+        {error, {_,_,_Reason}, _} ->
+          io:format("Ignoring bad term in ~ts\n", [Key]),
+          []
+      end
+  end;
+options(Opts) ->
+    Opts.
+
 dispatch_loaded(Module, Fun, Args, Purgeable, I, E) ->
  Res = Module:Fun(Args),
  code:delete(Module),
@@ -128,43 +168,55 @@ allows_fast_compilation(_) -> false.
 %% Compile the module by forms based on the scope information
 %% executes the callback in case of success. This automatically
 %% handles errors and warnings. Used by this module and elixir_module.
-module(Forms, File, Opts, Callback) ->
+module(Forms, Opts, E, Callback) ->
  Final =
    case (get_opt(debug_info) == true) orelse
         lists:member(debug_info, Opts) of
-      true  -> [debug_info] ++ elixir_code_server:call(erl_compiler_options);
-      false -> elixir_code_server:call(erl_compiler_options)
+      true  -> [debug_info] ++ options();
+      false -> options()
    end,
-  module(Forms, File, Final, false, Callback).
+  inner_module(Forms, Final, false, E, Callback).

-module(Forms, File, Options, Bootstrap, Callback) when
-    is_binary(File), is_list(Forms), is_list(Options), is_boolean(Bootstrap), is_function(Callback) ->
-  Listname = elixir_utils:characters_to_list(File),
+inner_module(Forms, Options, Bootstrap, #{file := File} = E, Callback) when
+    is_list(Forms), is_list(Options), is_boolean(Bootstrap), is_function(Callback) ->
+  Source = elixir_utils:characters_to_list(File),

-  case compile:noenv_forms([no_auto_import()|Forms], [return,{source,Listname}|Options]) of
-    {ok, ModuleName, Binary, Warnings} ->
+  case compile:noenv_forms([no_auto_import()|Forms], [return,{source,Source}|Options]) of
+    {ok, Module, Binary, Warnings} ->
      format_warnings(Bootstrap, Warnings),
-      code:load_binary(ModuleName, Listname, Binary),
-      Callback(ModuleName, Binary);
+      {module, Module} = code:load_binary(Module, beam_location(E), Binary),
+      Callback(Module, Binary);
    {error, Errors, Warnings} ->
      format_warnings(Bootstrap, Warnings),
      format_errors(Errors)
  end.

+beam_location(#{module := nil}) -> in_memory;
+beam_location(#{lexical_tracker := Pid, module := Module}) ->
+  case elixir_lexical:dest(Pid) of
+    nil  -> in_memory;
+    Dest ->
+      filename:join(elixir_utils:characters_to_list(Dest),
+                    atom_to_list(Module) ++ ".beam")
+  end.
+
 no_auto_import() ->
  {attribute, 0, compile, no_auto_import}.

 %% CORE HANDLING

 core() ->
-  application:start(elixir),
-  elixir_code_server:cast({compiler_options, [{docs,false},{internal,true}]}),
+  {ok, _} = application:ensure_all_started(elixir),
+  New = orddict:from_list([{docs,false},{internal,true}]),
+  Merge = fun(_, _, Value) -> Value end,
+  Update = fun(Old) -> orddict:merge(Merge, Old, New) end,
+  _ = elixir_config:update(compiler_options, Update),
  [core_file(File) || File <- core_main()].

 core_file(File) ->
  try
    Lists = file(File),
-    [binary_to_path(X, "lib/elixir/ebin") || X <- Lists],
+    _ = [binary_to_path(X, "lib/elixir/ebin") || X <- Lists],
    io:format("Compiled ~ts~n", [File])
  catch
    Kind:Reason ->
@@ -0,0 +1,65 @@
+-module(elixir_config).
+-compile({no_auto_import, [get/1]}).
+-export([new/1, delete/1, put/2, get/1, update/2, get_and_put/2]).
+-export([start_link/0, init/1, handle_call/3, handle_cast/2,
+  handle_info/2, code_change/3, terminate/2]).
+-behaviour(gen_server).
+
+%% public api
+
+new(Opts) ->
+  Tab = ets:new(?MODULE, [named_table, public, {read_concurrency, true}]),
+  true = ets:insert_new(?MODULE, Opts),
+  Tab.
+
+delete(?MODULE) ->
+  ets:delete(?MODULE).
+
+put(Key, Value) ->
+  gen_server:call(?MODULE, {put, Key, Value}).
+
+get(Key) ->
+  case ets:lookup(?MODULE, Key) of
+    [{_, Value}] -> Value;
+    []          -> nil
+  end.
+
+update(Key, Fun) ->
+  gen_server:call(?MODULE, {update, Key, Fun}).
+
+get_and_put(Key, Value) ->
+  gen_server:call(?MODULE, {get_and_put, Key, Value}).
+
+start_link() ->
+  gen_server:start_link({local, ?MODULE}, ?MODULE, ?MODULE, []).
+
+%% gen_server api
+
+init(Tab) ->
+  %% Ets table must be writable
+  public = ets:info(Tab, protection),
+  {ok, Tab}.
+
+handle_call({put, Key, Value}, _From, Tab) ->
+  ets:insert(Tab, {Key, Value}),
+  {reply, ok, Tab};
+handle_call({update, Key, Fun}, _From, Tab) ->
+  Value = Fun(get(Key)),
+  ets:insert(Tab, {Key, Value}),
+  {reply, Value, Tab};
+handle_call({get_and_put, Key, Value}, _From, Tab) ->
+  OldValue = get(Key),
+  ets:insert(Tab, {Key, Value}),
+  {reply, OldValue, Tab}.
+
+handle_cast(Cast, Tab) ->
+  {stop, {bad_cast, Cast}, Tab}.
+
+handle_info(_Msg, Tab) ->
+  {noreply, Tab}.
+
+code_change(_OldVsn, Tab, _Extra) ->
+  {ok, Tab}.
+
+terminate(_Reason, _Tab) ->
+  ok.
@@ -3,8 +3,8 @@
  handle_info/2, terminate/2, code_change/3, next/0]).
 -behaviour(gen_server).

-define(timeout, 1000).     %% 1 second
-define(limit, 4294967296). %% 2^32
+-define(timeout, 30000).    %% 30 seconds
+-define(limit, 4294967295). %% 2^32 - 1

 next() ->
  gen_server:call(?MODULE, next, ?timeout).
@@ -1,49 +1,35 @@
 % Holds the logic responsible for function definitions (def(p) and defmacro(p)).
 -module(elixir_def).
-export([table/1, clauses_table/1, setup/1,
-  cleanup/1, reset_last/1, lookup_definition/2,
-  delete_definition/2, store_definition/6, unwrap_definitions/1,
-  store_each/8, format_error/1]).
+-export([setup/1, reset_last/1, lookup_definition/2,
+  delete_definition/2, store_definition/6, unwrap_definitions/2,
+  store_each/7, format_error/1]).
 -include("elixir.hrl").

-define(attr, '__def_table').
-define(clauses_attr, '__clauses_table').
+-define(last_def, {elixir, last_def}).
+-define(attr, {elixir, def_table}).
+-define(clauses_attr, {elixir, clauses_table}).

 %% Table management functions. Called internally.

-table(Module) ->
-  ets:lookup_element(Module, ?attr, 2).
-
-clauses_table(Module) ->
-  ets:lookup_element(Module, ?clauses_attr, 2).
-
 setup(Module) ->
-  ets:insert(Module, {?attr, ets:new(Module, [set, public])}),
-  ets:insert(Module, {?clauses_attr, ets:new(Module, [bag, public])}),
  reset_last(Module),
  ok.

-cleanup(Module) ->
-  ets:delete(table(Module)),
-  ets:delete(clauses_table(Module)).
-
-%% Reset the last item. Useful when evaling code.
 reset_last(Module) ->
-  ets:insert(table(Module), {last, []}).
+  ets:insert(elixir_module:data_table(Module), {?last_def, []}).

-%% Looks up a definition from the database.
 lookup_definition(Module, Tuple) ->
-  case ets:lookup(table(Module), Tuple) of
+  case ets:lookup(elixir_module:defs_table(Module), Tuple) of
    [Result] ->
-      CTable = clauses_table(Module),
+      CTable = elixir_module:clas_table(Module),
      {Result, [Clause || {_, Clause} <- ets:lookup(CTable, Tuple)]};
    _ ->
      false
  end.

 delete_definition(Module, Tuple) ->
-  ets:delete(table(Module), Tuple),
-  ets:delete(clauses_table(Module), Tuple).
+  ets:delete(elixir_module:defs_table(Module), Tuple),
+  ets:delete(elixir_module:clas_table(Module), Tuple).

 % Invoked by the wrap definition with the function abstract tree.
 % Each function is then added to the function table.
@@ -55,7 +41,7 @@ store_definition(Line, Kind, CheckClauses, Call, Body, Pos) ->
  {Name, Args} = case NameAndArgs of
    {N, _, A} when is_atom(N), is_atom(A) -> {N, []};
    {N, _, A} when is_atom(N), is_list(A) -> {N, A};
-    _ -> elixir_errors:form_error(Line, ?m(E, file), ?MODULE, {invalid_def, Kind, NameAndArgs})
+    _ -> elixir_errors:form_error([{line, Line}], ?m(E, file), ?MODULE, {invalid_def, Kind, NameAndArgs})
  end,

  %% Now that we have verified the call format,
@@ -64,11 +50,17 @@ store_definition(Line, Kind, CheckClauses, Call, Body, Pos) ->
  DoCheckClauses = (not lists:keymember(context, 1, Meta)) andalso (CheckClauses),

  %% Check if there is a file information in the definition.
-  %% If so, we assume this come from another source and we need
-  %% to linify taking into account keep line numbers.
-  {File, Key}  = case lists:keyfind(file, 1, Meta) of
-    {file, Bin} when is_binary(Bin) -> {Bin, keep};
-    _ -> {nil, line}
+  %% If so, we assume this come from another source and
+  %% we need to linify taking into account keep line numbers.
+  {Location, Key} = case lists:keyfind(file, 1, Meta) of
+    {file, KeepFile} when is_binary(KeepFile) ->
+      case lists:keyfind(keep, 1, Meta) of
+        {keep, KeepLine} when is_integer(KeepLine) -> KeepLine;
+        _ -> KeepLine = 0
+      end,
+      {{KeepFile, KeepLine}, keep};
+    _ ->
+      {nil, line}
  end,

  LinifyArgs   = elixir_quote:linify(Line, Key, Args),
@@ -76,31 +68,28 @@ store_definition(Line, Kind, CheckClauses, Call, Body, Pos) ->
  LinifyBody   = elixir_quote:linify(Line, Key, Body),

  assert_no_aliases_name(Line, Name, Args, E),
+  assert_valid_name(Line, Kind, Name, Args, E),
  store_definition(Line, Kind, DoCheckClauses, Name,
-                   LinifyArgs, LinifyGuards, LinifyBody, File, E).
+                   LinifyArgs, LinifyGuards, LinifyBody, Location, E).

-store_definition(Line, Kind, CheckClauses, Name, Args, Guards, Body, MetaFile, #{module := Module} = ER) ->
+store_definition(Line, Kind, CheckClauses, Name, Args, Guards, Body, KeepLocation, #{module := Module} = ER) ->
  Arity = length(Args),
  Tuple = {Name, Arity},
  E = ER#{function := Tuple},
  elixir_locals:record_definition(Tuple, Kind, Module),

-  Location = retrieve_location(Line, MetaFile, Module),
+  Location = retrieve_location(KeepLocation, Module),
  {Function, Defaults, Super} = translate_definition(Kind, Line, Module, Name, Args, Guards, Body, E),

  DefaultsLength = length(Defaults),
  elixir_locals:record_defaults(Tuple, Kind, Module, DefaultsLength),

  File = ?m(E, file),
-  Table  = table(Module),
-  CTable = clauses_table(Module),
-
  compile_super(Module, Super, E),
-  check_previous_defaults(Table, Line, Name, Arity, Kind, DefaultsLength, E),
+  check_previous_defaults(Line, Module, Name, Arity, Kind, DefaultsLength, E),

-  store_each(CheckClauses, Kind, File, Location,
-    Table, CTable, DefaultsLength, Function),
-  [store_each(false, Kind, File, Location, Table, CTable, 0,
+  store_each(CheckClauses, Kind, File, Location, Module, DefaultsLength, Function),
+  [store_each(false, Kind, File, Location, Module, 0,
    default_function_for(Kind, Name, Default)) || Default <- Defaults],

  make_struct_available(Kind, Module, Name, Args),
@@ -115,31 +104,36 @@ run_on_definition_callbacks(Kind, Line, Module, Name, Args, Guards, Expr, E) ->
    _ ->
      Env = elixir_env:linify({Line, E}),
      Callbacks = 'Elixir.Module':get_attribute(Module, on_definition),
-      [Mod:Fun(Env, Kind, Name, Args, Guards, Expr) || {Mod, Fun} <- Callbacks]
+      _ = [Mod:Fun(Env, Kind, Name, Args, Guards, Expr) || {Mod, Fun} <- Callbacks],
+      ok
  end.

 make_struct_available(def, Module, '__struct__', []) ->
  case erlang:get(elixir_compiler_pid) of
    undefined -> ok;
-    Pid -> Pid ! {struct_available, Module}
+    Pid ->
+      Pid ! {struct_available, Module},
+      ok
  end;
 make_struct_available(_, _, _, _) ->
  ok.

-%% Retrieve location from meta file or @file, otherwise nil
+%% Retrieve location from meta file (if Key == keep)
+%% or @file, otherwise nil

-retrieve_location(Line, File, Module) ->
+retrieve_location(Location, Module) ->
  case get_location_attribute(Module) of
-    nil when not is_binary(File) ->
-      nil;
-    nil ->
+    nil when is_tuple(Location) ->
+      {File, Line} = Location,
      {normalize_location(File), Line};
-    X when is_binary(X) ->
+    nil ->
+      nil;
+    File when is_binary(File) ->
      'Elixir.Module':delete_attribute(Module, file),
-      {normalize_location(X), 0};
-    {X, L} when is_binary(X) andalso is_integer(L) ->
+      {normalize_location(File), 0};
+    {File, Line} when is_binary(File) andalso is_integer(Line) ->
      'Elixir.Module':delete_attribute(Module, file),
-      {normalize_location(X), L}
+      {normalize_location(File), Line}
  end.

 get_location_attribute(Module) ->
@@ -148,13 +142,13 @@ get_location_attribute(Module) ->
    false -> 'Elixir.Module':get_attribute(Module, file)
  end.

-normalize_location(X) ->
-  elixir_utils:characters_to_list(elixir_utils:relative_to_cwd(X)).
+normalize_location(File) ->
+  elixir_utils:characters_to_list(elixir_utils:relative_to_cwd(File)).

 %% Compile super

 compile_super(Module, true, #{function := Function}) ->
-  elixir_def_overridable:store(Module, Function, true);
+  elixir_def_overridable:super(Module, Function);
 compile_super(_Module, _, _E) -> ok.

 %% Translate the given call and expression given
@@ -179,7 +173,7 @@ translate_definition(Kind, Line, Module, Name, Args, Guards, Body, E) when is_in
 translate_clause(nil, _Line, _Kind, _Args, [], _Body, _S) ->
  {[], false};
 translate_clause(nil, Line, Kind, _Args, _Guards, _Body, #elixir_scope{file=File}) ->
-  elixir_errors:form_error(Line, File, ?MODULE, {missing_do, Kind});
+  elixir_errors:form_error([{line, Line}], File, ?MODULE, {missing_do, Kind});
 translate_clause(_, Line, Kind, Args, Guards, Body, S) ->
  {TClause, TS} = elixir_clauses:clause(Line,
    fun elixir_translator:translate_args/2, Args, Body, Guards, true, S),
@@ -216,120 +210,167 @@ is_macro(_)         -> false.
 % Unwrap the functions stored in the functions table.
 % It returns a list of all functions to be exported, plus the macros,
 % and the body of all functions.
-unwrap_definitions(Module) ->
-  Table = table(Module),
-  CTable = clauses_table(Module),
-  ets:delete(Table, last),
-  unwrap_definition(ets:tab2list(Table), CTable, [], [], [], [], [], [], []).
+unwrap_definitions(File, Module) ->
+  Table  = elixir_module:defs_table(Module),
+  CTable = elixir_module:clas_table(Module),

-unwrap_definition([Fun|T], CTable, All, Exports, Private, Def, Defmacro, Functions, Tail) ->
-  Tuple   = element(1, Fun),
-  Clauses = [Clause || {_, Clause} <- ets:lookup(CTable, Tuple)],
+  {All, Private} = unwrap_definition(ets:tab2list(Table), File, Module, CTable, [], []),
+  Unreachable = elixir_locals:warn_unused_local(File, Module, Private),
+  split_definition(All, Unreachable, [], [], [], [], [], {[], []}).

-  {NewFun, NewExports, NewPrivate, NewDef, NewDefmacro} =
-    case Clauses of
-      [] -> {false, Exports, Private, Def, Defmacro};
-      _  -> unwrap_definition(element(2, Fun), Tuple, Fun, Exports, Private, Def, Defmacro)
+unwrap_definition([Fun|T], File, Module, CTable, All, Private) ->
+  {Tuple, Kind, Line, _, Check, Location, {Defaults, _, _}} = Fun,
+  Export = export(Kind, Tuple),
+
+  case [Clause || {_, Clause} <- ets:lookup(CTable, Tuple)] of
+    [] ->
+      warn_bodyless_function(Line, File, Module, Kind, Tuple),
+      unwrap_definition(T, File, Module, CTable, All, Private);
+    Clauses ->
+      Unwrapped = {Tuple, Kind, Line, Location,
+                   function_for_stored_definition(Line, Export, Clauses)},
+
+      NewPrivate =
+        if
+          Kind == defp; Kind == defmacrop ->
+            [{Tuple, Kind, Line, Check, Defaults}|Private];
+          true ->
+            Private
        end,

-  {NewFunctions, NewTail} = case NewFun of
+      unwrap_definition(T, File, Module, CTable, [Unwrapped|All], NewPrivate)
+  end;
+
+unwrap_definition([], _File, _Module, _CTable, All, Private) ->
+  {All, Private}.
+
+split_definition([{Tuple, def, Line, Location, Body}|T], Unreachable,
+                 Def, Defp, Defmacro, Defmacrop, Exports, Functions) ->
+  split_definition(T, Unreachable, [Tuple|Def], Defp, Defmacro, Defmacrop,
+                   [export(def, Tuple)|Exports],
+                   add_definition(Line, Location, Body, Functions));
+
+split_definition([{Tuple, defp, Line, Location, Body}|T], Unreachable,
+                 Def, Defp, Defmacro, Defmacrop, Exports, Functions) ->
+  case lists:member(Tuple, Unreachable) of
    false ->
-      NewAll = All,
-      {Functions, Tail};
-    _ ->
-      NewAll = [Tuple|All],
-      function_for_stored_definition(NewFun, Clauses, Functions, Tail)
-  end,
+      split_definition(T, Unreachable, Def, [Tuple|Defp], Defmacro, Defmacrop,
+                       Exports, add_definition(Line, Location, Body, Functions));
+    true ->
+      split_definition(T, Unreachable, Def, [Tuple|Defp], Defmacro, Defmacrop,
+                       Exports, Functions)
+  end;

-  unwrap_definition(T, CTable, NewAll, NewExports, NewPrivate,
-    NewDef, NewDefmacro, NewFunctions, NewTail);
-unwrap_definition([], _CTable, All, Exports, Private, Def, Defmacro, Functions, Tail) ->
-  {All, Exports, Private, ordsets:from_list(Def),
-    ordsets:from_list(Defmacro), lists:reverse(Tail ++ Functions)}.
+split_definition([{Tuple, defmacro, Line, Location, Body}|T], Unreachable,
+                 Def, Defp, Defmacro, Defmacrop, Exports, Functions) ->
+  split_definition(T, Unreachable, Def, Defp, [Tuple|Defmacro], Defmacrop,
+                   [export(defmacro, Tuple)|Exports],
+                   add_definition(Line, Location, Body, Functions));

-unwrap_definition(def, Tuple, Fun, Exports, Private, Def, Defmacro) ->
-  {Fun, [Tuple|Exports], Private, [Tuple|Def], Defmacro};
-unwrap_definition(defmacro, {Name, Arity} = Tuple, Fun, Exports, Private, Def, Defmacro) ->
-  Macro = {elixir_utils:macro_name(Name), Arity + 1},
-  {setelement(1, Fun, Macro), [Macro|Exports], Private, Def, [Tuple|Defmacro]};
-unwrap_definition(defp, Tuple, Fun, Exports, Private, Def, Defmacro) ->
-  %% {Name, Arity}, Kind, Line, Check, Defaults
-  Info = {Tuple, defp, element(3, Fun), element(5, Fun), element(7, Fun)},
-  {Fun, Exports, [Info|Private], Def, Defmacro};
-unwrap_definition(defmacrop, Tuple, Fun, Exports, Private, Def, Defmacro) ->
-  %% {Name, Arity}, Kind, Line, Check, Defaults
-  Info  = {Tuple, defmacrop, element(3, Fun), element(5, Fun), element(7, Fun)},
-  {false, Exports, [Info|Private], Def, Defmacro}.
+split_definition([{Tuple, defmacrop, _Line, _Location, _Body}|T], Unreachable,
+                 Def, Defp, Defmacro, Defmacrop, Exports, Functions) ->
+  split_definition(T, Unreachable, Def, Defp, Defmacro, [Tuple|Defmacrop],
+                   Exports, Functions);
+
+split_definition([], _Unreachable, Def, Defp, Defmacro, Defmacrop, Exports, {Head, Tail}) ->
+  {Def, Defp, Defmacro, Defmacrop, Exports, Head ++ Tail}.

 %% Helpers

-function_for_stored_definition({{Name,Arity}, _, Line, _, _, nil, _}, Clauses, Functions, Tail) ->
-  {[{function, Line, Name, Arity, Clauses}|Functions], Tail};
+export(Kind, {Name, Arity}) when Kind == defmacro; Kind == defmacrop ->
+  {elixir_utils:macro_name(Name), Arity + 1};
+export(Kind, {Name, Arity}) when Kind == def; Kind == defp ->
+  {Name, Arity}.

-function_for_stored_definition({{Name,Arity}, _, Line, _, _, Location, _}, Clauses, Functions, Tail) ->
-  {Functions, [
-    {function, Line, Name, Arity, Clauses},
-    {attribute, Line, file, Location} | Tail
-  ]}.
+function_for_stored_definition(Line, {Name,Arity}, Clauses) ->
+  {function, Line, Name, Arity, Clauses}.
+
+add_definition(_Line, nil, Body, {Head, Tail}) ->
+  {[Body|Head], Tail};
+add_definition(Line, Location, Body, {Head, Tail}) ->
+  {Head,
+   [{attribute, Line, file, Location}, Body|Tail]}.

 default_function_for(Kind, Name, {clause, Line, Args, _Guards, _Exprs} = Clause)
    when Kind == defmacro; Kind == defmacrop ->
  {function, Line, Name, length(Args) - 1, [Clause]};
-
 default_function_for(_, Name, {clause, Line, Args, _Guards, _Exprs} = Clause) ->
  {function, Line, Name, length(Args), [Clause]}.

+warn_bodyless_function(_Line, _File, Special, _Kind, _Tuple)
+    when Special == 'Elixir.Kernel.SpecialForms'; Special == 'Elixir.Module' ->
+  ok;
+warn_bodyless_function(Line, File, _Module, Kind, Tuple) ->
+  elixir_errors:form_warn([{line, Line}], File, ?MODULE, {bodyless_fun, Kind, Tuple}),
+  ok.
+
 %% Store each definition in the table.
 %% This function also checks and emit warnings in case
 %% the kind, of the visibility of the function changes.

-store_each(Check, Kind, File, Location, Table, CTable, Defaults, {function, Line, Name, Arity, Clauses}) ->
+store_each(Check, Kind, File, Location, Module, Defaults, {function, Line, Name, Arity, Clauses}) ->
+  Data = elixir_module:data_table(Module),
+  Defs = elixir_module:defs_table(Module),
+  Clas = elixir_module:clas_table(Module),
+
  Tuple   = {Name, Arity},
-  case ets:lookup(Table, Tuple) of
-    [{Tuple, StoredKind, StoredLine, StoredFile, StoredCheck, StoredLocation, StoredDefaults}] ->
+  HasBody = Clauses =/= [],
+
+  case ets:lookup(Defs, Tuple) of
+    [{Tuple, StoredKind, StoredLine, StoredFile, StoredCheck,
+        StoredLocation, {StoredDefaults, LastHasBody, LastDefaults}}] ->
      FinalLine = StoredLine,
      FinalLocation = StoredLocation,
-      FinalDefaults = max(Defaults, StoredDefaults),
+      FinalDefaults = {max(Defaults, StoredDefaults), HasBody, Defaults},
      check_valid_kind(Line, File, Name, Arity, Kind, StoredKind),
      (Check and StoredCheck) andalso
-        check_valid_clause(Line, File, Name, Arity, Kind, Table, StoredLine, StoredFile),
-      check_valid_defaults(Line, File, Name, Arity, Kind, Defaults, StoredDefaults);
+        check_valid_clause(Line, File, Name, Arity, Kind, Data, StoredLine, StoredFile),
+      check_valid_defaults(Line, File, Name, Arity, Kind, Defaults, LastDefaults, LastHasBody);
    [] ->
      FinalLine = Line,
      FinalLocation = Location,
-      FinalDefaults = Defaults
+      FinalDefaults = {Defaults, HasBody, Defaults}
  end,
-  Check andalso ets:insert(Table, {last, {Name, Arity}}),
-  ets:insert(CTable, [{Tuple, Clause} || Clause <- Clauses ]),
-  ets:insert(Table, {Tuple, Kind, FinalLine, File, Check, FinalLocation, FinalDefaults}).
+
+  Check andalso ets:insert(Data, {?last_def, {Name, Arity}}),
+  ets:insert(Clas, [{Tuple, Clause} || Clause <- Clauses]),
+  ets:insert(Defs, {Tuple, Kind, FinalLine, File, Check, FinalLocation, FinalDefaults}).

 %% Validations

 check_valid_kind(_Line, _File, _Name, _Arity, Kind, Kind) -> [];
 check_valid_kind(Line, File, Name, Arity, Kind, StoredKind) ->
-  elixir_errors:form_error(Line, File, ?MODULE,
+  elixir_errors:form_error([{line, Line}], File, ?MODULE,
    {changed_kind, {Name, Arity, StoredKind, Kind}}).

-check_valid_clause(Line, File, Name, Arity, Kind, Table, StoredLine, StoredFile) ->
-  case ets:lookup_element(Table, last, 2) of
+check_valid_clause(Line, File, Name, Arity, Kind, Data, StoredLine, StoredFile) ->
+  case ets:lookup_element(Data, ?last_def, 2) of
    {Name,Arity} -> [];
    [] -> [];
    _ ->
-      Relative = elixir_utils:relative_to_cwd(StoredFile),
-      elixir_errors:handle_file_warning(File, {Line, ?MODULE,
-        {ungrouped_clause, {Kind, Name, Arity, StoredLine, Relative}}})
+      Relative = elixir_utils:relative_to_cwd(elixir_utils:relative_to_cwd(StoredFile)),
+      elixir_errors:form_warn([{line, Line}], File, ?MODULE,
+        {ungrouped_clause, {Kind, Name, Arity, StoredLine, Relative}})
  end.

-check_valid_defaults(_Line, _File, _Name, _Arity, _Kind, 0, _) -> [];
-check_valid_defaults(Line, File, Name, Arity, Kind, _, 0) ->
-  elixir_errors:handle_file_warning(File, {Line, ?MODULE, {out_of_order_defaults, {Kind, Name, Arity}}});
-check_valid_defaults(Line, File, Name, Arity, Kind, _, _) ->
-  elixir_errors:form_error(Line, File, ?MODULE, {clauses_with_defaults, {Kind, Name, Arity}}).
+% Any clause after clause with defaults (body less does not count)
+check_valid_defaults(Line, File, Name, Arity, Kind, _, StoredDefaults, true) when StoredDefaults > 0 ->
+  elixir_errors:form_error([{line, Line}], File, ?MODULE,
+    {clauses_with_defaults, {Kind, Name, Arity}});
+% Clause without defaults
+check_valid_defaults(_Line, _File, _Name, _Arity, _Kind, 0, _, _) -> [];
+% Clause with defaults after clause without defaults
+check_valid_defaults(Line, File, Name, Arity, Kind, _, 0, _) ->
+  elixir_errors:form_warn([{line, Line}], File, ?MODULE, {out_of_order_defaults, {Kind, Name, Arity}});
+% Clause with defaults after clause with defaults
+check_valid_defaults(Line, File, Name, Arity, Kind, _, _, _) ->
+  elixir_errors:form_error([{line, Line}], File, ?MODULE,
+    {clauses_with_defaults, {Kind, Name, Arity}}).

-check_previous_defaults(Table, Line, Name, Arity, Kind, Defaults, E) ->
-  Matches = ets:match(Table, {{Name, '$2'}, '$1', '_', '_', '_', '_', '$3'}),
+check_previous_defaults(Line, Module, Name, Arity, Kind, Defaults, E) ->
+  Matches = ets:match(elixir_module:defs_table(Module), {{Name, '$2'}, '$1', '_', '_', '_', '_', {'$3', '_', '_'}}),
  [ begin
-      elixir_errors:form_error(Line, ?m(E, file), ?MODULE,
+      elixir_errors:form_error([{line, Line}], ?m(E, file), ?MODULE,
        {defs_with_defaults, Name, {Kind, Arity}, {K, A}})
    end || [K, A, D] <- Matches, A /= Arity, D /= 0, defaults_conflict(A, D, Arity, Defaults)].

@@ -339,7 +380,8 @@ defaults_conflict(A, D, Arity, Defaults) ->

 check_args_for_bodyless_clause(Line, Args, E) ->
  [ begin
-      elixir_errors:form_error(Line, ?m(E, file), ?MODULE, invalid_args_for_bodyless_clause)
+      elixir_errors:form_error([{line, Line}], ?m(E, file), ?MODULE,
+        invalid_args_for_bodyless_clause)
    end || Arg <- Args, invalid_arg(Arg) ].

 invalid_arg({Name, _, Kind}) when is_atom(Name), is_atom(Kind) ->
@@ -350,13 +392,20 @@ invalid_arg(_) ->
  true.

 assert_no_aliases_name(Line, '__aliases__', [Atom], #{file := File}) when is_atom(Atom) ->
-  elixir_errors:form_error(Line, File, ?MODULE, {no_alias, Atom});
+  elixir_errors:form_error([{line, Line}], File, ?MODULE, {no_alias, Atom});
+assert_no_aliases_name(_Line, _Aliases, _Args, _S) ->
+  ok.

-assert_no_aliases_name(_Meta, _Aliases, _Args, _S) ->
+assert_valid_name(Line, Kind, is_record, [_, _], #{file := File}) when Kind == defp; Kind == def ->
+  elixir_errors:form_error([{line, Line}], File, ?MODULE, {is_record, Kind});
+assert_valid_name(_Line, _Kind, _Name, _Args, _S) ->
  ok.

 %% Format errors

+format_error({bodyless_fun, Kind, {Name, Arity}}) ->
+  io_lib:format("bodyless clause provided for nonexistent ~ts ~ts/~B", [Kind, Name, Arity]);
+
 format_error({no_module,{Kind,Name,Arity}}) ->
  io_lib:format("cannot define function outside module, invalid scope for ~ts ~ts/~B", [Kind, Name, Arity]);

@@ -391,5 +440,9 @@ format_error({invalid_def, Kind, NameAndArgs}) ->
 format_error(invalid_args_for_bodyless_clause) ->
  "can use only variables and \\\\ as arguments of bodyless clause";

+format_error({is_record, Kind}) ->
+  io_lib:format("cannot define function named ~ts is_record/2 due to compability "
+                "issues with the Erlang compiler (it is a known bug)", [Kind]);
+
 format_error({missing_do, Kind}) ->
  io_lib:format("missing do keyword in ~ts", [Kind]).
@@ -4,10 +4,11 @@
 -include("elixir.hrl").

 expand(Args, E) ->
+  NoContext = E#{context := nil},
  lists:mapfoldl(fun
    ({'\\\\', Meta, [Left, Right]}, Acc) ->
      {ELeft, EL} = elixir_exp:expand(Left, Acc),
-      {ERight, _} = elixir_exp:expand(Right, Acc#{context := nil}),
+      {ERight, _} = elixir_exp:expand(Right, NoContext),
      {{'\\\\', Meta, [ELeft, ERight]}, EL};
    (Left, Acc) ->
      elixir_exp:expand(Left, Acc)
@@ -1,14 +1,18 @@
 % Holds the logic responsible for defining overridable functions and handling super.
 -module(elixir_def_overridable).
-export([store_pending/1, ensure_defined/4,
-  name/2, store/3, format_error/1]).
+-export([setup/1, overridable/1, overridable/2, name/2, super/2, store_pending/1,
+         ensure_defined/4, format_error/1]).
 -include("elixir.hrl").
+-define(attr, {elixir, overridable}).
+
+setup(Module) ->
+  overridable(Module, []).

 overridable(Module) ->
-  ets:lookup_element(elixir_module:data_table(Module), '__overridable', 2).
+  ets:lookup_element(elixir_module:data_table(Module), ?attr, 2).

 overridable(Module, Value) ->
-  ets:insert(elixir_module:data_table(Module), {'__overridable', Value}).
+  ets:insert(elixir_module:data_table(Module), {?attr, Value}).

 %% Check if an overridable function is defined.

@@ -36,30 +40,31 @@ store(Module, Function, GenerateName) ->
    {_Count, _Clause, _Neighbours, true} -> ok;
    {Count, Clause, Neighbours, false} ->
      overridable(Module, orddict:store(Function, {Count, Clause, Neighbours, true}, Overridable)),
-      {{{Name, Arity}, Kind, Line, File, _Check, Location, Defaults}, Clauses} = Clause,
+      {{{Name, Arity}, Kind, Line, File, _Check, Location, {Defaults, _HasBody, _LastDefaults}}, Clauses} = Clause,

      {FinalKind, FinalName} = case GenerateName of
        true  -> {defp, name(Module, Function, Overridable)};
        false -> {Kind, Name}
      end,

-      case code:is_loaded('Elixir.Module.LocalsTracker') of
-        {_, _} ->
+      case elixir_compiler:get_opt(internal) of
+        false ->
          'Elixir.Module.LocalsTracker':reattach(Module, Kind, {Name, Arity}, Neighbours);
-        _ ->
+        true ->
          ok
      end,

      Def = {function, Line, FinalName, Arity, Clauses},
-      elixir_def:store_each(false, FinalKind, File, Location,
-        elixir_def:table(Module), elixir_def:clauses_table(Module), Defaults, Def)
+      elixir_def:store_each(false, FinalKind, File, Location, Module, Defaults, Def)
  end.

-%% Store pending declarations that were not manually made concrete.
+super(Module, Function) ->
+  store(Module, Function, true).

 store_pending(Module) ->
-  [store(Module, X, false) || {X, {_, _, _, false}} <- overridable(Module),
-    not 'Elixir.Module':'defines?'(Module, X)].
+  _ = [store(Module, X, false) || {X, {_, _, _, false}} <- overridable(Module),
+    not 'Elixir.Module':'defines?'(Module, X)],
+  ok.

 %% Error handling

@@ -4,24 +4,12 @@
 -module(elixir_dispatch).
 -export([dispatch_import/5, dispatch_require/6,
  require_function/5, import_function/4,
-  expand_import/5, expand_require/5,
+  expand_import/6, expand_require/5,
  default_functions/0, default_macros/0, default_requires/0,
  find_import/4, format_error/1]).
 -include("elixir.hrl").
 -import(ordsets, [is_element/2]).
-
-define(atom, 'Elixir.Atom').
-define(float, 'Elixir.Float').
-define(io, 'Elixir.IO').
-define(integer, 'Elixir.Integer').
 -define(kernel, 'Elixir.Kernel').
-define(list, 'Elixir.List').
-define(map, 'Elixir.Map').
-define(node, 'Elixir.Node').
-define(process, 'Elixir.Process').
-define(string, 'Elixir.String').
-define(system, 'Elixir.System').
-define(tuple, 'Elixir.Tuple').

 default_functions() ->
  [{?kernel, elixir_imported_functions()}].
@@ -30,17 +18,20 @@ default_macros() ->
 default_requires() ->
  ['Elixir.Kernel', 'Elixir.Kernel.Typespec'].

+%% This is used by elixir_quote. Note we don't record the
+%% import locally because at that point there is no
+%% ambiguity.
 find_import(Meta, Name, Arity, E) ->
  Tuple = {Name, Arity},

  case find_dispatch(Meta, Tuple, [], E) of
    {function, Receiver} ->
      elixir_lexical:record_import(Receiver, ?m(E, lexical_tracker)),
-      elixir_locals:record_import(Tuple, Receiver, ?m(E, module), ?m(E, function)),
+      %% elixir_locals:record_import(Tuple, Receiver, ?m(E, module), ?m(E, function)),
      Receiver;
    {macro, Receiver} ->
      elixir_lexical:record_import(Receiver, ?m(E, lexical_tracker)),
-      elixir_locals:record_import(Tuple, Receiver, ?m(E, module), ?m(E, function)),
+      %% elixir_locals:record_import(Tuple, Receiver, ?m(E, module), ?m(E, function)),
      Receiver;
    _ ->
      false
@@ -78,7 +69,7 @@ remote_function(Meta, Receiver, Name, Arity, E) ->
  check_deprecation(Meta, Receiver, Name, Arity, E),

  elixir_lexical:record_remote(Receiver, ?m(E, lexical_tracker)),
-  case inline(Receiver, Name, Arity) of
+  case elixir_rewrite:inline(Receiver, Name, Arity) of
    {AR, AN} -> {remote, AR, AN, Arity};
    false    -> {remote, Receiver, Name, Arity}
  end.
@@ -87,7 +78,7 @@ remote_function(Meta, Receiver, Name, Arity, E) ->

 dispatch_import(Meta, Name, Args, E, Callback) ->
  Arity = length(Args),
-  case expand_import(Meta, {Name, Arity}, Args, E, []) of
+  case expand_import(Meta, {Name, Arity}, Args, E, [], false) of
    {ok, Receiver, Quoted} ->
      expand_quoted(Meta, Receiver, Name, Arity, Quoted, E);
    {ok, Receiver, NewName, NewArgs} ->
@@ -99,9 +90,9 @@ dispatch_import(Meta, Name, Args, E, Callback) ->
 dispatch_require(Meta, Receiver, Name, Args, E, Callback) when is_atom(Receiver) ->
  Arity = length(Args),

-  case rewrite(Receiver, Name, Args, Arity) of
-    {ok, AR, AN, AA} ->
-      Callback(AR, AN, AA);
+  case elixir_rewrite:inline(Receiver, Name, Arity) of
+    {AR, AN} ->
+      Callback(AR, AN, Args);
    false ->
      case expand_require(Meta, Receiver, {Name, Arity}, Args, E) of
        {ok, Receiver, Quoted} -> expand_quoted(Meta, Receiver, Name, Arity, Quoted, E);
@@ -114,12 +105,12 @@ dispatch_require(_Meta, Receiver, Name, Args, _E, Callback) ->

 %% Macros expansion

-expand_import(Meta, {Name, Arity} = Tuple, Args, E, Extra) ->
+expand_import(Meta, {Name, Arity} = Tuple, Args, E, Extra, External) ->
  Module      = ?m(E, module),
  Dispatch    = find_dispatch(Meta, Tuple, Extra, E),
  Function    = ?m(E, function),
-  Local    = (Function /= nil) andalso (Function /= Tuple) andalso
-              elixir_locals:macro_for(Module, Name, Arity),
+  AllowLocals = External orelse ((Function /= nil) andalso (Function /= Tuple)),
+  Local       = AllowLocals andalso elixir_locals:macro_for(Module, Name, Arity),

  case Dispatch of
    %% In case it is an import, we dispatch the import.
@@ -147,11 +138,7 @@ do_expand_import(Meta, {Name, Arity} = Tuple, Args, Module, E, Result) ->
    {function, Receiver} ->
      elixir_lexical:record_import(Receiver, ?m(E, lexical_tracker)),
      elixir_locals:record_import(Tuple, Receiver, Module, ?m(E, function)),
-
-      case rewrite(Receiver, Name, Args, Arity) of
-        {ok, _, _, _} = Res -> Res;
-        false -> {ok, Receiver, Name, Args}
-      end;
+      {ok, Receiver, Name, Args};
    {macro, Receiver} ->
      check_deprecation(Meta, Receiver, Name, Arity, E),
      elixir_lexical:record_import(Receiver, ?m(E, lexical_tracker)),
@@ -163,8 +150,8 @@ do_expand_import(Meta, {Name, Arity} = Tuple, Args, Module, E, Result) ->
        error -> {ok, Receiver, Name, Args}
      end;
    false when Module == ?kernel ->
-      case rewrite(Module, Name, Args, Arity) of
-        {ok, _, _, _} = Res -> Res;
+      case elixir_rewrite:inline(Module, Name, Arity) of
+        {AR, AN} -> {ok, AR, AN, Args};
        false -> error
      end;
    false ->
@@ -228,7 +215,7 @@ expand_quoted(Meta, Receiver, Name, Arity, Quoted, E) ->
  end.

 caller(Line, #{module := nil} = E) ->
-  {elixir_compiler, '__FILE__', 2, location(Line, E)};
+  {elixir_compiler_0, '__FILE__', 1, location(Line, E)};
 caller(Line, #{module := Module, function := nil} = E) ->
  {Module, '__MODULE__', 0, location(Line, E)};
 caller(Line, #{module := Module, function := {Name, Arity}} = E) ->
@@ -338,152 +325,6 @@ elixir_imported_macros() ->
    error:undef -> []
  end.

-rewrite(?atom, to_string, [Arg], _) ->
-  {ok, erlang, atom_to_binary, [Arg, utf8]};
-rewrite(?kernel, elem, [Tuple, Index], _) ->
-  {ok, erlang, element, [increment(Index), Tuple]};
-rewrite(?kernel, put_elem, [Tuple, Index, Value], _) ->
-  {ok, erlang, setelement, [increment(Index), Tuple, Value]};
-rewrite(?map, 'has_key?', [Map, Key], _) ->
-  {ok, maps, is_key, [Key, Map]};
-rewrite(?map, fetch, [Map, Key], _) ->
-  {ok, maps, find, [Key, Map]};
-rewrite(?map, put, [Map, Key, Value], _) ->
-  {ok, maps, put, [Key, Value, Map]};
-rewrite(?map, delete, [Map, Key], _) ->
-  {ok, maps, remove, [Key, Map]};
-rewrite(?process, monitor, [Arg], _) ->
-  {ok, erlang, monitor, [process, Arg]};
-rewrite(?string, to_atom, [Arg], _) ->
-  {ok, erlang, binary_to_atom, [Arg, utf8]};
-rewrite(?string, to_existing_atom, [Arg], _) ->
-  {ok, erlang, binary_to_existing_atom, [Arg, utf8]};
-rewrite(?tuple, insert_at, [Tuple, Index, Term], _) ->
-  {ok, erlang, insert_element, [increment(Index), Tuple, Term]};
-rewrite(?tuple, delete_at, [Tuple, Index], _) ->
-  {ok, erlang, delete_element, [increment(Index), Tuple]};
-rewrite(?tuple, duplicate, [Data, Size], _) ->
-  {ok, erlang, make_tuple, [Size, Data]};
-
-rewrite(Receiver, Name, Args, Arity) ->
-  case inline(Receiver, Name, Arity) of
-    {AR, AN} -> {ok, AR, AN, Args};
-    false    -> false
-  end.
-
-increment(Number) when is_number(Number) ->
-  Number + 1;
-increment(Other) ->
-  {{'.', [], [erlang, '+']}, [], [Other, 1]}.
-
-inline(?atom, to_char_list, 1) -> {erlang, atom_to_list};
-inline(?io, iodata_length, 1) -> {erlang, iolist_size};
-inline(?io, iodata_to_binary, 1) -> {erlang, iolist_to_binary};
-inline(?integer, to_string, 1) -> {erlang, integer_to_binary};
-inline(?integer, to_string, 2) -> {erlang, integer_to_binary};
-inline(?integer, to_char_list, 1) -> {erlang, integer_to_list};
-inline(?integer, to_char_list, 2) -> {erlang, integer_to_list};
-inline(?float, to_string, 1) -> {erlang, float_to_binary};
-inline(?float, to_char_list, 1) -> {erlang, float_to_list};
-inline(?list, to_atom, 1) -> {erlang, list_to_atom};
-inline(?list, to_existing_atom, 1) -> {erlang, list_to_existing_atom};
-inline(?list, to_float, 1) -> {erlang, list_to_float};
-inline(?list, to_integer, 1) -> {erlang, list_to_integer};
-inline(?list, to_integer, 2) -> {erlang, list_to_integer};
-inline(?list, to_tuple, 1) -> {erlang, list_to_tuple};
-
-inline(?kernel, '+', 2) -> {erlang, '+'};
-inline(?kernel, '-', 2) -> {erlang, '-'};
-inline(?kernel, '+', 1) -> {erlang, '+'};
-inline(?kernel, '-', 1) -> {erlang, '-'};
-inline(?kernel, '*', 2) -> {erlang, '*'};
-inline(?kernel, '/', 2) -> {erlang, '/'};
-inline(?kernel, '++', 2) -> {erlang, '++'};
-inline(?kernel, '--', 2) -> {erlang, '--'};
-inline(?kernel, 'not', 1) -> {erlang, 'not'};
-inline(?kernel, '<', 2) -> {erlang, '<'};
-inline(?kernel, '>', 2) -> {erlang, '>'};
-inline(?kernel, '<=', 2) -> {erlang, '=<'};
-inline(?kernel, '>=', 2) -> {erlang, '>='};
-inline(?kernel, '==', 2) -> {erlang, '=='};
-inline(?kernel, '!=', 2) -> {erlang, '/='};
-inline(?kernel, '===', 2) -> {erlang, '=:='};
-inline(?kernel, '!==', 2) -> {erlang, '=/='};
-inline(?kernel, abs, 1) -> {erlang, abs};
-inline(?kernel, apply, 2) -> {erlang, apply};
-inline(?kernel, apply, 3) -> {erlang, apply};
-inline(?kernel, binary_part, 3) -> {erlang, binary_part};
-inline(?kernel, bit_size, 1) -> {erlang, bit_size};
-inline(?kernel, byte_size, 1) -> {erlang, byte_size};
-inline(?kernel, 'div', 2) -> {erlang, 'div'};
-inline(?kernel, exit, 1) -> {erlang, exit};
-inline(?kernel, hd, 1) -> {erlang, hd};
-inline(?kernel, is_atom, 1) -> {erlang, is_atom};
-inline(?kernel, is_binary, 1) -> {erlang, is_binary};
-inline(?kernel, is_bitstring, 1) -> {erlang, is_bitstring};
-inline(?kernel, is_boolean, 1) -> {erlang, is_boolean};
-inline(?kernel, is_float, 1) -> {erlang, is_float};
-inline(?kernel, is_function, 1) -> {erlang, is_function};
-inline(?kernel, is_function, 2) -> {erlang, is_function};
-inline(?kernel, is_integer, 1) -> {erlang, is_integer};
-inline(?kernel, is_list, 1) -> {erlang, is_list};
-inline(?kernel, is_map, 1) -> {erlang, is_map};
-inline(?kernel, is_number, 1) -> {erlang, is_number};
-inline(?kernel, is_pid, 1) -> {erlang, is_pid};
-inline(?kernel, is_port, 1) -> {erlang, is_port};
-inline(?kernel, is_reference, 1) -> {erlang, is_reference};
-inline(?kernel, is_tuple, 1) -> {erlang, is_tuple};
-inline(?kernel, length, 1) -> {erlang, length};
-inline(?kernel, make_ref, 0) -> {erlang, make_ref};
-inline(?kernel, map_size, 1) -> {erlang, map_size};
-inline(?kernel, max, 2) -> {erlang, max};
-inline(?kernel, min, 2) -> {erlang, min};
-inline(?kernel, node, 0) -> {erlang, node};
-inline(?kernel, node, 1) -> {erlang, node};
-inline(?kernel, 'rem', 2) -> {erlang, 'rem'};
-inline(?kernel, round, 1) -> {erlang, round};
-inline(?kernel, self, 0) -> {erlang, self};
-inline(?kernel, send, 2) -> {erlang, send};
-inline(?kernel, spawn, 1) -> {erlang, spawn};
-inline(?kernel, spawn, 3) -> {erlang, spawn};
-inline(?kernel, spawn_link, 1) -> {erlang, spawn_link};
-inline(?kernel, spawn_link, 3) -> {erlang, spawn_link};
-inline(?kernel, spawn_monitor, 1) -> {erlang, spawn_monitor};
-inline(?kernel, spawn_monitor, 3) -> {erlang, spawn_monitor};
-inline(?kernel, throw, 1) -> {erlang, throw};
-inline(?kernel, tl, 1) -> {erlang, tl};
-inline(?kernel, trunc, 1) -> {erlang, trunc};
-inline(?kernel, tuple_size, 1) -> {erlang, tuple_size};
-
-inline(?map, keys, 1) -> {maps, keys};
-inline(?map, merge, 2) -> {maps, merge};
-inline(?map, size, 1) -> {maps, size};
-inline(?map, values, 1) -> {maps, values};
-inline(?map, to_list, 1) -> {maps, to_list};
-
-inline(?node, spawn, 2) -> {erlang, spawn};
-inline(?node, spawn, 3) -> {erlang, spawn_opt};
-inline(?node, spawn, 4) -> {erlang, spawn};
-inline(?node, spawn, 5) -> {erlang, spawn_opt};
-inline(?node, spawn_link, 2) -> {erlang, spawn_link};
-inline(?node, spawn_link, 4) -> {erlang, spawn_link};
-
-inline(?process, exit, 2) -> {erlang, exit};
-inline(?process, spawn, 2) -> {erlang, spawn_opt};
-inline(?process, spawn, 4) -> {erlang, spawn_opt};
-inline(?process, demonitor, 1) -> {erlang, demonitor};
-inline(?process, demonitor, 2) -> {erlang, demonitor};
-inline(?process, link, 1) -> {erlang, link};
-inline(?process, unlink, 1) -> {erlang, unlink};
-
-inline(?string, to_float, 1) -> {erlang, binary_to_float};
-inline(?string, to_integer, 1) -> {erlang, binary_to_integer};
-inline(?string, to_integer, 2) -> {erlang, binary_to_integer};
-inline(?system, stacktrace, 0) -> {erlang, get_stacktrace};
-inline(?tuple, to_list, 1) -> {erlang, tuple_to_list};
-
-inline(_, _, _) -> false.
-
 check_deprecation(Meta, Receiver, Name, Arity, #{file := File}) ->
  case deprecation(Receiver, Name, Arity) of
    false -> ok;
@@ -507,15 +348,5 @@ deprecation_message(Warning, Message) ->
    Message -> Warning ++ ", " ++ Message
  end.

-deprecation('Elixir.Mix.Generator', 'from_file', _) ->
-  "instead pass [from_file: file] to embed_text/2 and embed_template/2 macros. "
-  "Note that [from_file: file] expects paths relative to the current working "
-  "directory and not to the current file";
-deprecation('Elixir.EEx.TransformerEngine', '__using__', _) ->
-  "check EEx.SmartEngine for how to build custom engines";
-deprecation('Elixir.EEx.AssignsEngine', '__using__', _) ->
-  "check EEx.SmartEngine for how to build custom engines";
-deprecation('Elixir.Kernel', 'xor', _) ->
-  true; %% Remember to remove xor operator from tokenizer
 deprecation(_, _, _) ->
  false.
@@ -2,36 +2,37 @@
 % This is not exposed in the Elixir language.
 -module(elixir_errors).
 -export([compile_error/3, compile_error/4,
-  form_error/4, parse_error/4, warn/2, warn/3,
+  form_error/4, form_warn/4, parse_error/4, warn/2, warn/3,
  handle_file_warning/2, handle_file_warning/3, handle_file_error/2]).
 -include("elixir.hrl").

-type line_or_meta() :: integer() | list().
+-spec warn(non_neg_integer(), binary(), unicode:chardata()) -> ok.

-warn(Warning) ->
-  CompilerPid = get(elixir_compiler_pid),
-  if
-    CompilerPid =/= undefined ->
-      elixir_code_server:cast({register_warning, CompilerPid});
-    true -> false
-  end,
-  io:put_chars(standard_error, Warning).
+warn(Line, File, Warning) when is_integer(Line), is_binary(File) ->
+  warn(file_format(Line, File), Warning).
+
+-spec warn(unicode:chardata(), unicode:chardata()) -> ok.

 warn(Caller, Warning) ->
-  warn([Caller, "warning: ", Warning]).
+  do_warn([Caller, "warning: ", Warning, $\n]).

-warn(Line, File, Warning) when is_integer(Line) ->
-  warn(file_format(Line, File, "warning: " ++ Warning)).
+%% General forms handling.

-%% Raised during expansion/translation/compilation.
-
-spec form_error(line_or_meta(), binary(), module(), any()) -> no_return().
+-spec form_error(list(), binary(), module(), any()) -> no_return().

 form_error(Meta, File, Module, Desc) ->
  compile_error(Meta, File, format_error(Module, Desc)).

-spec compile_error(line_or_meta(), binary(), iolist()) -> no_return().
-spec compile_error(line_or_meta(), binary(), iolist(), list()) -> no_return().
+-spec form_warn(list(), binary(), module(), any()) -> ok.
+
+form_warn(Meta, File, Module, Desc) when is_list(Meta) ->
+  {MetaLine, MetaFile} = meta_location(Meta, File),
+  warn(MetaLine, MetaFile, format_error(Module, Desc)).
+
+%% Compilation error.
+
+-spec compile_error(list(), binary(), unicode:charlist()) -> no_return().
+-spec compile_error(list(), binary(), string(), list()) -> no_return().

 compile_error(Meta, File, Message) when is_list(Message) ->
  raise(Meta, File, 'Elixir.CompileError', elixir_utils:characters_to_binary(Message)).
@@ -39,23 +40,39 @@ compile_error(Meta, File, Message) when is_list(Message) ->
 compile_error(Meta, File, Format, Args) when is_list(Format)  ->
  compile_error(Meta, File, io_lib:format(Format, Args)).

-%% Raised on tokenizing/parsing
+%% Tokenization parsing/errors.

-spec parse_error(line_or_meta(), binary(), binary(), binary()) -> no_return().
+-spec parse_error(non_neg_integer(), binary(), binary(), binary()) -> no_return().

-parse_error(Meta, File, Error, <<>>) ->
+parse_error(Line, File, Error, <<>>) ->
  Message = case Error of
    <<"syntax error before: ">> -> <<"syntax error: expression is incomplete">>;
    _ -> Error
  end,
-  raise(Meta, File, 'Elixir.TokenMissingError', Message);
+  do_raise(Line, File, 'Elixir.TokenMissingError', Message);

 %% Show a nicer message for missing end tokens
-parse_error(Meta, File, <<"syntax error before: ">>, <<"'end'">>) ->
-  raise(Meta, File, 'Elixir.SyntaxError', <<"unexpected token: end">>);
+parse_error(Line, File, <<"syntax error before: ">>, <<"'end'">>) ->
+  do_raise(Line, File, 'Elixir.SyntaxError', <<"unexpected token: end">>);

-%% Binaries are wrapped in [<<...>>], so we need to unwrap them
-parse_error(Meta, File, Error, <<"[", _/binary>> = Full) when is_binary(Error) ->
+%% Produce a human-readable message for errors before a sigil
+parse_error(Line, File, <<"syntax error before: ">>, <<"{sigil,", _Rest/binary>> = Full) ->
+  {ok, Tokens, _} = erl_scan:string(binary_to_list(Full)),
+  {ok, {sigil, _, Sigil, [Content], _}} = erl_parse:parse_term(Tokens ++ [{dot, 1}]),
+  Message = <<"syntax error before: sigil ~", Sigil," with content '", Content/binary, "'">>,
+  do_raise(Line, File, 'Elixir.SyntaxError', Message);
+
+%% Aliases are wrapped in ['']
+parse_error(Line, File, Error, <<"['", Token/binary>>) when is_binary(Error) ->
+  Rest =
+    case binary:split(Token, <<"'">>) of
+      [Part, _] -> Part;
+      _ -> <<>>
+    end,
+  do_raise(Line, File, 'Elixir.SyntaxError', <<Error/binary, Rest/binary>>);
+
+%% Binaries (and interpolation) are wrapped in [<<...>>]
+parse_error(Line, File, Error, <<"[", _/binary>> = Full) when is_binary(Error) ->
  Rest =
    case binary:split(Full, <<"<<">>) of
      [Lead, Token] ->
@@ -66,27 +83,27 @@ parse_error(Meta, File, Error, <<"[", _/binary>> = Full) when is_binary(Error) -
      [_] ->
        <<$">>
    end,
-  raise(Meta, File, 'Elixir.SyntaxError', <<Error/binary, Rest/binary >>);
+  do_raise(Line, File, 'Elixir.SyntaxError', <<Error/binary, Rest/binary >>);

 %% Everything else is fine as is
-parse_error(Meta, File, Error, Token) when is_binary(Error), is_binary(Token) ->
+parse_error(Line, File, Error, Token) when is_binary(Error), is_binary(Token) ->
  Message = <<Error/binary, Token/binary >>,
-  raise(Meta, File, 'Elixir.SyntaxError', Message).
+  do_raise(Line, File, 'Elixir.SyntaxError', Message).

-%% Handle warnings and errors (called during module compilation)
+%% Handle warnings and errors from Erlang land (called during module compilation)

 %% Ignore on bootstrap
-handle_file_warning(true, _File, {_Line, sys_core_fold, nomatch_guard}) -> [];
-handle_file_warning(true, _File, {_Line, sys_core_fold, {nomatch_shadow, _}}) -> [];
+handle_file_warning(true, _File, {_Line, sys_core_fold, nomatch_guard}) -> ok;
+handle_file_warning(true, _File, {_Line, sys_core_fold, {nomatch_shadow, _}}) -> ok;

 %% Ignore always
-handle_file_warning(_, _File, {_Line, sys_core_fold, useless_building}) -> [];
+handle_file_warning(_, _File, {_Line, sys_core_fold, useless_building}) -> ok;

 %% This is an Erlang bug, it considers {tuple, _}.call to always fail
-handle_file_warning(_, _File, {_Line, v3_kernel, bad_call}) -> [];
+handle_file_warning(_, _File, {_Line, v3_kernel, bad_call}) -> ok;

 %% We handle unused local warnings ourselves
-handle_file_warning(_, _File, {_Line, erl_lint, {unused_function, _}}) -> [];
+handle_file_warning(_, _File, {_Line, erl_lint, {unused_function, _}}) -> ok;

 %% Make no_effect clauses pretty
 handle_file_warning(_, File, {Line, sys_core_fold, {no_effect, {erlang, F, A}}}) ->
@@ -116,7 +133,7 @@ handle_file_warning(_, File, {Line,erl_lint,{undefined_behaviour_func,{Fun,Arity

 handle_file_warning(_, File, {Line,erl_lint,{undefined_behaviour,Module}}) ->
  case elixir_compiler:get_opt(internal) of
-    true  -> [];
+    true  -> ok;
    false ->
      Message = io_lib:format("behaviour ~ts undefined", [elixir_aliases:inspect(Module)]),
      warn(Line, File, Message)
@@ -124,17 +141,29 @@ handle_file_warning(_, File, {Line,erl_lint,{undefined_behaviour,Module}}) ->

 %% Ignore unused vars at "weird" lines (<= 0)
 handle_file_warning(_, _File, {Line,erl_lint,{unused_var,_Var}}) when Line =< 0 ->
-  [];
+  ok;

-%% Ignore shadowed vars as we guarantee no conflicts ourselves
+%% Ignore shadowed and exported vars as we guarantee no conflicts ourselves
 handle_file_warning(_, _File, {_Line,erl_lint,{shadowed_var,_Var,_Where}}) ->
-  [];
+  ok;
+
+handle_file_warning(_, _File, {_Line,erl_lint,{exported_var,_Var,_Where}}) ->
+  ok;
+
+%% Rewrite nomatch_guard to be more generic it can happen inside if, unless, etc
+handle_file_warning(_, File, {Line, sys_core_fold, nomatch_guard}) ->
+  warn(Line, File, "this check/guard will always yield the same result");

 %% Properly format other unused vars
 handle_file_warning(_, File, {Line,erl_lint,{unused_var,Var}}) ->
  Message = format_error(erl_lint, {unused_var, format_var(Var)}),
  warn(Line, File, Message);

+%% Handle literal eval failures
+handle_file_warning(_, File, {Line,sys_core_fold,{eval_failure, Error}}) ->
+  #{'__struct__' := Struct} = 'Elixir.Exception':normalize(error, Error),
+  warn(Line, File, ["this expression will fail with ", elixir_aliases:inspect(Struct)]);
+
 %% Default behaviour
 handle_file_warning(_, File, {Line,Module,Desc}) ->
  Message = format_error(Module, Desc),
@@ -152,39 +181,27 @@ handle_file_error(File, {Line,erl_lint,{unsafe_var,Var,{In,_Where}}}) ->
    _ -> In
  end,
  Message = io_lib:format("cannot define variable ~ts inside ~ts", [format_var(Var), Translated]),
-  raise(Line, File, 'Elixir.CompileError', iolist_to_binary(Message));
+  do_raise(Line, File, 'Elixir.CompileError', elixir_utils:characters_to_binary(Message));

 handle_file_error(File, {Line,erl_lint,{spec_fun_undefined,{M,F,A}}}) ->
  Message = io_lib:format("spec for undefined function ~ts.~ts/~B", [elixir_aliases:inspect(M), F, A]),
-  raise(Line, File, 'Elixir.CompileError', iolist_to_binary(Message));
+  do_raise(Line, File, 'Elixir.CompileError', elixir_utils:characters_to_binary(Message));

 handle_file_error(File, {Line,Module,Desc}) ->
-  form_error(Line, File, Module, Desc).
+  Message = format_error(Module, Desc),
+  do_raise(Line, File, 'Elixir.CompileError', elixir_utils:characters_to_binary(Message)).

 %% Helpers

 raise(Meta, File, Kind, Message) when is_list(Meta) ->
-  raise(?line(Meta), File, Kind, Message);
+  {MetaLine, MetaFile} = meta_location(Meta, File),
+  do_raise(MetaLine, MetaFile, Kind, Message).

-raise(none, File, Kind, Message) ->
-  raise(0, File, Kind, Message);
+file_format(0, File) ->
+  io_lib:format("~ts: ", [elixir_utils:relative_to_cwd(File)]);

-raise(Line, File, Kind, Message) when is_integer(Line), is_binary(File) ->
-  %% Populate the stacktrace so we can raise it
-  try
-    throw(ok)
-  catch
-    ok -> ok
-  end,
-  Stacktrace = erlang:get_stacktrace(),
-  Exception = Kind:exception([{description, Message}, {file, File}, {line, Line}]),
-  erlang:raise(error, Exception, tl(Stacktrace)).
-
-file_format(0, File, Message) when is_binary(File) ->
-  io_lib:format("~ts: ~ts~n", [elixir_utils:relative_to_cwd(File), Message]);
-
-file_format(Line, File, Message) when is_binary(File) ->
-  io_lib:format("~ts:~w: ~ts~n", [elixir_utils:relative_to_cwd(File), Line, Message]).
+file_format(Line, File) ->
+  io_lib:format("~ts:~w: ", [elixir_utils:relative_to_cwd(File), Line]).

 format_var(Var) ->
  list_to_atom(lists:takewhile(fun(X) -> X /= $@ end, atom_to_list(Var))).
@@ -215,3 +232,37 @@ translate_comp_op('=<') -> '<=';
 translate_comp_op('=:=') -> '===';
 translate_comp_op('=/=') -> '!==';
 translate_comp_op(Other) -> Other.
+
+meta_location(Meta, File) ->
+  case lists:keyfind(file, 1, Meta) of
+    {file, MetaFile} when is_binary(MetaFile) ->
+      case lists:keyfind(keep, 1, Meta) of
+        {keep, MetaLine} when is_integer(MetaLine) -> ok;
+        _ -> MetaLine = 0
+      end,
+      {MetaLine, MetaFile};
+    _ ->
+      {?line(Meta), File}
+  end.
+
+do_warn(Warning) ->
+  CompilerPid = get(elixir_compiler_pid),
+  if
+    CompilerPid =/= undefined ->
+      elixir_code_server:cast({register_warning, CompilerPid});
+    true -> false
+  end,
+  io:put_chars(standard_error, Warning),
+  ok.
+
+do_raise(none, File, Kind, Message) ->
+  do_raise(0, File, Kind, Message);
+do_raise(Line, File, Kind, Message) when is_integer(Line), is_binary(File), is_binary(Message) ->
+  try
+    throw(ok)
+  catch
+    ok -> ok
+  end,
+  Stacktrace = erlang:get_stacktrace(),
+  Exception = Kind:exception([{description, Message}, {file, File}, {line, Line}]),
+  erlang:raise(error, Exception, tl(Stacktrace)).
@@ -66,6 +66,8 @@ expand({'__aliases__', _, _} = Alias, E) ->
          elixir_lexical:record_remote(Receiver, ?m(E, lexical_tracker)),
          {Receiver, EA};
        false ->
+          elixir_errors:warn(?m(E, line), ?m(E, file), io_lib:format("an alias must expand to an atom "
+            "at compilation time but got ~ts", ['Elixir.Macro':to_string(hd(EAliases))])),
          {{{'.', [], [elixir_aliases, concat]}, [], [EAliases]}, EA}
      end
  end;
@@ -169,7 +171,7 @@ expand({quote, Meta, [KV, Do]}, E) when is_list(Do) ->
      false -> compile_error(Meta, E#elixir_scope.file, "missing do keyword in quote")
    end,

-  ValidOpts = [context, location, line, unquote, bind_quoted],
+  ValidOpts = [context, location, line, file, unquote, bind_quoted],
  {EKV, ET} = expand_opts(Meta, quote, ValidOpts, KV, E),

  Context = case lists:keyfind(context, 1, EKV) of
@@ -185,8 +187,20 @@ expand({quote, Meta, [KV, Do]}, E) when is_list(Do) ->
      end
  end,

-  Keep = lists:keyfind(location, 1, EKV) == {location, keep},
-  Line = proplists:get_value(line, EKV, false),
+  {File, Line} = case lists:keyfind(location, 1, EKV) of
+    {location, keep} ->
+      {elixir_utils:relative_to_cwd(?m(E, file)), false};
+    false ->
+      { case lists:keyfind(file, 1, EKV) of
+          {file, F} -> F;
+          false -> nil
+        end,
+
+        case lists:keyfind(line, 1, EKV) of
+          {line, L} -> L;
+          false -> false
+        end }
+  end,

  {Binding, DefaultUnquote} = case lists:keyfind(bind_quoted, 1, EKV) of
    {bind_quoted, BQ} -> {BQ, false};
@@ -194,11 +208,11 @@ expand({quote, Meta, [KV, Do]}, E) when is_list(Do) ->
  end,

  Unquote = case lists:keyfind(unquote, 1, EKV) of
-    {unquote, Bool} when is_boolean(Bool) -> Bool;
+    {unquote, U} when is_boolean(U) -> U;
    false -> DefaultUnquote
  end,

-  Q = #elixir_quote{line=Line, keep=Keep, unquote=Unquote, context=Context},
+  Q = #elixir_quote{line=Line, file=File, unquote=Unquote, context=Context},

  {Quoted, _Q} = elixir_quote:quote(Exprs, Binding, Q, ET),
  expand(Quoted, ET);
@@ -296,13 +310,8 @@ expand({Name, Meta, Kind} = Var, #{vars := Vars} = E) when is_atom(Name), is_ato
      VarMeta = lists:keyfind(var, 1, Meta),
      if
        VarMeta == {var, true} ->
-          Extra = case Kind of
-            nil -> "";
-            _   -> io_lib:format(" (context ~ts)", [elixir_aliases:inspect(Kind)])
-          end,
-
-          compile_error(Meta, ?m(E, file), "expected var ~ts~ts to expand to an existing "
-                        "variable or be a part of a match", [Name, Extra]);
+          compile_error(Meta, ?m(E, file), "expected var \"~ts\"~ts to expand to an existing variable "
+                        "or be part of a match", [Name, elixir_scope:context_info(Kind)]);
        true ->
          expand({Name, Meta, []}, E)
      end
@@ -347,7 +356,7 @@ expand({_, Meta, Args} = Invalid, E) when is_list(Meta) and is_list(Args) ->

 expand({_, _, _} = Tuple, E) ->
  compile_error([{line,0}], ?m(E, file), "invalid quoted expression: ~ts",
-    ['Elixir.Kernel':inspect(Tuple, [{records,false}])]);
+    ['Elixir.Kernel':inspect(Tuple, [])]);

 %% Literals

@@ -449,8 +458,7 @@ assert_no_ambiguous_op(_Atom, _Meta, _Args, _E) ->
  ok.

 expand_local(Meta, Name, Args, #{local := nil, function := nil} = E) ->
-  {EArgs, EA} = expand_args(Args, E),
-  {{Name, Meta, EArgs}, EA};
+  compile_error(Meta, ?m(E, file), "undefined function ~ts/~B", [Name, length(Args)]);
 expand_local(Meta, Name, Args, #{local := nil, module := Module, function := Function} = E) ->
  elixir_locals:record_local({Name, length(Args)}, Module, Function),
  {EArgs, EA} = expand_args(Args, E),
@@ -466,7 +474,8 @@ expand_remote(Receiver, DotMeta, Right, Meta, Args, E, EL) ->
    true -> ok
  end,
  {EArgs, EA} = expand_args(Args, E),
-  {{{'.', DotMeta, [Receiver, Right]}, Meta, EArgs}, elixir_env:mergev(EL, EA)}.
+  {elixir_rewrite:rewrite(Receiver, DotMeta, Right, Meta, EArgs),
+   elixir_env:mergev(EL, EA)}.

 %% Lexical helpers

@@ -481,8 +490,8 @@ validate_opts(Meta, Kind, Allowed, Opts, E) when is_list(Opts) ->
                  "unsupported option ~ts given to ~s", ['Elixir.Kernel':inspect(Key), Kind])
  end || {Key, _} <- Opts, not lists:member(Key, Allowed)];

-validate_opts(Meta, Kind, _Allowed, _Opts, S) ->
-  compile_error(Meta, S#elixir_scope.file, "invalid options for ~s, expected a keyword list", [Kind]).
+validate_opts(Meta, Kind, _Allowed, _Opts, E) ->
+  compile_error(Meta, ?m(E, file), "invalid options for ~s, expected a keyword list", [Kind]).

 no_alias_opts(KV) when is_list(KV) ->
  case lists:keyfind(as, 1, KV) of
--- a/Show More
+++ b/Show More