Release v1.0.0-rc1

Add tests for sync_threshold
Get rid of Logger timeout config, closes #2724
2014-08-30 13:33:02 -04:00 · 2014-08-29 08:13:53 -04:00 · 2014-08-29 08:01:03 -04:00 · 2014-08-28 14:10:41 -04:00 · 2014-08-28 20:05:56 +02:00 · 2014-08-28 13:00:36 -04:00
290 changed files with 12447 additions and 5144 deletions
@@ -10,5 +10,4 @@
 /lib/elixir/test/ebin
 /rel/elixir
 erl_crash.dump
-.dialyzer_plt
-.dialyzer.base_plt
+.elixir.plt
@@ -7,3 +7,4 @@ notifications:
    - eric.meadows.jonsson@gmail.com
 otp_release:
  - 17.0
+  - 17.1
@@ -1,18 +1,172 @@
 # Changelog

-## v0.14.3-dev
+## 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
-  * [Kernel] `|>`, `<<<`, `>>>` and `^^^` were made left associative in operator table
-  * [Kernel] `<`, `>`, `<=`, `>=` were given higher precedence than comparison ones (`==`, `!=`, etc) in operator table
-
-* Soft deprecations (no warnings emitted)
+  * [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 +182,7 @@

 * 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 +224,7 @@
  * [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

@@ -11,7 +11,7 @@ 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 +32,7 @@ $(1): lib/$(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 +68,10 @@ 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 +86,11 @@ $(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))
@@ -133,6 +134,7 @@ docs: compile ../ex_doc/bin/ex_doc
 	$(call DOCS,Mix,mix,Mix)
 	$(call DOCS,IEx,iex,IEx)
 	$(call DOCS,ExUnit,ex_unit,ExUnit)
+	$(call 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."
@@ -140,7 +142,7 @@ 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
@@ -164,7 +166,7 @@ $(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 +175,26 @@ 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..."
-	$(Q) dialyzer --plt .dialyzer_plt --add_to_plt -r lib/elixir/ebin lib/ex_unit/ebin lib/eex/ebin lib/iex/ebin lib/mix/ebin
+DIALYZER_OPTS = --no_check_plt --fullpath -Werror_handling -Wunmatched_returns -Wrace_conditions -Wunderspecs
+PLT = .elixir.plt
+
+$(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.
@@ -2,30 +2,30 @@

 This document simply outlines the release process:

-1. Remove `-dev` extension from VERSION
+1. Remove all `-dev` extension from versions (see below for all files)

-2. Ensure CHANGELOG is updated and timestamp
+2. Ensure CHANGELOG is updated and add current date

 3. Commit changes above with title "Release vVERSION" and generate new tag

 4. Run `make clean test` to ensure all tests pass from scratch and the CI is green

-5. Push master and tags
+5. Push master and the new tag

 6. Release new docs with `make release_docs`, move docs to `docs/stable`

-7. Release new zip with `make release_zip`, push new zip to GitHub Releases
+7. Release new zip with `make release_zip`, push new zip to GitHub Releases, name it `Precompiled.zip`

-8. Merge master into stable branch and push it
+8. Fast-forward merge master into stable branch with `git merge master --ff` and push it

 9. After release, bump versions, add `-dev` back and commit

-10. `make release_docs` once again and push it to `elixir-lang.org`
+10. `make release_docs` once again and push it to `elixir-lang/docs`

-11. Also update `release` file in `elixir-lang.org`
+11. Add the release to `elixir.csv` file in `elixir-lang/elixir-lang.github.com`

 ## 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
+1.0.0-rc1
@@ -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
@@ -34,10 +34,9 @@ defmodule EEx do
  All functions in this module accepts EEx-related options.
  They are:

-    * `: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.
+    * `: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.
    * `:engine` - the EEx engine to be used for compilation.

  ## Engine
@@ -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

@@ -98,7 +99,10 @@ defmodule EEx.Engine do
  def handle_expr(buffer, "=", expr) do
    quote do
      tmp = unquote(buffer)
-      tmp <> to_string(unquote(expr))
+      tmp <> (case unquote(expr) do
+        bin when is_binary(bin) -> bin
+        oth -> String.Chars.to_string(oth)
+      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.
@@ -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
@@ -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"
@@ -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
@@ -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 +51,23 @@ defmodule Code do
    :code.del_path(to_char_list(Path.expand path))
  end

+  @doc """
+  Re-add paths given to the command line to keep their position
+  on the overall code path.
+
+  Some tools may change the code path by prepending new items but
+  still want the paths given by the user to have higher priority.
+  Calling this function guarantees the paths are re-added on
+  top of the user given ones.
+  """
+  @spec readd_paths() :: :ok
+  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`.

@@ -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.
@@ -32,10 +26,6 @@ defprotocol Collectable do
  `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.
  """

  @type command :: {:cont, term} | :done | :halt
@@ -85,23 +75,13 @@ defimpl Collectable, for: BitString do

  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
    %{}
@@ -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)
@@ -611,9 +619,14 @@ defmodule Enum do

  @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)

@@ -1396,7 +1405,7 @@ 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 +1577,46 @@ 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,
@@ -1749,25 +1798,13 @@ 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
+  @doc false
  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)
+    into(collection, apply(Collectable, :empty, [collection]), transform)
  end

  @doc """
@@ -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
@@ -611,12 +613,17 @@ 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
@@ -770,8 +777,9 @@ 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 +806,7 @@ defmodule ErlangError do
  defp from_stacktrace(_) do
    {nil, nil, nil}
  end
+
+  defp from_self([{module, _, _, _}, {module, _, _, _}|_]), do: true
+  defp from_self(_), do: false
 end
@@ -126,12 +126,12 @@ defmodule File do
  Typical error reasons are:

    * `:eacces`  - missing search or write permissions for the parent
-                   directories of `path`
+       directories of `path`
    * `:eexist`  - there is already a file or directory named `path`
    * `:enoent`  - a component of `path` does not exist
    * `:enospc`  - there is a no space left on the device
    * `:enotdir` - a component of `path` is not a directory;
-                   on some platforms, `:enoent` is returned instead
+       on some platforms, `:enoent` is returned instead
  """
  @spec mkdir(Path.t) :: :ok | {:error, posix}
  def mkdir(path) do
@@ -308,11 +308,15 @@ 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 +552,8 @@ 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 +574,8 @@ 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}
@@ -665,14 +671,20 @@ 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`.
  """
@@ -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.
@@ -99,57 +101,71 @@ defmodule Float do
  @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 +181,15 @@ 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 +1,181 @@
+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
+    {pid, ref, mon_ref} =
+      try do
+        pid = whereis(manager)
+        ref = Process.monitor(pid)
+        {:ok, msg_ref} = :gen.call(pid, self(), {:add_process_handler, self(), true}, :infinity)
+        {pid, msg_ref, ref}
+      catch
+        :exit, reason -> exit({reason, {__MODULE__, :start, [stream]}})
+      end
+
+    {pid, ref, mon_ref}
+  end
+
+  defp whereis(pid) when is_pid(pid), do: pid
+  defp whereis(atom) when is_atom(atom), do: Process.whereis(atom) || exit(:noproc)
+  defp whereis({:global, name}), do: :global.whereis_name(name)
+  defp whereis({:via, module, name}), do: module.whereis_name(name)
+  defp whereis({atom, node}) do
+    case :rpc.call(node, :erlang, :whereis, [atom]) do
+      :undefined -> exit(:noproc)
+      {:badrpc, :nodedown} -> exit({:nodedown, node})
+      pid when is_pid(pid) -> pid
+    end
+  end
+
+  defp next(%{timeout: timeout} = stream, {pid, ref, mon_ref} = acc) do
+    receive do
+      # 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, {GenEvent.Stream, ^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}}
+
+      # 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}
+    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
+    Task.start(fn -> GenEvent.remove_handler(pid, {GenEvent.Stream, ref}, :shutdown) end)
+    stop(stream, {:removed, acc})
+  end
+
+  defp wait_for_handler_removal(pid, ref, mon_ref) do
+    receive do
+      {_from, {^pid, ^ref}, {notify, _event}} when notify in [:ack_notify, :sync_notify] ->
+        send pid, {ref, :done}
+        wait_for_handler_removal(pid, ref, mon_ref)
+      {:gen_event_EXIT, {GenEvent.Stream, ^ref}, reason} when reason in [:normal, :shutdown] ->
+        Process.demonitor(mon_ref, [:flush])
+        :ok
+      {:gen_event_EXIT, {GenEvent.Stream, ^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}} ->
+        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 +185,26 @@ defmodule Inspect.Algebra do
        Inspect.inspect(map, opts)
      rescue
        e ->
-          res = Inspect.Map.inspect(map, opts)
-          raise ArgumentError,
-            "Got #{inspect e.__struct__} with message " <>
-            "\"#{Exception.message(e)}\" while inspecting #{pretty(res, opts.width)}"
+          # 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)
+              formatted = IO.iodata_to_binary(format(res, :infinity))
+              raise ArgumentError,
+                "Got #{inspect e.__struct__} with message " <>
+                "\"#{Exception.message(e)}\" while inspecting #{formatted}"
+            after
+              Process.delete(:inspect_trap)
+            end
+          end
      end
    else
      Inspect.Map.inspect(map, opts)
@@ -201,9 +232,9 @@ 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 +258,8 @@ 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 +283,15 @@ 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 +334,10 @@ 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 +351,8 @@ 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 +364,8 @@ 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 +381,8 @@ 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 +402,8 @@ 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 +412,63 @@ 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)
+  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 +476,45 @@ 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) :: binary
+  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 +526,4 @@ 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
@@ -5,23 +5,35 @@ defmodule Integer do

  import Bitwise

+  @doc false
+  defmacro odd?(n) do
+    quote do: (unquote(n) &&& 1) == 1
+  end
+
  @doc """
  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

+  @doc false
+  defmacro even?(n) do
+    quote do: (unquote(n) &&& 1) == 0
+  end
+
  @doc """
  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

@@ -115,7 +127,7 @@ 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 +144,7 @@ defmodule Integer do
      '3FF'

  """
-  @spec to_char_list(integer, pos_integer) :: list
+  @spec to_char_list(integer, pos_integer) :: 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 +123,14 @@ defmodule IO do
    end
  end

+  defp do_binread_all(mapped_dev, acc) do
+    case :file.read_line(mapped_dev) 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 +156,9 @@ 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 +179,13 @@ 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. Th 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 +198,9 @@ 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 +300,9 @@ 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 +394,11 @@ 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 +406,11 @@ 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
@@ -8,27 +8,29 @@ 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_underline`   - underlined text (underline)
-    * `:width`           - the width to format the text (80)
+    * `:enabled`           - toggles coloring on and off (true)
+    * `: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)

  Values for the color settings are strings with
  comma-separated ANSI values.
  """
  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",
-     width: 80]
+    [enabled:           true,
+     doc_bold:          [:bright],
+     doc_code:          [:cyan, :bright],
+     doc_headings:      [:yellow, :bright],
+     doc_inline_code:   [:cyan],
+     doc_table_heading: [:reverse],
+     doc_title:         [:reverse, :yellow, :bright],
+     doc_underline:     [:underline],
+     width:             80]
  end

  @doc """
@@ -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
@@ -56,52 +59,63 @@ 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)
-    case stripped do
-      <<bullet, ?\s, item :: binary >> when bullet in @bullets ->
-        process_list(item, rest, count, indent, options)
-      _ ->
-        process_text(rest, [line], indent, false, options)
+  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 ->
+          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(rest, [stripped | text], indent, options)
+      end
    end
  end

-  defp strip_spaces(" " <> line, acc) do
-    strip_spaces(line, acc + 1)
-  end
-
-  defp strip_spaces(rest, acc) do
-    {rest, acc}
-  end
-
  ## Headings

  defp write_h1(heading, options) do
@@ -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)
    |> 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
@@ -204,28 +208,124 @@ defmodule IO.ANSI.Docs do
  end

  # Blank line between code blocks
-  defp process_code([ "", "    " <> line | rest ], code, indent, options) do
+  defp process_code(["", "    " <> line | rest], code, indent, options) do
    process_code(rest, [line, "" | code], indent, options)
  end

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

  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(nil, [], [], 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
@@ -270,7 +370,7 @@ defmodule IO.ANSI.Docs do

  defp length_without_escape(rest, count) do
    case String.next_grapheme(rest) do
-      {_, rest}  -> length_without_escape(rest, count + 1)
+      {_, rest} -> length_without_escape(rest, count + 1)
      nil -> count
    end
  end
@@ -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

@@ -363,14 +461,19 @@ 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.

@@ -1372,14 +1414,26 @@ 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 +1450,9 @@ 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 +1471,18 @@ 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 +1509,77 @@ 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 +1590,18 @@ 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 +1611,20 @@ 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 +1633,38 @@ 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) |> List.unzip() |> List.to_tuple()
+      ...> 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 +1684,13 @@ 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 +1717,13 @@ 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 +1749,9 @@ 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 +1766,15 @@ 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 +1795,7 @@ 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))
      )
@@ -1714,7 +1819,7 @@ defmodule Kernel do

  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
@@ -1723,7 +1828,7 @@ 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

@@ -1770,26 +1875,31 @@ defmodule Kernel do
    quote do: List.Chars.to_char_list(unquote(arg))
  end

+  @doc false
+  defmacro nil?(x) do
+    quote do: unquote(x) == nil
+  end
+
  @doc """
  Checks if the given argument is nil or not.
  Allowed in guard clauses.

  ## 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 +2004,7 @@ 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 +2018,7 @@ 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 +2039,14 @@ 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
          [] -> []
@@ -1964,8 +2078,9 @@ 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 +2091,18 @@ 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

@@ -2561,7 +2635,7 @@ 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 +2893,59 @@ 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)
+  defmacro defstruct(fields) do
+    quote bind_quoted: [fields: fields] do
+      fields = :lists.map(fn
+        {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)

-    fields =
-      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}"
-        end, fields)
+      @struct :maps.put(:__struct__, __MODULE__, :maps.from_list(fields))

-        @struct :maps.put(:__struct__, __MODULE__, :maps.from_list(fields))
-
-        case Module.get_attribute(__MODULE__, :derive) do
-          [] ->
-            :ok
-          derive ->
-            Protocol.__derive__(derive, __MODULE__, __ENV__)
-        end
-
-        @spec __struct__() :: t
-        def __struct__() do
-          @struct
-        end
+      case Module.get_attribute(__MODULE__, :derive) do
+        [] -> :ok
+        derive -> Protocol.__derive__(derive, __MODULE__, __ENV__)
      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
+      @spec __struct__() :: %__MODULE__{}
+      def __struct__() do
+        @struct
      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 +3006,7 @@ 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 +3014,7 @@ 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 +3345,7 @@ defmodule Kernel do

  ## Sigils

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

@@ -3318,15 +3354,15 @@ 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 +3371,18 @@ 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 +3391,15 @@ 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 +3408,12 @@ 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 +3447,13 @@ 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 +3462,7 @@ 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 +3473,7 @@ 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 +3493,7 @@ 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 +3505,8 @@ 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
+  defp at_exit(res) do
    hooks = :elixir_code_server.call(:flush_at_exit)
+    res = Enum.reduce(hooks, res, &exec_fun/2)
+    if hooks == [], do: res, else: at_exit(res)
+  end

-    for hook <- hooks do
-      try do
-        hook.(status)
-      catch
-        kind, reason ->
-          print_error(kind, reason, System.stacktrace)
+  defp exec_fun(fun, res) when is_function(fun, 1) and is_tuple(res) do
+    parent = self()
+
+    {pid, ref} =
+      spawn_monitor fn ->
+        try do
+          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 ->
+            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
-    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
@@ -129,13 +139,15 @@ 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 +174,7 @@ 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 +182,11 @@ 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 +363,8 @@ 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, []} ->
@@ -407,8 +419,8 @@ 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
@@ -18,14 +18,16 @@ 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.match(ets, {:"$1", :_, :_}) |> List.flatten
-    else
-      []
-    end
+    ets = :gen_server.call(to_pid(arg), :ets, @timeout)
+    :ets.match(ets, {:"$1", :_, :_}) |> List.flatten
+  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
@@ -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} =
@@ -87,10 +91,10 @@ 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}
        catch
@@ -99,31 +103,31 @@ defmodule Kernel.ParallelCompiler do
        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
+        if callback = Keyword.get(options, :each_file) do
          callback.(file)
        end

@@ -172,11 +176,11 @@ 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

@@ -186,7 +190,7 @@ defmodule Kernel.ParallelCompiler do
      if all_missing?(entries, waiting, queued) do
        collect_failures(queued, length(queued) - 1)
      end
-      exit(1)
+      exit({:shutdown, 1})
    end
  end

@@ -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
@@ -242,14 +242,14 @@ defmodule Kernel.SpecialForms do
  Here, `val` is interpreted as unsigned.

  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:
+  latter meaning it will be resolved at VM load time). Many options
+  can be given by using `-` as separator:

-      <<102 :: [integer, native], rest :: binary>>
+      <<102 :: integer-native, rest :: binary>>

  Or:

-      <<102 :: [unsigned, big, integer], rest :: binary>>
+      <<102 :: unsigned-big-integer, rest :: binary>>

  And so on.

@@ -271,7 +271,7 @@ defmodule Kernel.SpecialForms do

  We can also match by specifying size and unit explicitly:

-      iex> <<102, _rest :: [size(2), unit(8)]>> = "foo"
+      iex> <<102, _rest :: size(2)-unit(8)>> = "foo"
      "foo"

  However, if we expect a size of 32, it won't match:
@@ -286,12 +286,15 @@ defmodule Kernel.SpecialForms do
  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)`
+  Size and unit can also be specified using a syntax shortcut
+  when passing integer values:

-      iex> << 1 :: 3 >> == << 1 :: size(3) >>
-      true
+      << x :: 8 >> == << x :: size(8) >>
+      << x :: 8 * 4 >> == << x :: size(8)-unit(4) >>
+      << x :: _ * 4 >> == << x :: unit(4) >>
+
+  This syntax reflects the fact the effective size is given by
+  multiplying the size by the unit.

  For floats, `size * unit` must result in 32 or 64, corresponding
  to binary32 and binary64, respectively.
@@ -340,28 +343,9 @@ 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 +1093,7 @@ 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 +1155,10 @@ 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 +1308,13 @@ 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 +1488,9 @@ 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]

-      Tuple :: tuple     # a tuple of any size
-             | {}        # empty tuple
+      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

@@ -104,36 +122,38 @@ defmodule Kernel.Typespec do

  ## Built-in types

-      Built-in type         | Defined as
-      :-------------------- | :---------
-      `term`                | `any`
-      `binary`              | `<< _ :: _ * 8 >>`
-      `bitstring`           | `<< _ :: _ * 1 >>`
-      `boolean`             | `false` &#124; `true`
-      `byte`                | `0..255`
-      `char`                | `0..0xffff`
-      `number`              | `integer` &#124; `float`
-      `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`
-      `mfa`                 | `{atom, atom, arity}`
-      `arity`               | `0..255`
-      `node`                | `atom`
-      `timeout`             | `:infinity` &#124; `non_neg_integer`
-      `no_return`           | `none`
-      `fun`                 | `(... -> any)`
+  Built-in type         | Defined as
+  :-------------------- | :---------
+  `term`                | `any`
+  `binary`              | `<< _ :: _ * 8 >>`
+  `bitstring`           | `<< _ :: _ * 1 >>`
+  `boolean`             | `false` \| `true`
+  `byte`                | `0..255`
+  `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` \| `binary`
+  `iolist`              | `maybe_improper_list(byte` \| `binary` \| `iolist, binary` \| `[])`
+  `module`              | `atom` \| `tuple`
+  `mfa`                 | `{atom, atom, arity}`
+  `arity`               | `0..255`
+  `node`                | `atom`
+  `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.

-      Built-in type     | Can be interpreted as
-      :---------------- | :--------------------
-      `non_neg_integer` | `0..`
-      `pos_integer`     | `1..`
-      `neg_integer`     | `..-1`
+  Built-in type     | Can be interpreted as
+  :---------------- | :--------------------
+  `non_neg_integer` | `0..`
+  `pos_integer`     | `1..`
+  `neg_integer`     | `..-1`

  Types defined in other modules are referred to as "remote types", they are
  referenced as `Module.type_name` (ex. `Enum.t` or `String.t`).
@@ -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}
@@ -640,8 +660,20 @@ 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
@@ -690,7 +722,11 @@ 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 +783,9 @@ 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
@@ -792,7 +828,58 @@ defmodule Kernel.Typespec do
  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
@@ -866,11 +953,11 @@ 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
@@ -899,15 +986,19 @@ 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 +1006,10 @@ 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 +1036,7 @@ 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
@@ -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 the `key` does not exist, raises `KeyError`.

-  If there are duplicated entries, they are all removed and only the first one
+  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 the `key` does not exist, inserts the given `initial` value.

-  If there are duplicated entries, they are all removed and only the first one
+  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

@@ -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]])
@@ -323,8 +325,10 @@ defmodule List do
  end

  @doc """
-  Unzips the given list of lists or tuples into separate lists and returns a
-  list of lists.
+  Unzips the given list of tuples into a list of lists.
+
+  The number of unzipped elements is equal to the size
+  of the smallest tuple in the list.

  ## Examples

@@ -566,7 +570,7 @@ 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 +16,7 @@ defmodule Macro do
    :&&, :||, :<>, :++, :--, :\\, :::, :<-, :.., :|>, :=~,
    :<, :>, :->,
    :+, :-, :*, :/, :=, :|, :.,
-    :and, :or, :xor, :when, :in,
+    :and, :or, :when, :in,
    :<<<, :>>>, :|||, :&&&, :^^^, :~~~]

  @doc false
@@ -35,7 +35,7 @@ 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}
@@ -74,7 +74,7 @@ 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 +86,12 @@ 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 +305,40 @@ 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 +346,9 @@ 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 +379,7 @@ 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 +390,14 @@ 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

@@ -525,11 +559,15 @@ defmodule Macro do

  # All other calls
  def to_string({target, _, args} = ast, fun) when is_list(args) do
-    {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)
+    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
@@ -565,6 +603,26 @@ 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)
@@ -838,7 +896,7 @@ 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 +937,7 @@ 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)
@@ -29,7 +29,7 @@ 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 +42,10 @@ 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 +105,9 @@ 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
@@ -530,7 +520,7 @@ defmodule Module do
          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
@@ -766,15 +756,9 @@ 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 +772,9 @@ 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 +788,12 @@ 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 """
@@ -911,7 +869,9 @@ 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 +893,38 @@ 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, :__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 +932,8 @@ 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

@@ -65,16 +65,19 @@ 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
@@ -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
@@ -320,11 +363,6 @@ defmodule Module.LocalsTracker 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
@@ -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}
@@ -325,23 +403,14 @@ 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}
+  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({:negated, option}, value, _switches) do
-    {option, [:invalid], value}
-  end
-
  defp normalize_option({:default, option}, value, switches) do
    {option, List.wrap(switches[option]), value}
  end
@@ -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
-      :unknown
+  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)
-      _           -> unix_pathtype(name)
-    end |> elem(1) |> IO.chardata_to_string
+    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
  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
@@ -339,9 +339,9 @@ 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.
  """
@@ -351,7 +351,7 @@ defmodule Process do
  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.
  """
@@ -85,11 +85,13 @@ 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 +289,7 @@ 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 +428,7 @@ 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.
@@ -449,7 +451,7 @@ defmodule Protocol do
        end
      end

-      @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 +496,19 @@ defmodule Protocol do
      @protocol [fallback_to_any: !!@fallback_to_any, consolidated: false]

      @doc false
-      @spec __protocol__(atom) :: term
-      Kernel.def __protocol__(:name),      do: __MODULE__
+      @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 +519,20 @@ 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 +550,7 @@ 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 +576,14 @@ 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 +595,9 @@ 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)
@@ -592,10 +613,10 @@ defmodule Protocol do

    found =
      for {:spec, expr, caller} <- specs,
-          Kernel.Typespec.spec_to_signature(expr) == signature do
-          Kernel.Typespec.define_spec(:callback, expr, caller)
-          true
-        end
+        Kernel.Typespec.spec_to_signature(expr) == signature do
+        Kernel.Typespec.define_spec(:callback, expr, caller)
+        true
+      end

    found != []
  end
@@ -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 """
@@ -42,18 +56,7 @@ defmodule Record do
    Macro.escape Record.Extractor.extract(name, opts)
  end

-  @doc """
-  Checks if the given `data` is a record of `kind`.
-
-  This is implemented as a macro so it can be used in guard clauses.
-
-  ## Examples
-
-      iex> record = {User, "jose", 27}
-      iex> Record.record?(record, User)
-      true
-
-  """
+  @doc false
  defmacro record?(data, kind) do
    case Macro.Env.in_guard?(__CALLER__) do
      true ->
@@ -70,6 +73,51 @@ defmodule Record do
    end
  end

+  @doc """
+  Checks if the given `data` is a record of `kind`.
+
+  This is implemented as a macro so it can be used in guard clauses.
+
+  ## Examples
+
+      iex> record = {User, "john", 27}
+      iex> Record.is_record(record, User)
+      true
+
+  """
+  defmacro is_record(data, kind) do
+    case Macro.Env.in_guard?(__CALLER__) do
+      true ->
+        quote do
+          is_tuple(unquote(data)) and tuple_size(unquote(data)) > 0
+            and :erlang.element(1, unquote(data)) == unquote(kind)
+        end
+      false ->
+        quote do
+          result = unquote(data)
+          is_tuple(result) and tuple_size(result) > 0
+            and :erlang.element(1, result) == unquote(kind)
+        end
+    end
+  end
+
+  @doc false
+  defmacro record?(data) do
+    case Macro.Env.in_guard?(__CALLER__) do
+      true ->
+        quote do
+          is_tuple(unquote(data)) and tuple_size(unquote(data)) > 0
+            and is_atom(:erlang.element(1, unquote(data)))
+        end
+      false ->
+        quote do
+          result = unquote(data)
+          is_tuple(result) and tuple_size(result) > 0
+            and is_atom(:erlang.element(1, result))
+        end
+    end
+  end
+
  @doc """
  Checks if the given `data` is a record.

@@ -77,15 +125,15 @@ 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 +159,31 @@ 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 +194,7 @@ 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 +212,7 @@ 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 +228,19 @@ 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 +253,15 @@ 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 +349,21 @@ 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
@@ -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: ""
+
+  @opaque 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}}

@@ -318,12 +321,17 @@ 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")
@@ -338,27 +346,61 @@ 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"]

  """

  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
-    else
-      splits
+  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 zero_to_infinity(0), do: :infinity
-  defp zero_to_infinity(n), do: n
+  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
+      <<_::binary-size(offset), part::binary-size(keep), _::binary>> = string
+      [part|do_split([h|t], string, new_offset, counter - 1, trim)]
+    end
+  end

  @doc ~S"""
  Receives a regex, a binary and a replacement, returns a new
@@ -471,12 +513,12 @@ 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
@@ -509,7 +551,7 @@ 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 +601,13 @@ 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 acc     :: any
  @type element :: any
-  @type index :: non_neg_integer
+  @type index   :: non_neg_integer
  @type default :: any
+  @type       t :: %__MODULE__{}

  # Require Stream.Reducers and its callbacks
  require Stream.Reducers, as: R
@@ -160,7 +162,7 @@ defmodule Stream do
  end

  defp do_chunk(acc(h, {buffer, count} = old, t) = acc, n, pad, f1) do
-    if nil?(pad) || count == 0 do
+    if is_nil(pad) || count == 0 do
      {:cont, acc}
    else
      buffer = :lists.reverse(buffer) ++ Enum.take(pad, n - count)
@@ -336,6 +338,25 @@ 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 +448,7 @@ 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

@@ -561,6 +582,22 @@ 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.

@@ -616,12 +653,14 @@ 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 +672,9 @@ 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 +686,31 @@ 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} ->
+      {:halted, [:outer|acc]} ->
        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, [:inner|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 +882,15 @@ 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 +978,15 @@ 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 +996,8 @@ 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)
@@ -965,11 +1017,17 @@ defmodule Stream do
    {:halted, acc}
  end

+  # TODO: We should check this is a two-item tuple once
+  # we remove support for the deprecated nil
+  # TODO: Support non lists once the previous format
+  # is removed
  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 +1035,40 @@ 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))
+      nil ->
+        IO.write :stderr, "warning: returning nil from Stream.resource/3 is deprecated, " <>
+                          "please return {:halt, acc} instead\n#{Exception.format_stacktrace}"
+        do_resource(next_acc, next_fun, {:halt, acc}, fun, after_fun)
+      {v, next_acc} ->
+        IO.write :stderr, "warning: returning {next, acc} from Stream.resource/3 is deprecated, " <>
+                          "please return {[val], acc} instead\n#{Exception.format_stacktrace}"
+        do_list_resource(next_acc, next_fun, {:cont, acc}, fun, after_fun,
+                         &Enumerable.List.reduce([v], &1, fun))
+    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

@@ -1082,3 +1169,12 @@ defimpl Enumerable, for: Stream do
    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
@@ -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
@@ -672,8 +745,8 @@ 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 +772,8 @@ 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 +859,10 @@ 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 +922,8 @@ 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 +1047,13 @@ 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 +1088,29 @@ 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 +1118,14 @@ 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 +1158,51 @@ 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(string, first..last) when first >= 0 and last >= 0 do
-    do_slice(next_grapheme(string), first, last, 0, "")
+  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) 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, "")
+  def slice(string, first..last) when first >= 0 and last >= 0 do
+    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 """
@@ -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
@@ -28,7 +28,7 @@ defmodule Supervisor 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
@@ -268,7 +268,9 @@ 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 +292,9 @@ 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 +310,9 @@ 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 +341,9 @@ 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 +369,9 @@ 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.
@@ -384,6 +394,12 @@ defmodule Supervisor do
        [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
@@ -202,59 +202,32 @@ 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}
  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 +360,121 @@ 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
+    command = String.to_char_list(command)
+
+    command =
+      if Path.type(command) == :absolute do
+        command
+      else
+        :os.find_executable(command) || command
+      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, command}, 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, bool}|t], opts, into) when is_boolean(bool),
+    do: cmd_opts(t, [:stderr_to_stdout|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
@@ -16,7 +16,7 @@ defmodule Task do
  They are implemented by spawning a process that sends a message
  to the caller once the given computation is performed.

-  Besides `async/1` and `await/2`, tasks can also be 
+  Besides `async/1` and `await/2`, tasks can also be
  started as part of supervision trees and dynamically spawned
  in remote nodes. We will explore all three scenarios next.

@@ -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
@@ -7,6 +7,8 @@ defmodule URI do
            fragment: nil, authority: nil,
            userinfo: nil, host: nil, port: nil

+  @type t :: %__MODULE__{}
+
  import Bitwise

  @ports %{
@@ -66,7 +68,7 @@ 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.
@@ -307,7 +309,7 @@ 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 +349,20 @@ 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
@@ -58,14 +58,26 @@ 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]
+  @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 +169,8 @@ 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 +194,8 @@ 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 +324,7 @@ 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)
@@ -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 +28,10 @@ start(_Type, _Args) ->
      error   -> [binary]
    end,

-  io:setopts(standard_io, Opts),
-  io:setopts(standard_error, [{unicode,true}]),
+  ok = io:setopts(standard_io, Opts),
+  %% Must use undocument {unicode, true} to set unicode on standard_error, more
+  %% info: http://erlang.org/pipermail/erlang-bugs/2014-April/004310.html
+  ok = io:setopts(standard_error, [{unicode,true}]),
  case file:native_name_encoding() of
    latin1 ->
      io:format(standard_error,
@@ -48,16 +50,21 @@ stop(_S) ->
 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 +160,19 @@ 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 ->
-      case Size of
-        default -> ok;
-        _ -> elixir_errors:compile_error(Meta, ?m(E, file), "duplicated size definition in bitstring")
+expand_bit_info(Meta, [{size, _, [_]=Args}|T], Size, Types, E) ->
+  case Size of
+    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].
@@ -11,6 +11,7 @@
  loaded=[],
  at_exit=[],
  pool={[],0},
+  paths={[],[]},
  compiler_options=[{docs,true},{debug_info,true},{warnings_as_errors,false}],
  erl_compiler_options=nil
 }).
@@ -27,9 +28,13 @@ 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 use a code:is_loaded/1 check on
+  %% bootstrap instead of using the more expensive
+  %% code:ensure_loaded/1 multiple times.
+  _ = code:ensure_loaded('Elixir.Macro.Env'),
+  _ = code:ensure_loaded('Elixir.Module.LocalsTracker'),
+  _ = code:ensure_loaded('Elixir.Kernel.LexicalTracker'),
  {ok, #elixir_code_server{}}.

 handle_call({acquire, Path}, From, Config) ->
@@ -64,7 +69,8 @@ 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
@@ -83,6 +89,9 @@ handle_call(erl_compiler_options, _From, Config) ->
      {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}.

@@ -115,7 +124,7 @@ 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 ->
@@ -131,6 +140,9 @@ handle_cast({unload_files, Files}, Config) ->
 handle_cast({return_module_name, H}, #elixir_code_server{pool={T,Counter}} = Config) ->
  {noreply, Config#elixir_code_server{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}.

@@ -1,5 +1,5 @@
 -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").

@@ -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

@@ -70,7 +80,7 @@ code_loading_compilation(Forms, Vars, #{line := Line} = E) ->
  %% process when native is set to true
  AllOpts   = elixir_code_server:call(erl_compiler_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
@@ -128,43 +138,52 @@ 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)
    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),
+  {ok, _} = application:ensure_all_started(elixir),
  elixir_code_server:cast({compiler_options, [{docs,false},{internal,true}]}),
  [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 ->
@@ -214,11 +233,11 @@ format_errors([]) ->
 format_errors(Errors) ->
  lists:foreach(fun ({File, Each}) ->
    BinFile = elixir_utils:characters_to_binary(File),
-    lists:foreach(fun (Error) -> elixir_errors:handle_file_error(BinFile, Error) end, Each)
+    lists:foreach(fun(Error) -> elixir_errors:handle_file_error(BinFile, Error) end, Each)
  end, Errors).

 format_warnings(Bootstrap, Warnings) ->
  lists:foreach(fun ({File, Each}) ->
    BinFile = elixir_utils:characters_to_binary(File),
-    lists:foreach(fun (Warning) -> elixir_errors:handle_file_warning(Bootstrap, BinFile, Warning) end, Each)
+    lists:foreach(fun(Warning) -> elixir_errors:handle_file_warning(Bootstrap, BinFile, Warning) end, Each)
  end, Warnings).
@@ -2,7 +2,7 @@
 -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,
+  delete_definition/2, store_definition/6, unwrap_definitions/2,
  store_each/8, format_error/1]).
 -include("elixir.hrl").

@@ -55,7 +55,7 @@ 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 +64,17 @@ 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),
@@ -76,16 +82,17 @@ 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),
@@ -115,31 +122,36 @@ 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) ->
@@ -148,8 +160,8 @@ 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

@@ -179,7 +191,7 @@ 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),
@@ -216,88 +228,121 @@ 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),
+unwrap_definitions(File, Module) ->
+  Table  = table(Module),
  CTable = clauses_table(Module),
  ets:delete(Table, last),
-  unwrap_definition(ets:tab2list(Table), CTable, [], [], [], [], [], [], []).

-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)
-    end,
+unwrap_definition([Fun|T], File, Module, CTable, All, Private) ->
+  {Tuple, Kind, Line, _, Check, Location, {Defaults, _, _}} = Fun,
+  Export = export(Kind, Tuple),

-  {NewFunctions, NewTail} = case NewFun of
+  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,
+
+      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}) ->
  Tuple = {Name, Arity},
+  HasBody = Clauses =/= [],
  case ets:lookup(Table, Tuple) of
-    [{Tuple, StoredKind, StoredLine, StoredFile, StoredCheck, StoredLocation, StoredDefaults}] ->
+    [{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_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 ]),
@@ -307,7 +352,7 @@ store_each(Check, Kind, File, Location, Table, CTable, Defaults, {function, Line

 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) ->
@@ -315,21 +360,29 @@ check_valid_clause(Line, File, Name, Arity, Kind, Table, StoredLine, StoredFile)
    {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'}),
+  Matches = ets:match(Table, {{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 +392,8 @@ 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 +404,20 @@ 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 +452,9 @@ 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]).
@@ -36,7 +36,7 @@ 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)};
@@ -58,8 +58,9 @@ store(Module, Function, GenerateName) ->
 %% Store pending declarations that were not manually made concrete.

 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

@@ -72,4 +73,4 @@ format_error({no_super, Module, {Name, Arity}}) ->
 format_fa({Name, Arity}) ->
  A = atom_to_binary(Name, utf8),
  B = integer_to_binary(Arity),
-  << A/binary, $/, B/binary >>.
+  << A/binary, $/, B/binary >>.
@@ -4,7 +4,7 @@
 -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").
@@ -18,6 +18,7 @@
 -define(list, 'Elixir.List').
 -define(map, 'Elixir.Map').
 -define(node, 'Elixir.Node').
+-define(port, 'Elixir.Port').
 -define(process, 'Elixir.Process').
 -define(string, 'Elixir.String').
 -define(system, 'Elixir.System').
@@ -30,17 +31,20 @@ 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
@@ -87,7 +91,7 @@ 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} ->
@@ -114,12 +118,12 @@ dispatch_require(_Meta, Receiver, Name, Args, _E, Callback) ->

 %% Macros expansion

-expand_import(Meta, {Name, Arity} = Tuple, Args, E, Extra) ->
-  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),
+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),
+  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.
@@ -476,6 +480,17 @@ inline(?process, demonitor, 2) -> {erlang, demonitor};
 inline(?process, link, 1) -> {erlang, link};
 inline(?process, unlink, 1) -> {erlang, unlink};

+inline(?port, open, 2) -> {erlang, open_port};
+inline(?port, call, 3) -> {erlang, port_call};
+inline(?port, close, 1) -> {erlang, port_close};
+inline(?port, command, 2) -> {erlang, port_command};
+inline(?port, command, 3) -> {erlang, port_command};
+inline(?port, connect, 2) -> {erlang, port_connect};
+inline(?port, control, 3) -> {erlang, port_control};
+inline(?port, info, 1) -> {erlang, port_info};
+inline(?port, info, 2) -> {erlang, port_info};
+inline(?port, list, 0) -> {erlang, ports};
+
 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};
@@ -507,15 +522,19 @@ 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('Elixir.Collectable', 'empty', 1) ->
+  true;
+deprecation('Elixir.Enum', 'traverse', 2) ->
+  true;
+deprecation('Elixir.Kernel', 'nil?', 1) ->
+  true;
+deprecation('Elixir.Record', 'record?', 1) ->
+  true;
+deprecation('Elixir.Record', 'record?', 2) ->
+  true;
+deprecation('Elixir.Integer', 'even?', 1) ->
+  true;
+deprecation('Elixir.Integer', 'odd?', 1) ->
+  true;
 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(), iolist()) -> 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(iolist(), iolist()) -> 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(), iolist()) -> no_return().
+-spec compile_error(list(), binary(), iolist(), 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 +40,23 @@ 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) ->
+parse_error(Line, File, Error, <<"[", _/binary>> = Full) when is_binary(Error) ->
  Rest =
    case binary:split(Full, <<"<<">>) of
      [Lead, Token] ->
@@ -66,27 +67,27 @@ 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) ->
-  Message = <<Error / binary, Token / binary >>,
-  raise(Meta, File, 'Elixir.SyntaxError', Message).
+parse_error(Line, File, Error, Token) when is_binary(Error), is_binary(Token) ->
+  Message = <<Error/binary, Token/binary >>,
+  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}}}) ->
@@ -95,7 +96,7 @@ handle_file_warning(_, File, {Line, sys_core_fold, {no_effect, {erlang, F, A}}})
    false ->
      case erl_internal:bif(F, A) of
        false -> {"the call to :erlang.~ts/~B has no effect", [F,A]};
-        true -> {"the call to ~ts/~B has no effect", [F,A]}
+        true ->  {"the call to ~ts/~B has no effect", [F,A]}
      end
  end,
  Message = io_lib:format(Fmt, Args),
@@ -116,7 +117,7 @@ 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)
@@ -124,11 +125,15 @@ 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
 handle_file_warning(_, _File, {_Line,erl_lint,{shadowed_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}}) ->
@@ -152,39 +157,27 @@ 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 +208,37 @@ 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),
@@ -33,11 +33,8 @@ extract(Line, Scope, Interpol, [$\\, $\r, $\n|Rest], Buffer, Output, Last) ->
 extract(Line, Scope, Interpol, [$\n|Rest], Buffer, Output, Last) ->
  extract(Line+1, Scope, Interpol, Rest, [$\n|Buffer], Output, Last);

-extract(Line, Scope, Interpol, [$\\, $#, ${|Rest], Buffer, Output, Last) ->
-  extract(Line, Scope, Interpol, Rest, [${,$#|Buffer], Output, Last);
-
-extract(Line, Scope, Interpol, [$\\,Char|Rest], Buffer, Output, Last) ->
-  extract(Line, Scope, Interpol, Rest, [Char,$\\|Buffer], Output, Last);
+extract(Line, Scope, true, [$\\, $#, ${|Rest], Buffer, Output, Last) ->
+  extract(Line, Scope, true, Rest, [${,$#|Buffer], Output, Last);

 extract(Line, Scope, true, [$#, ${|Rest], Buffer, Output, Last) ->
  Output1 = build_string(Line, Buffer, Output),
@@ -52,6 +49,9 @@ extract(Line, Scope, true, [$#, ${|Rest], Buffer, Output, Last) ->
      {error, {string, Line, "missing interpolation terminator:}", []}}
  end;

+extract(Line, Scope, Interpol, [$\\,Char|Rest], Buffer, Output, Last) ->
+  extract(Line, Scope, Interpol, Rest, [Char,$\\|Buffer], Output, Last);
+
 %% Catch all clause

 extract(Line, Scope, Interpol, [Char|Rest], Buffer, Output, Last) ->
@@ -74,58 +74,51 @@ unescape_chars(String) ->
  unescape_chars(String, fun unescape_map/1).

 unescape_chars(String, Map) ->
-  Octals = Map($0) /= false,
-  Hex    = Map($x) /= false,
-  unescape_chars(String, Map, Octals, Hex, <<>>).
+  unescape_chars(String, Map, Map($x) == true, <<>>).

-unescape_chars(<<$\\,A,B,C,Rest/binary>>, Map, true, Hex, Acc) when ?is_octal(A), A =< $3, ?is_octal(B), ?is_octal(C) ->
-  append_escaped(Rest, Map, [A,B,C], true, Hex, Acc, 8);
+unescape_chars(<<$\\,$x,A,B,Rest/binary>>, Map, true, Acc) when ?is_hex(A), ?is_hex(B) ->
+  append_escaped(Rest, Map, [A,B], true, Acc, 16);

-unescape_chars(<<$\\,A,B,Rest/binary>>, Map, true, Hex, Acc) when ?is_octal(A), ?is_octal(B) ->
-  append_escaped(Rest, Map, [A,B], true, Hex, Acc, 8);
+unescape_chars(<<$\\,$x,A,Rest/binary>>, Map, true, Acc) when ?is_hex(A) ->
+  append_escaped(Rest, Map, [A], true, Acc, 16);

-unescape_chars(<<$\\,A,Rest/binary>>, Map, true, Hex, Acc) when ?is_octal(A) ->
-  append_escaped(Rest, Map, [A], true, Hex, Acc, 8);
+unescape_chars(<<$\\,$x,${,A,$},Rest/binary>>, Map, true, Acc) when ?is_hex(A) ->
+  append_escaped(Rest, Map, [A], true, Acc, 16);

-unescape_chars(<<$\\,P,A,B,Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B) ->
-  append_escaped(Rest, Map, [A,B], Octal, true, Acc, 16);
+unescape_chars(<<$\\,$x,${,A,B,$},Rest/binary>>, Map, true, Acc) when ?is_hex(A), ?is_hex(B) ->
+  append_escaped(Rest, Map, [A,B], true, Acc, 16);

-unescape_chars(<<$\\,P,A,Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A) ->
-  append_escaped(Rest, Map, [A], Octal, true, Acc, 16);
+unescape_chars(<<$\\,$x,${,A,B,C,$},Rest/binary>>, Map, true, Acc) when ?is_hex(A), ?is_hex(B), ?is_hex(C) ->
+  append_escaped(Rest, Map, [A,B,C], true, Acc, 16);

-unescape_chars(<<$\\,P,${,A,$},Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A) ->
-  append_escaped(Rest, Map, [A], Octal, true, Acc, 16);
+unescape_chars(<<$\\,$x,${,A,B,C,D,$},Rest/binary>>, Map, true, Acc) when ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D) ->
+  append_escaped(Rest, Map, [A,B,C,D], true, Acc, 16);

-unescape_chars(<<$\\,P,${,A,B,$},Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B) ->
-  append_escaped(Rest, Map, [A,B], Octal, true, Acc, 16);
+unescape_chars(<<$\\,$x,${,A,B,C,D,E,$},Rest/binary>>, Map, true, Acc) when ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E) ->
+  append_escaped(Rest, Map, [A,B,C,D,E], true, Acc, 16);

-unescape_chars(<<$\\,P,${,A,B,C,$},Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C) ->
-  append_escaped(Rest, Map, [A,B,C], Octal, true, Acc, 16);
+unescape_chars(<<$\\,$x,${,A,B,C,D,E,F,$},Rest/binary>>, Map, true, Acc) when ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E), ?is_hex(F) ->
+  append_escaped(Rest, Map, [A,B,C,D,E,F], true, Acc, 16);

-unescape_chars(<<$\\,P,${,A,B,C,D,$},Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D) ->
-  append_escaped(Rest, Map, [A,B,C,D], Octal, true, Acc, 16);
+unescape_chars(<<$\\,$x,_/binary>>, _Map, true, _Acc) ->
+  Msg = <<"missing hex sequence after \\x">>,
+  error('Elixir.ArgumentError':exception([{message,Msg}]));

-unescape_chars(<<$\\,P,${,A,B,C,D,E,$},Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E) ->
-    append_escaped(Rest, Map, [A,B,C,D,E], Octal, true, Acc, 16);
-
-unescape_chars(<<$\\,P,${,A,B,C,D,E,F,$},Rest/binary>>, Map, Octal, true, Acc) when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E), ?is_hex(F) ->
-  append_escaped(Rest, Map, [A,B,C,D,E,F], Octal, true, Acc, 16);
-
-unescape_chars(<<$\\,Escaped,Rest/binary>>, Map, Octals, Hex, Acc) ->
+unescape_chars(<<$\\,Escaped,Rest/binary>>, Map, Hex, Acc) ->
  case Map(Escaped) of
-    false -> unescape_chars(Rest, Map, Octals, Hex, <<Acc/binary, $\\, Escaped>>);
-    Other -> unescape_chars(Rest, Map, Octals, Hex, <<Acc/binary, Other>>)
+    false -> unescape_chars(Rest, Map, Hex, <<Acc/binary, $\\, Escaped>>);
+    Other -> unescape_chars(Rest, Map, Hex, <<Acc/binary, Other>>)
  end;

-unescape_chars(<<Char, Rest/binary>>, Map, Octals, Hex, Acc) ->
-  unescape_chars(Rest, Map, Octals, Hex, <<Acc/binary, Char>>);
+unescape_chars(<<Char, Rest/binary>>, Map, Hex, Acc) ->
+  unescape_chars(Rest, Map, Hex, <<Acc/binary, Char>>);

-unescape_chars(<<>>, _Map, _Octals, _Hex, Acc) -> Acc.
+unescape_chars(<<>>, _Map, _Hex, Acc) -> Acc.

-append_escaped(Rest, Map, List, Octal, Hex, Acc, Base) ->
+append_escaped(Rest, Map, List, Hex, Acc, Base) ->
  Codepoint = list_to_integer(List, Base),
  try <<Acc/binary, Codepoint/utf8>> of
-    Binary -> unescape_chars(Rest, Map, Octal, Hex, Binary)
+    Binary -> unescape_chars(Rest, Map, Hex, Binary)
  catch
    error:badarg ->
      Msg = <<"invalid or reserved unicode codepoint ", (integer_to_binary(Codepoint))/binary>>,
@@ -134,6 +127,7 @@ append_escaped(Rest, Map, List, Octal, Hex, Acc, Base) ->

 % Unescape Helpers

+unescape_map($0) -> 0;
 unescape_map($a) -> 7;
 unescape_map($b) -> $\b;
 unescape_map($d) -> $\d;
@@ -144,6 +138,7 @@ unescape_map($r) -> $\r;
 unescape_map($s) -> $\s;
 unescape_map($t) -> $\t;
 unescape_map($v) -> $\v;
+unescape_map($x) -> true;
 unescape_map(E)  -> E.

 % Extract Helpers
@@ -1,6 +1,6 @@
 %% Module responsible for tracking lexical information.
 -module(elixir_lexical).
-export([run/2,
+-export([run/3, dest/1,
  record_alias/4, record_alias/2,
  record_import/4, record_import/2,
  record_remote/2, format_error/1
@@ -9,10 +9,10 @@

 -define(tracker, 'Elixir.Kernel.LexicalTracker').

-run(File, Callback) ->
+run(File, Dest, Callback) ->
  case code:is_loaded(?tracker) of
    {file, _} ->
-      Pid = ?tracker:start_link(),
+      {ok, Pid} = ?tracker:start_link(Dest),
      try
        Callback(Pid)
      after
@@ -24,54 +24,44 @@ run(File, Callback) ->
      Callback(nil)
  end.

+dest(nil) -> nil;
+dest(Pid) -> ?tracker:dest(Pid).
+
 %% RECORD

 record_alias(Module, Line, Warn, Ref) ->
-  if_tracker(Ref, fun(Pid) ->
-    ?tracker:add_alias(Pid, Module, Line, Warn),
-    true
-  end).
+  if_tracker(Ref, fun(Pid) -> ?tracker:add_alias(Pid, Module, Line, Warn), ok end).

 record_import(Module, Line, Warn, Ref) ->
-  if_tracker(Ref, fun(Pid) ->
-    ?tracker:add_import(Pid, Module, Line, Warn),
-    true
-  end).
+  if_tracker(Ref, fun(Pid) -> ?tracker:add_import(Pid, Module, Line, Warn), ok end).

 record_alias(Module, Ref) ->
-  if_tracker(Ref, fun(Pid) ->
-    ?tracker:alias_dispatch(Pid, Module),
-    true
-  end).
+  if_tracker(Ref, fun(Pid) -> ?tracker:alias_dispatch(Pid, Module), ok end).

 record_import(Module, Ref) ->
-  if_tracker(Ref, fun(Pid) ->
-    ?tracker:import_dispatch(Pid, Module),
-    true
-  end).
+  if_tracker(Ref, fun(Pid) -> ?tracker:import_dispatch(Pid, Module), ok end).

 record_remote(Module, Ref) ->
-  if_tracker(Ref, fun(Pid) ->
-    ?tracker:remote_dispatch(Pid, Module),
-    true
-  end).
+  if_tracker(Ref, fun(Pid) -> ?tracker:remote_dispatch(Pid, Module), ok end).

 %% HELPERS

-if_tracker(nil, _Callback) -> false;
+if_tracker(nil, _Callback) -> ok;
 if_tracker(Pid, Callback) when is_pid(Pid) -> Callback(Pid).

 %% ERROR HANDLING

 warn_unused_imports(File, Pid) ->
-  [ begin
-      elixir_errors:handle_file_warning(File, {L, ?MODULE, {unused_import, M}})
-    end || {M, L} <- ?tracker:collect_unused_imports(Pid)].
+  [begin
+    elixir_errors:form_warn([{line, L}], File, ?MODULE, {unused_import, M})
+   end || {M, L} <- ?tracker:collect_unused_imports(Pid)],
+  ok.

 warn_unused_aliases(File, Pid) ->
-  [ begin
-      elixir_errors:handle_file_warning(File, {L, ?MODULE, {unused_alias, M}})
-    end || {M, L} <- ?tracker:collect_unused_aliases(Pid)].
+  [begin
+    elixir_errors:form_warn([{line, L}], File, ?MODULE, {unused_alias, M})
+   end || {M, L} <- ?tracker:collect_unused_aliases(Pid)],
+  ok.

 format_error({unused_alias, Module}) ->
  io_lib:format("unused alias ~ts", [elixir_aliases:inspect(Module)]);
@@ -4,7 +4,7 @@
  setup/1, cleanup/1, cache_env/1, get_cached_env/1,
  record_local/2, record_local/3, record_import/4,
  record_definition/3, record_defaults/4,
-  ensure_no_function_conflict/4, warn_unused_local/3, format_error/1
+  ensure_no_import_conflict/4, warn_unused_local/3, format_error/1
 ]).
 -export([macro_for/3, local_for/3, local_for/4]).

@@ -73,53 +73,45 @@ rewrite_clause(Else, _) -> Else.

 setup(Module) ->
  case code:is_loaded(?tracker) of
-    {file, _} -> ets:insert(Module, {?attr, ?tracker:start_link()});
-    false -> ok
+    {file, _} ->
+      {ok, Pid} = ?tracker:start_link(),
+      ets:insert(Module, {?attr, Pid}),
+      ok;
+    false ->
+      ok
  end.

 cleanup(Module) ->
-  if_tracker(Module, fun(Pid) -> unlink(Pid), ?tracker:stop(Pid) end).
+  if_tracker(Module, fun(Pid) -> unlink(Pid), ?tracker:stop(Pid), ok end).

 record_local(Tuple, Module) when is_atom(Module) ->
-  if_tracker(Module, fun(Pid) ->
-    ?tracker:add_local(Pid, Tuple),
-    true
-  end).
+  if_tracker(Module, fun(Pid) -> ?tracker:add_local(Pid, Tuple), ok end).
 record_local(Tuple, _Module, Function)
-  when Function == nil; Function == Tuple -> false;
+  when Function == nil; Function == Tuple -> ok;
 record_local(Tuple, Module, Function) ->
-  if_tracker(Module, fun(Pid) ->
-    ?tracker:add_local(Pid, Function, Tuple),
-    true
-  end).
+  if_tracker(Module, fun(Pid) -> ?tracker:add_local(Pid, Function, Tuple), ok end).

 record_import(_Tuple, Receiver, Module, _Function)
  when Module == nil; Module == Receiver -> false;
 record_import(Tuple, Receiver, Module, Function) ->
-  if_tracker(Module, fun(Pid) ->
-    ?tracker:add_import(Pid, Function, Receiver, Tuple),
-    true
-  end).
+  if_tracker(Module, fun(Pid) -> ?tracker:add_import(Pid, Function, Receiver, Tuple), ok end).

 record_definition(Tuple, Kind, Module) ->
-  if_tracker(Module, fun(Pid) ->
-    ?tracker:add_definition(Pid, Kind, Tuple),
-    true
-  end).
+  if_tracker(Module, fun(Pid) -> ?tracker:add_definition(Pid, Kind, Tuple), ok end).

 record_defaults(_Tuple, _Kind, _Module, 0) ->
-  true;
+  ok;
 record_defaults(Tuple, Kind, Module, Defaults) ->
-  if_tracker(Module, fun(Pid) ->
-    ?tracker:add_defaults(Pid, Kind, Tuple, Defaults),
-    true
-  end).
+  if_tracker(Module, fun(Pid) -> ?tracker:add_defaults(Pid, Kind, Tuple, Defaults), ok end).

 if_tracker(Module, Callback) ->
+  if_tracker(Module, ok, Callback).
+
+if_tracker(Module, Default, Callback) ->
  try ets:lookup_element(Module, ?attr, 2) of
    Pid -> Callback(Pid)
  catch
-    error:badarg -> false
+    error:badarg -> Default
  end.

 %% CACHING
@@ -140,25 +132,29 @@ get_cached_env(Env) -> Env.

 %% ERROR HANDLING

-ensure_no_function_conflict(Meta, File, Module, AllDefined) ->
-  if_tracker(Module, fun(Pid) ->
-    [ begin
-        elixir_errors:form_error(Meta, File, ?MODULE, {function_conflict, Error})
-      end || Error <- ?tracker:collect_imports_conflicts(Pid, AllDefined) ]
-  end),
-  ok.
+ensure_no_import_conflict(_Line, _File, 'Elixir.Kernel', _All) ->
+  ok;
+ensure_no_import_conflict(Line, File, Module, All) ->
+  if_tracker(Module, ok, fun(Pid) ->
+    _ = [ begin
+        elixir_errors:form_error([{line, Line}], File, ?MODULE, {function_conflict, Error})
+      end || Error <- ?tracker:collect_imports_conflicts(Pid, All) ],
+    ok
+  end).

 warn_unused_local(File, Module, Private) ->
-  if_tracker(Module, fun(Pid) ->
-    Args = [ {Fun, Kind, Defaults} ||
-             {Fun, Kind, _Line, true, Defaults} <- Private],
+  if_tracker(Module, [], fun(Pid) ->
+    Args = [{Fun, Kind, Defaults} ||
+            {Fun, Kind, _Line, true, Defaults} <- Private],

-    Unused = ?tracker:collect_unused_locals(Pid, Args),
+    {Unreachable, Warnings} = ?tracker:collect_unused_locals(Pid, Args),

-    [ begin
-        {_, _, Line, _, _} = lists:keyfind(element(2, Error), 1, Private),
-        elixir_errors:handle_file_warning(File, {Line, ?MODULE, Error})
-      end || Error <- Unused ]
+    [begin
+      {_, _, Line, _, _} = lists:keyfind(element(2, Error), 1, Private),
+      elixir_errors:form_warn([{line, Line}], File, ?MODULE, Error)
+     end || Error <- Warnings ],
+
+    Unreachable
  end).

 format_error({function_conflict,{Receivers, Name, Arity}}) ->
@@ -22,19 +22,8 @@ expand_struct(Meta, Left, Right, E) ->

  EMeta =
    case lists:member(ELeft, ?m(E, context_modules)) of
-      true ->
-        case (ELeft == ?m(E, module)) and
-             (?m(E, function) == nil) of
-          true ->
-            compile_error(Meta, ?m(E, file),
-              "cannot access struct ~ts in body of the module that defines it as "
-              "the struct fields are not yet accessible",
-              [elixir_aliases:inspect(ELeft)]);
-          false ->
-            [{struct, context}|Meta]
-        end;
-      false ->
-        Meta
+      true  -> [{struct, context}|Meta];
+      false -> Meta
    end,

  case ERight of
@@ -90,12 +79,11 @@ translate_struct(Meta, Name, {'%{}', MapMeta, Args}, S) ->
 %% Helpers

 load_struct(Meta, Name, S) ->
+  Context = lists:keyfind(struct, 1, Meta) == {struct, context},
+
  Local =
-    elixir_module:is_open(Name) andalso
-    (case lists:keyfind(struct, 1, Meta) of
-      {struct, context} -> true;
-      _ -> wait_for_struct(Name)
-    end),
+    not(ensure_loaded(Name)) andalso
+      (Context orelse wait_for_struct(Name)),

  try
    case Local of
@@ -112,8 +100,22 @@ load_struct(Meta, Name, S) ->
  catch
    error:undef ->
      Inspected = elixir_aliases:inspect(Name),
-      compile_error(Meta, S#elixir_scope.file, "~ts.__struct__/0 is undefined, "
-        "cannot expand struct ~ts", [Inspected, Inspected])
+
+      case Context andalso (S#elixir_scope.function == nil) of
+        true ->
+          compile_error(Meta, S#elixir_scope.file,
+            "cannot access struct ~ts, the struct was not yet defined or the struct is being "
+            "accessed in the same context that defines it", [Inspected]);
+        false ->
+          compile_error(Meta, S#elixir_scope.file, "~ts.__struct__/0 is undefined, "
+            "cannot expand struct ~ts", [Inspected, Inspected])
+      end
+  end.
+
+ensure_loaded(Module) ->
+  case code:ensure_loaded(Module) of
+    {module, Module} -> true;
+    {error, _} -> false
  end.

 wait_for_struct(Module) ->
@@ -34,7 +34,7 @@ compile(Module, Block, Vars, #{line := Line} = Env) when is_atom(Module) ->

  case ?m(LexEnv, lexical_tracker) of
    nil ->
-      elixir_lexical:run(?m(LexEnv, file), fun(Pid) ->
+      elixir_lexical:run(?m(LexEnv, file), nil, fun(Pid) ->
        do_compile(Line, Module, Block, Vars, LexEnv#{lexical_tracker := Pid})
      end);
    _ ->
@@ -42,35 +42,41 @@ compile(Module, Block, Vars, #{line := Line} = Env) when is_atom(Module) ->
  end;

 compile(Module, _Block, _Vars, #{line := Line, file := File}) ->
-  elixir_errors:form_error(Line, File, ?MODULE, {invalid_module, Module}).
+  elixir_errors:form_error([{line, Line}], File, ?MODULE, {invalid_module, Module}).

 do_compile(Line, Module, Block, Vars, E) ->
  File = ?m(E, file),
  check_module_availability(Line, File, Module),
-  build(Line, File, Module, ?m(E, lexical_tracker)),
+
+  Docs = elixir_compiler:get_opt(docs),
+  build(Line, File, Module, Docs, ?m(E, lexical_tracker)),

  try
    {Result, NE} = eval_form(Line, Module, Block, Vars, E),
-    {Base, Export, Private, Def, Defmacro, Functions} = elixir_def:unwrap_definitions(Module),

-    {All, Forms0} = functions_form(Line, File, Module, Base, Export, Def, Defmacro, Functions),
-    Forms1        = specs_form(Module, Private, Defmacro, Forms0),
-    Forms2        = types_form(Module, Forms1),
-    Forms3        = attributes_form(Line, File, Module, Forms2),
-
-    case ets:lookup(data_table(Module), 'on_load') of
+    _ = case ets:lookup(data_table(Module), 'on_load') of
      [] -> ok;
      [{on_load,OnLoad}] ->
        [elixir_locals:record_local(Tuple, Module) || Tuple <- OnLoad]
    end,

-    AllFunctions = Def ++ [T || {T, defp, _, _, _} <- Private],
-    elixir_locals:ensure_no_function_conflict(Line, File, Module, AllFunctions),
-    elixir_locals:warn_unused_local(File, Module, Private),
-    warn_invalid_clauses(Line, File, Module, All),
-    warn_unused_docs(Line, File, Module),
+    {Def, Defp, Defmacro, Defmacrop, Exports, Functions} =
+      elixir_def:unwrap_definitions(File, Module),

-    Location = {elixir_utils:relative_to_cwd(elixir_utils:characters_to_list(File)), Line},
+    {All, Forms0} = functions_form(Line, File, Module, Def, Defp,
+                                   Defmacro, Defmacrop, Exports, Functions),
+    Forms1        = specs_form(Module, Defmacro, Defmacrop, Forms0),
+    Forms2        = types_form(Line, File, Module, Forms1),
+    Forms3        = attributes_form(Line, File, Module, Forms2),
+
+    elixir_locals:ensure_no_import_conflict(Line, File, Module, All),
+
+    case Docs of
+      true  -> warn_unused_docs(Line, File, Module, doc);
+      false -> false
+    end,
+
+    Location = {elixir_utils:characters_to_list(elixir_utils:relative_to_cwd(File)), Line},

    Final = [
      {attribute, Line, file, Location},
@@ -88,7 +94,7 @@ do_compile(Line, Module, Block, Vars, E) ->

 %% Hook that builds both attribute and functions and set up common hooks.

-build(Line, File, Module, Lexical) ->
+build(Line, File, Module, Docs, Lexical) ->
  %% Table with meta information about the module.
  DataTable = data_table(Module),

@@ -97,16 +103,16 @@ build(Line, File, Module, Lexical) ->
    true ->
      [{OldFile, OldLine}] = ets:lookup_element(OldTable, ?location_attr, 2),
      Error = {module_in_definition, Module, OldFile, OldLine},
-      elixir_errors:form_error(Line, File, ?MODULE, Error);
+      elixir_errors:form_error([{line, Line}], File, ?MODULE, Error);
    false ->
      []
  end,

-  ets:new(DataTable, [set, named_table, public]),
+  DataTable = ets:new(DataTable, [set, named_table, public]),
  ets:insert(DataTable, {before_compile, []}),
  ets:insert(DataTable, {after_compile, []}),

-  case elixir_compiler:get_opt(docs) of
+  case Docs of
    true -> ets:insert(DataTable, {on_definition, [{'Elixir.Module', compile_doc}]});
    _    -> ets:insert(DataTable, {on_definition, []})
  end,
@@ -121,7 +127,8 @@ build(Line, File, Module, Lexical) ->

  %% Setup other modules
  elixir_def:setup(Module),
-  elixir_locals:setup(Module).
+  elixir_locals:setup(Module),
+  ok.

 %% Receives the module representation and evaluates it.

@@ -143,16 +150,13 @@ eval_callbacks(Line, Module, Name, Args, E) ->

 %% Return the form with exports and function declarations.

-functions_form(Line, File, Module, BaseAll, BaseExport, Def, Defmacro, BaseFunctions) ->
-  {InfoSpec, Info} = add_info_function(Line, File, Module, BaseExport, Def, Defmacro),
+functions_form(Line, File, Module, Def, Defp, Defmacro, Defmacrop, Exports, Body) ->
+  All = Def ++ Defmacro ++ Defp ++ Defmacrop,
+  {Spec, Info} = add_info_function(Line, File, Module, All, Def, Defmacro),

-  All       = [{'__info__', 1}|BaseAll],
-  Export    = [{'__info__', 1}|BaseExport],
-  Functions = [InfoSpec,Info|BaseFunctions],
-
-  {All, [
-    {attribute, Line, export, lists:sort(Export)} | Functions
-  ]}.
+  {[{'__info__',1}|All],
+   [{attribute, Line, export, lists:sort([{'__info__',1}|Exports])},
+    Spec, Info | Body]}.

 %% Add attributes handling to the form

@@ -188,12 +192,12 @@ process_attribute(_Line, _File, _Key, Values) ->
 process_external_resource(_Line, _File, Value) when is_binary(Value) ->
  Value;
 process_external_resource(Line, File, Value) ->
-  elixir_errors:handle_file_error(File,
-    {Line, ?MODULE, {invalid_external_resource, Value}}).
+  elixir_errors:form_error([{line, Line}], File,
+    ?MODULE, {invalid_external_resource, Value}).

 %% Types

-types_form(Module, Forms0) ->
+types_form(Line, File, Module, Forms0) ->
  case code:ensure_loaded('Elixir.Kernel.Typespec') of
    {module, 'Elixir.Kernel.Typespec'} ->
      Types0 = 'Elixir.Module':get_attribute(Module, type) ++
@@ -207,6 +211,8 @@ types_form(Module, Forms0) ->
      'Elixir.Module':delete_attribute(Module, typep),
      'Elixir.Module':delete_attribute(Module, opaque),

+      warn_unused_docs(Line, File, Module, typedoc),
+
      Forms1 = types_attributes(Types1, Forms0),
      Forms2 = export_types_attributes(Types1, Forms1),
      typedocs_attributes(Types1, Forms2);
@@ -241,11 +247,9 @@ typedocs_attributes(Types, Forms) ->

 %% Specs

-specs_form(Module, Private, Defmacro, Forms) ->
+specs_form(Module, Defmacro, Defmacrop, Forms) ->
  case code:ensure_loaded('Elixir.Kernel.Typespec') of
    {module, 'Elixir.Kernel.Typespec'} ->
-      Defmacrop = [Tuple || {Tuple, defmacrop, _, _, _} <- Private],
-
      Specs0 = 'Elixir.Module':get_attribute(Module, spec) ++
               'Elixir.Module':get_attribute(Module, callback),

@@ -274,10 +278,10 @@ specs_attributes(Forms, Specs) ->
  end, Forms, Dict).

 translate_macro_spec({{spec, NameArity, Spec}, Line}, Defmacro, Defmacrop) ->
-  case ordsets:is_element(NameArity, Defmacrop) of
+  case lists:member(NameArity, Defmacrop) of
    true  -> [];
    false ->
-      case ordsets:is_element(NameArity, Defmacro) of
+      case lists:member(NameArity, Defmacro) of
        true ->
          {Name, Arity} = NameArity,
          [{{spec, {elixir_utils:macro_name(Name), Arity + 1}, spec_for_macro(Spec)}, Line}];
@@ -303,8 +307,8 @@ compile_opts(Module) ->
    [] -> []
  end.

-load_form(Line, Forms, Opts, #{file := File} = E) ->
-  elixir_compiler:module(Forms, File, Opts, fun(Module, Binary0) ->
+load_form(Line, Forms, Opts, E) ->
+  elixir_compiler:module(Forms, Opts, E, fun(Module, Binary0) ->
    Docs = elixir_compiler:get_opt(docs),
    Binary = add_docs_chunk(Binary0, Module, Line, Docs),
    eval_callbacks(Line, Module, after_compile, [E, Binary], E),
@@ -314,14 +318,14 @@ load_form(Line, Forms, Opts, #{file := File} = E) ->
        put(elixir_compiled, [{Module,Binary}|Current]),

        case get(elixir_compiler_pid) of
-          undefined -> [];
+          undefined -> ok;
          PID ->
            Ref = make_ref(),
-            PID ! {module_available, self(), Ref, File, Module, Binary},
+            PID ! {module_available, self(), Ref, ?m(E, file), Module, Binary},
            receive {Ref, ack} -> ok end
        end;
      _ ->
-        []
+        ok
    end,

    Binary
@@ -345,13 +349,12 @@ get_docs(Module) ->
 get_moduledoc(Line, Module) ->
  {Line, 'Elixir.Module':get_attribute(Module, moduledoc)}.

-
 check_module_availability(Line, File, Module) ->
  Reserved = ['Elixir.Any', 'Elixir.BitString', 'Elixir.Function', 'Elixir.PID',
              'Elixir.Reference', 'Elixir.Elixir', 'Elixir'],

  case lists:member(Module, Reserved) of
-    true  -> elixir_errors:handle_file_error(File, {Line, ?MODULE, {module_reserved, Module}});
+    true  -> elixir_errors:form_error([{line, Line}], File, ?MODULE, {module_reserved, Module});
    false -> ok
  end,

@@ -359,7 +362,7 @@ check_module_availability(Line, File, Module) ->
    false ->
      case code:ensure_loaded(Module) of
        {module, _} ->
-          elixir_errors:handle_file_warning(File, {Line, ?MODULE, {module_defined, Module}});
+          elixir_errors:form_warn([{line, Line}], File, ?MODULE, {module_defined, Module});
        {error, _}  ->
          ok
      end;
@@ -367,56 +370,64 @@ check_module_availability(Line, File, Module) ->
      ok
  end.

-warn_invalid_clauses(_Line, _File, 'Elixir.Kernel.SpecialForms', _All) -> ok;
-warn_invalid_clauses(_Line, File, Module, All) ->
-  ets:foldl(fun
-    ({_, _, Kind, _, _}, _) when Kind == type; Kind == opaque ->
-      ok;
-    ({Tuple, Line, _, _, _}, _) ->
-      case lists:member(Tuple, All) of
-        false ->
-          elixir_errors:handle_file_warning(File, {Line, ?MODULE, {invalid_clause, Tuple}});
-        true ->
-          ok
-      end
-  end, ok, docs_table(Module)).
+warn_unused_docs(Line, File, Module, Attribute) ->
+  case ets:member(data_table(Module), Attribute) of
+    true ->
+      elixir_errors:form_warn([{line, Line}], File, ?MODULE, {unused_doc, Attribute});
+    _ ->
+      ok
+  end.

-warn_unused_docs(Line, File, Module) ->
-  lists:foreach(fun(Attribute) ->
-    case ets:member(data_table(Module), Attribute) of
-      true ->
-        elixir_errors:handle_file_warning(File, {Line, ?MODULE, {unused_doc, Attribute}});
-      _ ->
-        ok
-    end
-  end, [typedoc]).
+% __INFO__

-% EXTRA FUNCTIONS
-
-add_info_function(Line, File, Module, Export, Def, Defmacro) ->
+add_info_function(Line, File, Module, All, Def, Defmacro) ->
  Pair = {'__info__', 1},
-  case lists:member(Pair, Export) of
+  case lists:member(Pair, All) of
    true  ->
-      elixir_errors:form_error(Line, File, ?MODULE, {internal_function_overridden, Pair});
+      elixir_errors:form_error([{line, Line}], File, ?MODULE, {internal_function_overridden, Pair});
    false ->
-      {
-        {attribute, Line, spec, {{'__info__', 1},
-          [{type, Line, 'fun', [{type, Line, product, [ {type, Line, atom, []}]}, {type, Line, term, []} ]}]
+      Spec =
+        {attribute, Line, spec, {Pair,
+          [{type, Line, 'fun', [
+            {type, Line, product, [
+              {type, Line, union, [
+                {atom, Line, attributes},
+                {atom, Line, compile},
+                {atom, Line, exports},
+                {atom, Line, functions},
+                {atom, Line, imports},
+                {atom, Line, macros},
+                {atom, Line, module}
+              ]}
+            ]},
+            {type, Line, union, [
+              {type, Line, atom, []},
+              {type, Line, list, [
+                {type, Line, tuple, [
+                  {type, Line, atom, []},
+                  {type, Line, any, []}
+                ]}
+              ]}
+            ]}
+          ]}]
        }},
+
+      Info =
        {function, 0, '__info__', 1, [
          functions_clause(Def),
          macros_clause(Defmacro),
          module_clause(Module),
          else_clause()
-        ]}
-      }
+        ]},
+
+      {Spec, Info}
  end.

 functions_clause(Def) ->
-  {clause, 0, [{atom, 0, functions}], [], [elixir_utils:elixir_to_erl(Def)]}.
+  {clause, 0, [{atom, 0, functions}], [], [elixir_utils:elixir_to_erl(lists:sort(Def))]}.

 macros_clause(Defmacro) ->
-  {clause, 0, [{atom, 0, macros}], [], [elixir_utils:elixir_to_erl(Defmacro)]}.
+  {clause, 0, [{atom, 0, macros}], [], [elixir_utils:elixir_to_erl(lists:sort(Defmacro))]}.

 module_clause(Module) ->
  {clause, 0, [{atom, 0, module}], [], [{atom, 0, Module}]}.
@@ -476,8 +487,6 @@ prune_stacktrace(Info, []) ->

 % ERROR HANDLING

-format_error({invalid_clause, {Name, Arity}}) ->
-  io_lib:format("empty clause provided for nonexistent function or macro ~ts/~B", [Name, Arity]);
 format_error({invalid_external_resource, Value}) ->
  io_lib:format("expected a string value for @external_resource, got: ~p",
    ['Elixir.Kernel':inspect(Value)]);
@@ -7,7 +7,7 @@ Nonterminals
  add_op_eol mult_op_eol hat_op_eol two_op_eol pipe_op_eol stab_op_eol
  arrow_op_eol match_op_eol when_op_eol in_op_eol in_match_op_eol
  type_op_eol rel_op_eol
-  open_paren close_paren empty_paren
+  open_paren close_paren empty_paren eoe
  list list_args open_bracket close_bracket
  tuple open_curly close_curly
  bit_string open_bit close_bit
@@ -16,11 +16,11 @@ Nonterminals
  container_args_base container_args call_args_parens_base call_args_parens parens_call
  call_args_no_parens_one call_args_no_parens_expr call_args_no_parens_comma_expr
  call_args_no_parens_all call_args_no_parens_many call_args_no_parens_many_strict
-  stab stab_eol stab_expr stab_maybe_expr stab_parens_many
+  stab stab_eoe stab_expr stab_maybe_expr stab_parens_many
  kw_eol kw_base kw call_args_no_parens_kw_expr call_args_no_parens_kw
  dot_op dot_alias dot_identifier dot_op_identifier dot_do_identifier
  dot_paren_identifier dot_bracket_identifier
-  do_block fn_eol do_eol end_eol block_eol block_item block_list
+  do_block fn_eoe do_eoe end_eoe block_eoe block_item block_list
  .

 Terminals
@@ -32,13 +32,13 @@ Terminals
  comp_op at_op unary_op and_op or_op arrow_op match_op in_op in_match_op
  type_op dual_op add_op mult_op hat_op two_op pipe_op stab_op when_op assoc_op
  capture_op rel_op
-  'true' 'false' 'nil' 'do' eol ',' '.'
+  'true' 'false' 'nil' 'do' eol ';' ',' '.'
  '(' ')' '[' ']' '{' '}' '<<' '>>' '%{}' '%'
  .

 Rootsymbol grammar.

-%% There are two shift/reduce conflicts coming from call_args_parens.
+%% Two shift/reduce conflicts coming from call_args_parens.
 Expect 2.

 %% Changes in ops and precedence should be reflected on lib/elixir/lib/macro.ex
@@ -54,7 +54,7 @@ Right     60 type_op_eol.     %% ::
 Right     70 pipe_op_eol.     %% |
 Right     80 assoc_op_eol.    %% =>
 Right     90 match_op_eol.    %% =
-Left     130 or_op_eol.       %% ||, |||, or, xor
+Left     130 or_op_eol.       %% ||, |||, or
 Left     140 and_op_eol.      %% &&, &&&, and
 Left     150 comp_op_eol.     %% ==, !=, =~, ===, !==
 Left     160 rel_op_eol.      %% <, >, <=, >=
@@ -72,16 +72,16 @@ Nonassoc 330 dot_identifier.

 %%% MAIN FLOW OF EXPRESSIONS

-grammar -> eol : nil.
+grammar -> eoe : nil.
 grammar -> expr_list : to_block('$1').
-grammar -> eol expr_list : to_block('$2').
-grammar -> expr_list eol : to_block('$1').
-grammar -> eol expr_list eol : to_block('$2').
+grammar -> eoe expr_list : to_block('$2').
+grammar -> expr_list eoe : to_block('$1').
+grammar -> eoe expr_list eoe : to_block('$2').
 grammar -> '$empty' : nil.

 % Note expressions are on reverse order
 expr_list -> expr : ['$1'].
-expr_list -> expr_list eol expr : ['$3'|'$1'].
+expr_list -> expr_list eoe expr : ['$3'|'$1'].

 expr -> empty_paren : nil.
 expr -> matched_expr : '$1'.
@@ -202,8 +202,12 @@ access_expr -> bracket_expr : '$1'.
 access_expr -> at_op_eol number : build_unary_op('$1', ?exprs('$2')).
 access_expr -> unary_op_eol number : build_unary_op('$1', ?exprs('$2')).
 access_expr -> capture_op_eol number : build_unary_op('$1', ?exprs('$2')).
-access_expr -> fn_eol stab end_eol : build_fn('$1', build_stab(reverse('$2'))).
+access_expr -> fn_eoe stab end_eoe : build_fn('$1', build_stab(reverse('$2'))).
 access_expr -> open_paren stab close_paren : build_stab(reverse('$2')).
+access_expr -> open_paren stab ';' close_paren : build_stab(reverse('$2')).
+access_expr -> open_paren ';' stab ';' close_paren : build_stab(reverse('$3')).
+access_expr -> open_paren ';' stab close_paren : build_stab(reverse('$3')).
+access_expr -> open_paren ';' close_paren : build_stab([]).
 access_expr -> number : ?exprs('$1').
 access_expr -> signed_number : {element(4, '$1'), meta('$1'), ?exprs('$1')}.
 access_expr -> list : element(1, '$1').
@@ -226,7 +230,6 @@ max_expr -> parens_call call_args_parens : build_identifier('$1', '$2').
 max_expr -> parens_call call_args_parens call_args_parens : build_nested_parens('$1', '$2', '$3').
 max_expr -> dot_alias : '$1'.

-bracket_arg -> open_bracket ']' : build_list('$1', []).
 bracket_arg -> open_bracket kw close_bracket : build_list('$1', '$2').
 bracket_arg -> open_bracket container_expr close_bracket : build_list('$1', '$2').
 bracket_arg -> open_bracket container_expr ',' close_bracket : build_list('$1', '$2').
@@ -241,28 +244,32 @@ bracket_at_expr -> at_op_eol access_expr bracket_arg :

 %% Blocks

-do_block -> do_eol 'end' : [[{do,nil}]].
-do_block -> do_eol stab end_eol : [[{do, build_stab(reverse('$2'))}]].
-do_block -> do_eol block_list 'end' : [[{do, nil}|'$2']].
-do_block -> do_eol stab_eol block_list 'end' : [[{do, build_stab(reverse('$2'))}|'$3']].
+do_block -> do_eoe 'end' : [[{do,nil}]].
+do_block -> do_eoe stab end_eoe : [[{do, build_stab(reverse('$2'))}]].
+do_block -> do_eoe block_list 'end' : [[{do, nil}|'$2']].
+do_block -> do_eoe stab_eoe block_list 'end' : [[{do, build_stab(reverse('$2'))}|'$3']].

-fn_eol -> 'fn' : '$1'.
-fn_eol -> 'fn' eol : '$1'.
+eoe -> eol : '$1'.
+eoe -> ';' : '$1'.
+eoe -> eol ';' : '$1'.

-do_eol -> 'do' : '$1'.
-do_eol -> 'do' eol : '$1'.
+fn_eoe -> 'fn' : '$1'.
+fn_eoe -> 'fn' eoe : '$1'.

-end_eol -> 'end' : '$1'.
-end_eol -> eol 'end' : '$2'.
+do_eoe -> 'do' : '$1'.
+do_eoe -> 'do' eoe : '$1'.

-block_eol -> block_identifier : '$1'.
-block_eol -> block_identifier eol : '$1'.
+end_eoe -> 'end' : '$1'.
+end_eoe -> eoe 'end' : '$2'.
+
+block_eoe -> block_identifier : '$1'.
+block_eoe -> block_identifier eoe : '$1'.

 stab -> stab_expr : ['$1'].
-stab -> stab eol stab_expr : ['$3'|'$1'].
+stab -> stab eoe stab_expr : ['$3'|'$1'].

-stab_eol -> stab : '$1'.
-stab_eol -> stab eol : '$1'.
+stab_eoe -> stab : '$1'.
+stab_eoe -> stab eoe : '$1'.

 stab_expr -> expr : '$1'.
 stab_expr -> stab_op_eol stab_maybe_expr : build_op('$1', [], '$2').
@@ -276,8 +283,8 @@ stab_expr -> stab_parens_many when_op expr stab_op_eol stab_maybe_expr :
 stab_maybe_expr -> 'expr' : '$1'.
 stab_maybe_expr -> '$empty' : nil.

-block_item -> block_eol stab_eol : {?exprs('$1'), build_stab(reverse('$2'))}.
-block_item -> block_eol : {?exprs('$1'), nil}.
+block_item -> block_eoe stab_eoe : {?exprs('$1'), build_stab(reverse('$2'))}.
+block_item -> block_eoe : {?exprs('$1'), nil}.

 block_list -> block_item : ['$1'].
 block_list -> block_item block_list : ['$1'|'$2'].
@@ -1,10 +1,10 @@
 -module(elixir_quote).
 -export([escape/2, linify/2, linify/3, linify_with_context_counter/3, quote/4]).
-export([dot/6, tail_list/3, list/2]). %% Quote callbacks
+-export([dot/5, tail_list/3, list/2]). %% Quote callbacks

 -include("elixir.hrl").
 -define(defs(Kind), Kind == def; Kind == defp; Kind == defmacro; Kind == defmacrop).
-define(lexical(Kind), Kind == import; Kind == alias; Kind == '__aliases__').
+-define(lexical(Kind), Kind == import; Kind == alias; Kind == require).
 -compile({inline, [keyfind/2, keystore/3, keydelete/2, keyreplace/3, keynew/3]}).

 %% Apply the line from site call on quoted contents.
@@ -23,7 +23,8 @@ do_linify(Line, Key, {Receiver, Counter} = Var, {Left, Meta, Receiver})
    when is_atom(Left), is_list(Meta), Left /= '_' ->
  do_tuple_linify(Line, Key, Var, keynew(counter, Meta, Counter), Left, Receiver);

-do_linify(Line, Key, {_, Counter} = Var, {Lexical, [_|_] = Meta, [_|_] = Args}) when ?lexical(Lexical) ->
+do_linify(Line, Key, {_, Counter} = Var, {Lexical, [_|_] = Meta, [_|_] = Args})
+    when ?lexical(Lexical); Lexical == '__aliases__' ->
  do_tuple_linify(Line, Key, Var, keynew(counter, Meta, Counter), Lexical, Args);

 do_linify(Line, Key, Var, {Left, Meta, Right}) when is_list(Meta) ->
@@ -61,8 +62,8 @@ do_linify_meta(Line, Key, Meta) ->

 %% Some expressions cannot be unquoted at compilation time.
 %% This function is responsible for doing runtime unquoting.
-dot(Meta, Left, Right, Args, Context, File) ->
-  annotate(dot(Meta, Left, Right, Args), Context, File).
+dot(Meta, Left, Right, Args, Context) ->
+  annotate(dot(Meta, Left, Right, Args), Context).

 dot(Meta, Left, {'__aliases__', _, Args}, nil) ->
  {'__aliases__', Meta, [Left|Args]};
@@ -117,28 +118,29 @@ validate_list(List) when not is_list(List) ->
 argument_error(Message) ->
  error('Elixir.ArgumentError':exception([{message,Message}])).

-%% Annotates the AST with context and other info
+%% Annotates the AST with context and other info.
+%%
+%% Note we need to delete the counter because linify
+%% adds the counter recursively, even inside quoted
+%% expressions, so we need to clean up the forms to
+%% allow them to get a new counter on the next expansion.

-annotate({Def, Meta, [{H, M, A}|T]}, Context, File) when ?defs(Def) ->
-  %% Store the context information in the first element of the
-  %% definition tuple so we can access it later on.
-  MM = keystore(context, keystore(file, M, File), Context),
-  {Def, Meta, [{H, MM, A}|T]};
-annotate({{'.', _, [_, Def]} = Target, Meta, [{H, M, A}|T]}, Context, File) when ?defs(Def) ->
-  MM = keystore(context, keystore(file, M, File), Context),
-  {Target, Meta, [{H, MM, A}|T]};
+annotate({Def, Meta, [{H, M, A}|T]}, Context) when ?defs(Def) ->
+  {Def, Meta, [{H, keystore(context, M, Context), A}|T]};
+annotate({{'.', _, [_, Def]} = Target, Meta, [{H, M, A}|T]}, Context) when ?defs(Def) ->
+  {Target, Meta, [{H, keystore(context, M, Context), A}|T]};

-annotate({Lexical, Meta, [_|_] = Args}, Context, _File) when Lexical == import; Lexical == alias ->
+annotate({Lexical, Meta, [_|_] = Args}, Context) when ?lexical(Lexical) ->
  NewMeta = keystore(context, keydelete(counter, Meta), Context),
  {Lexical, NewMeta, Args};
-annotate(Tree, _Context, _File) -> Tree.
+annotate(Tree, _Context) -> Tree.

 %% Escapes the given expression. It is similar to quote, but
 %% lines are kept and hygiene mechanisms are disabled.
 escape(Expr, Unquote) ->
  {Res, Q} = quote(Expr, nil, #elixir_quote{
    line=true,
-    keep=false,
+    file=nil,
    vars_hygiene=false,
    aliases_hygiene=false,
    imports_hygiene=false,
@@ -221,11 +223,11 @@ do_quote({Name, Meta, ArgsOrAtom}, #elixir_quote{imports_hygiene=true} = Q, E) w
      keystore(import, keystore(context, Meta, Q#elixir_quote.context), Receiver)
  end,

-  Annotated = annotate({Name, NewMeta, ArgsOrAtom}, Q#elixir_quote.context, file(E, Q)),
+  Annotated = annotate({Name, NewMeta, ArgsOrAtom}, Q#elixir_quote.context),
  do_quote_tuple(Annotated, Q, E);

 do_quote({_, _, _} = Tuple, #elixir_quote{escape=false} = Q, E) ->
-  Annotated = annotate(Tuple, Q#elixir_quote.context, file(E, Q)),
+  Annotated = annotate(Tuple, Q#elixir_quote.context),
  do_quote_tuple(Annotated, Q, E);

 %% Literals
@@ -240,6 +242,15 @@ do_quote({Left, Right}, Q, E) ->
  {TRight, RQ} = do_quote(Right, LQ, E),
  {{TLeft, TRight}, RQ};

+do_quote(BitString, #elixir_quote{escape=true} = Q, _) when is_bitstring(BitString) ->
+  case bit_size(BitString) rem 8 of
+    0 ->
+      {BitString, Q};
+    Size ->
+      <<Bits:Size, Bytes/binary>> = BitString,
+      {{'<<>>', [], [{'::', [], [Bits, Size]}, Bytes]}, Q}
+  end;
+
 do_quote(Map, #elixir_quote{escape=true} = Q, E) when is_map(Map) ->
  {TT, TQ} = do_quote(maps:to_list(Map), Q, E),
  {{'%{}', [], TT}, TQ};
@@ -249,7 +260,7 @@ do_quote(Tuple, #elixir_quote{escape=true} = Q, E) when is_tuple(Tuple) ->
  {{'{}', [], TT}, TQ};

 do_quote(List, #elixir_quote{escape=true} = Q, E) when is_list(List) ->
-  % The improper case is pretty inefficient, but improper lists are are.
+  %% The improper case is a bit inefficient, but improper lists are rare.
  case reverse_improper(List) of
    {L}       -> do_splice(L, Q, E);
    {L, R}    ->
@@ -257,17 +268,38 @@ do_quote(List, #elixir_quote{escape=true} = Q, E) when is_list(List) ->
      {TR, QR} = do_quote(R, QL, E),
      {update_last(TL, fun(X) -> {'|', [], [X, TR]} end), QR}
  end;
+
+do_quote(Other, #elixir_quote{escape=true} = Q, _)
+    when is_number(Other); is_pid(Other); is_atom(Other) ->
+  {Other, Q};
+
+do_quote(Fun, #elixir_quote{escape=true} = Q, _) when is_function(Fun) ->
+  case (erlang:fun_info(Fun, env) == {env, []}) andalso
+       (erlang:fun_info(Fun, type) == {type, external}) of
+    true  -> {Fun, Q};
+    false -> bad_escape(Fun)
+  end;
+
+do_quote(Other, #elixir_quote{escape=true}, _) ->
+  bad_escape(Other);
+
 do_quote(List, Q, E) when is_list(List) ->
-    do_splice(lists:reverse(List), Q, E);
+  do_splice(lists:reverse(List), Q, E);

 do_quote(Other, Q, _) ->
  {Other, Q}.

 %% Quote helpers

+bad_escape(Arg) ->
+  Msg = <<"cannot escape ", ('Elixir.Kernel':inspect(Arg, []))/binary, ". ",
+          "The supported values are: lists, tuples, maps, atoms, numbers, bitstrings, ",
+          "pids and remote functions in the format &Mod.fun/arity">>,
+  error('Elixir.ArgumentError':exception([{message,Msg}])).
+
 do_quote_call(Left, Meta, Expr, Args, Q, E) ->
  All  = [meta(Meta, Q), Left, {unquote, Meta, [Expr]}, Args,
-          Q#elixir_quote.context, file(E, Q)],
+          Q#elixir_quote.context],
  {TAll, TQ} = lists:mapfoldl(fun(X, Acc) -> do_quote(X, Acc, E) end, Q, All),
  {{{'.', Meta, [elixir_quote, dot]}, Meta, TAll}, TQ}.

@@ -285,16 +317,19 @@ do_quote_tuple({Left, Meta, Right}, Q, E) ->
  {TRight, RQ} = do_quote(Right, LQ, E),
  {{'{}', [], [TLeft, meta(Meta, Q), TRight]}, RQ}.

-file(#{file := File}, #elixir_quote{keep=true}) -> File;
-file(_, _) -> nil.
+meta(Meta, Q) ->
+  file(line(Meta, Q), Q).

-meta(Meta, #elixir_quote{keep=true}) ->
+file(Meta, #elixir_quote{file=nil}) -> Meta;
+file(Meta, #elixir_quote{file=File}) -> [{file, File}|Meta].
+
+line(Meta, #elixir_quote{file=File}) when File /= nil ->
  [case KV of {line, V} -> {keep, V}; _ -> KV end || KV <- Meta];
-meta(Meta, #elixir_quote{line=true}) ->
+line(Meta, #elixir_quote{line=true}) ->
  Meta;
-meta(Meta, #elixir_quote{line=false}) ->
+line(Meta, #elixir_quote{line=false}) ->
  keydelete(line, Meta);
-meta(Meta, #elixir_quote{line=Line}) ->
+line(Meta, #elixir_quote{line=Line}) ->
  keystore(line, Meta, Line).

 reverse_improper(L) -> reverse_improper(L, []).
@@ -1,9 +1,10 @@
 %% Convenience functions used to manipulate scope and its variables.
 -module(elixir_scope).
-export([translate_var/4, build_var/2,
+-export([translate_var/4, build_var/2, context_info/1,
  load_binding/2, dump_binding/2,
  mergev/2, mergec/2, mergef/2,
-  merge_vars/2, merge_opt_vars/2
+  merge_vars/2, merge_opt_vars/2,
+  format_error/1
 ]).
 -include("elixir.hrl").

@@ -25,6 +26,7 @@ translate_var(Meta, Name, Kind, S) when is_atom(Kind); is_integer(Kind) ->

      case Exists andalso ordsets:is_element(Tuple, MatchVars) of
        true ->
+          warn_underscored_var(Line, S#elixir_scope.file, Name, Kind),
          {{var, Line, Current}, S};
        false ->
          %% We attempt to give vars a nice name because we
@@ -60,6 +62,19 @@ build_var(Key, S) ->
  Cnt = orddict:fetch(Key, New),
  {elixir_utils:atom_concat([Key, "@", Cnt]), Cnt, S#elixir_scope{counter=New}}.

+context_info(Kind) when Kind == nil; is_integer(Kind) -> "";
+context_info(Kind) -> io_lib:format(" (context ~ts)", [elixir_aliases:inspect(Kind)]).
+
+warn_underscored_var(Line, File, Name, Kind) ->
+  case atom_to_list(Name) of
+    "_@" ++ _ ->
+      ok; %% Automatically generated variables
+    "_" ++ _ ->
+      elixir_errors:form_warn([{line, Line}], File, ?MODULE, {unused_match, Name, Kind});
+    _ ->
+      ok
+  end.
+
 %% SCOPE MERGING

 %% Receives two scopes and return a new scope based on
@@ -138,3 +153,12 @@ dump_binding([{{Var, Kind} = Key, {InternalName,_}}|T], Binding, Acc) when is_at
 dump_binding([_|T], Binding, Acc) ->
  dump_binding(T, Binding, Acc);
 dump_binding([], _Binding, Acc) -> Acc.
+
+%% Errors
+
+format_error({unused_match, Name, Kind}) ->
+  io_lib:format("the underscored variable \"~ts\"~ts appears more than once in a "
+                "match. This means the pattern will only match if all \"~ts\" bind "
+                "to the same value. If this is the intended behaviour, please "
+                "remove the leading underscore from the variable name, otherwise "
+                "give the variables different names", [Name, context_info(Kind), Name]).
@@ -80,7 +80,7 @@
 -define(type_op(T1, T2),
  T1 == $:, T2 == $:).

-define(pipe_op(T1),
+-define(pipe_op(T),
  T == $|).

 tokenize(String, Line, #elixir_tokenizer{} = Scope) ->
@@ -118,15 +118,15 @@ tokenize([], EndLine, #elixir_tokenizer{terminators=[{Start, StartLine}|_]}, Tok

 % Base integers

-tokenize([$0,X,H|T], Line, Scope, Tokens) when (X == $x orelse X == $X), ?is_hex(H) ->
+tokenize([$0,$x,H|T], Line, Scope, Tokens) when ?is_hex(H) ->
  {Rest, Number} = tokenize_hex([H|T], []),
  tokenize(Rest, Line, Scope, [{number, Line, Number}|Tokens]);

-tokenize([$0,B,H|T], Line, Scope, Tokens) when (B == $b orelse B == $B), ?is_bin(H) ->
+tokenize([$0,$b,H|T], Line, Scope, Tokens) when ?is_bin(H) ->
  {Rest, Number} = tokenize_bin([H|T], []),
  tokenize(Rest, Line, Scope, [{number, Line, Number}|Tokens]);

-tokenize([$0,H|T], Line, Scope, Tokens) when ?is_octal(H) ->
+tokenize([$0,$o,H|T], Line, Scope, Tokens) when ?is_octal(H) ->
  {Rest, Number} = tokenize_octal([H|T], []),
  tokenize(Rest, Line, Scope, [{number, Line, Number}|Tokens]);

@@ -159,59 +159,44 @@ tokenize([$~,S,H|T] = Original, Line, Scope, Tokens) when ?is_sigil(H), ?is_upca

 % Char tokens

-tokenize([$?,$\\,P,${,A,B,C,D,E,F,$}|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E), ?is_hex(F) ->
-  Char = escape_char([$\\,P,${,A,B,C,D,E,F,$}]),
+tokenize([$?,$\\,$x,${,A,B,C,D,E,F,$}|T], Line, Scope, Tokens)
+    when ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E), ?is_hex(F) ->
+  Char = escape_char([$\\,$x,${,A,B,C,D,E,F,$}]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

-tokenize([$?,$\\,P,${,A,B,C,D,E,$}|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E) ->
-  Char = escape_char([$\\,P,${,A,B,C,D,E,$}]),
+tokenize([$?,$\\,$x,${,A,B,C,D,E,$}|T], Line, Scope, Tokens)
+    when ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D), ?is_hex(E) ->
+  Char = escape_char([$\\,$x,${,A,B,C,D,E,$}]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

-tokenize([$?,$\\,P,${,A,B,C,D,$}|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D) ->
-  Char = escape_char([$\\,P,${,A,B,C,D,$}]),
+tokenize([$?,$\\,$x,${,A,B,C,D,$}|T], Line, Scope, Tokens)
+    when ?is_hex(A), ?is_hex(B), ?is_hex(C), ?is_hex(D) ->
+  Char = escape_char([$\\,$x,${,A,B,C,D,$}]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

-tokenize([$?,$\\,P,${,A,B,C,$}|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B), ?is_hex(C) ->
-  Char = escape_char([$\\,P,${,A,B,C,$}]),
+tokenize([$?,$\\,$x,${,A,B,C,$}|T], Line, Scope, Tokens)
+    when ?is_hex(A), ?is_hex(B), ?is_hex(C) ->
+  Char = escape_char([$\\,$x,${,A,B,C,$}]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

-tokenize([$?,$\\,P,${,A,B,$}|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B) ->
-  Char = escape_char([$\\,P,${,A,B,$}]),
+tokenize([$?,$\\,$x,${,A,B,$}|T], Line, Scope, Tokens)
+    when ?is_hex(A), ?is_hex(B) ->
+  Char = escape_char([$\\,$x,${,A,B,$}]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

-tokenize([$?,$\\,P,${,A,$}|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A) ->
-  Char = escape_char([$\\,P,${,A,$}]),
+tokenize([$?,$\\,$x,${,A,$}|T], Line, Scope, Tokens)
+    when ?is_hex(A) ->
+  Char = escape_char([$\\,$x,${,A,$}]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

-tokenize([$?,$\\,P,A,B|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A), ?is_hex(B) ->
-  Char = escape_char([$\\,P,A,B]),
+tokenize([$?,$\\,$x,A,B|T], Line, Scope, Tokens)
+    when ?is_hex(A), ?is_hex(B) ->
+  Char = escape_char([$\\,$x,A,B]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

-tokenize([$?,$\\,P,A|T], Line, Scope, Tokens)
-    when (P == $x orelse P == $X), ?is_hex(A) ->
-  Char = escape_char([$\\,P,A]),
-  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);
-
-tokenize([$?,$\\,A,B,C|T], Line, Scope, Tokens)
-    when ?is_octal(A), A =< $3,?is_octal(B), ?is_octal(C) ->
-  Char = escape_char([$\\,A,B,C]),
-  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);
-
-tokenize([$?,$\\,A,B|T], Line, Scope, Tokens)
-    when ?is_octal(A), ?is_octal(B) ->
-  Char = escape_char([$\\,A,B]),
-  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);
-
-tokenize([$?,$\\,A|T], Line, Scope, Tokens)
-    when ?is_octal(A) ->
-  Char = escape_char([$\\,A]),
+tokenize([$?,$\\,$x,A|T], Line, Scope, Tokens)
+    when ?is_hex(A) ->
+  Char = escape_char([$\\,$x,A]),
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

 tokenize([$?,$\\,H|T], Line, Scope, Tokens) ->
@@ -219,6 +204,14 @@ tokenize([$?,$\\,H|T], Line, Scope, Tokens) ->
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

 tokenize([$?,Char|T], Line, Scope, Tokens) ->
+  case handle_char(Char) of
+    {Escape, Name} ->
+      Msg = io_lib:format("found ? followed by codepoint 0x~.16B (~ts), please use ~ts instead",
+                          [Char, Name, Escape]),
+      elixir_errors:warn(Line, Scope#elixir_tokenizer.file, Msg);
+    false ->
+      ok
+  end,
  tokenize(T, Line, Scope, [{number, Line, Char}|Tokens]);

 % Heredocs
@@ -306,10 +299,19 @@ tokenize([$:,T|Rest], Line, Scope, Tokens) when
 % End of line

 tokenize(";" ++ Rest, Line, Scope, []) ->
-  tokenize(Rest, Line, Scope, eol(Line, ';', []));
+  tokenize(Rest, Line, Scope, [{';', Line}]);

-tokenize(";" ++ Rest, Line, Scope, [Top|Tokens]) when element(1, Top) /= eol ->
-  tokenize(Rest, Line, Scope, eol(Line, ';', [Top|Tokens]));
+tokenize(";" ++ Rest, Line, Scope, [Top|_] = Tokens) when element(1, Top) /= ';' ->
+  tokenize(Rest, Line, Scope, [{';', Line}|Tokens]);
+
+tokenize("\\" = Original, Line, _Scope, Tokens) ->
+  {error, {Line, "invalid escape \\ at end of file", []}, Original, Tokens};
+
+tokenize("\\\n" = Original, Line, _Scope, Tokens) ->
+  {error, {Line, "invalid escape \\ at end of file", []}, Original, Tokens};
+
+tokenize("\\\r\n" = Original, Line, _Scope, Tokens) ->
+  {error, {Line, "invalid escape \\ at end of file", []}, Original, Tokens};

 tokenize("\\\n" ++ Rest, Line, Scope, Tokens) ->
  tokenize(Rest, Line + 1, Scope, Tokens);
@@ -318,10 +320,10 @@ tokenize("\\\r\n" ++ Rest, Line, Scope, Tokens) ->
  tokenize(Rest, Line + 1, Scope, Tokens);

 tokenize("\n" ++ Rest, Line, Scope, Tokens) ->
-  tokenize(Rest, Line + 1, Scope, eol(Line, newline, Tokens));
+  tokenize(Rest, Line + 1, Scope, eol(Line, Tokens));

 tokenize("\r\n" ++ Rest, Line, Scope, Tokens) ->
-  tokenize(Rest, Line + 1, Scope, eol(Line, newline, Tokens));
+  tokenize(Rest, Line + 1, Scope, eol(Line, Tokens));

 % Stand-alone tokens

@@ -461,22 +463,14 @@ tokenize([H|_] = String, Line, Scope, Tokens) when ?is_downcase(H); H == $_ ->
      Error
  end;

-% Ambiguous unary/binary operators tokens
-
-tokenize([Space, Sign, NotMarker|T], Line, Scope, [{Identifier, _, _} = H|Tokens]) when
-    ?dual_op(Sign),
-    ?is_horizontal_space(Space),
-    not(?is_space(NotMarker)),
-    NotMarker /= $(, NotMarker /= $[, NotMarker /= $<, NotMarker /= ${,                  %% containers
-    NotMarker /= $%, NotMarker /= $+, NotMarker /= $-, NotMarker /= $/, NotMarker /= $>, %% operators
-    Identifier == identifier ->
-  Rest = [NotMarker|T],
-  tokenize(Rest, Line, Scope, [{dual_op, Line, list_to_atom([Sign])}, setelement(1, H, op_identifier)|Tokens]);
-
 % Spaces

 tokenize([T|Rest], Line, Scope, Tokens) when ?is_horizontal_space(T) ->
-  tokenize(strip_horizontal_space(Rest), Line, Scope, Tokens);
+  handle_space_sensitive_tokens(strip_horizontal_space(Rest), Line, Scope, Tokens);
+tokenize([T|Rest] = Original, Line, _Scope, Tokens) when ?is_invalid_space(T) ->
+  Message = io_lib:format("invalid space character U+~.16B before: ", [T]),
+  {error, {Line, lists:flatten(Message), until_eol(Rest)}, Original, Tokens};
+
 tokenize(T, Line, _Scope, Tokens) ->
  {error, {Line, "invalid token: ", until_eol(T)}, T, Tokens}.

@@ -497,8 +491,20 @@ until_eol("\n" ++ _)   -> [];
 until_eol([])          -> [];
 until_eol([H|T])       -> [H|until_eol(T)].

+handle_char(7)   -> {"\\a", "alert"};
+handle_char($\b) -> {"\\b", "backspace"};
+handle_char($\d) -> {"\\d", "delete"};
+handle_char($\e) -> {"\\e", "escape"};
+handle_char($\f) -> {"\\f", "form feed"};
+handle_char($\n) -> {"\\n", "newline"};
+handle_char($\r) -> {"\\r", "carriage return"};
+handle_char($\s) -> {"\\s", "space"};
+handle_char($\t) -> {"\\t", "tab"};
+handle_char($\v) -> {"\\v", "vertical tab"};
+handle_char(_)  -> false.
+
 escape_char(List) ->
-  << Char/utf8 >> = elixir_interpolation:unescape_chars(list_to_binary(List)),
+  <<Char/utf8>> = elixir_interpolation:unescape_chars(list_to_binary(List)),
  Char.

 %% Handlers
@@ -590,11 +596,25 @@ handle_call_identifier(Rest, Line, Op, Scope, Tokens) ->
  Token = check_call_identifier(identifier, Line, Op, Rest),
  tokenize(Rest, Line, Scope, [Token|add_token_with_nl({'.', Line}, Tokens)]).

+% ## Ambiguous unary/binary operators tokens
+handle_space_sensitive_tokens([Sign, NotMarker|T], Line, Scope, [{Identifier, _, _} = H|Tokens]) when
+    ?dual_op(Sign),
+    not(?is_space(NotMarker)),
+    NotMarker /= $(, NotMarker /= $[, NotMarker /= $<, NotMarker /= ${,                  %% containers
+    NotMarker /= $%, NotMarker /= $+, NotMarker /= $-, NotMarker /= $/, NotMarker /= $>, %% operators
+    Identifier == identifier ->
+  Rest = [NotMarker|T],
+  tokenize(Rest, Line, Scope, [{dual_op, Line, list_to_atom([Sign])}, setelement(1, H, op_identifier)|Tokens]);
+
+handle_space_sensitive_tokens(String, Line, Scope, Tokens) ->
+  tokenize(String, Line, Scope, Tokens).
+
 %% Helpers

-eol(_Line, _Mod, [{',',_}|_] = Tokens)   -> Tokens;
-eol(_Line, _Mod, [{eol,_,_}|_] = Tokens) -> Tokens;
-eol(Line, Mod, Tokens) -> [{eol,Line,Mod}|Tokens].
+eol(_Line, [{';',_}|_] = Tokens) -> Tokens;
+eol(_Line, [{',',_}|_] = Tokens) -> Tokens;
+eol(_Line, [{eol,_}|_] = Tokens) -> Tokens;
+eol(Line, Tokens) -> [{eol,Line}|Tokens].

 unsafe_to_atom(Part, Line, #elixir_tokenizer{}) when
    is_binary(Part) andalso size(Part) > 255;
@@ -821,7 +841,7 @@ check_call_identifier(_Kind, Line, Atom, [$(|_]) -> {paren_identifier, Line, Ato
 check_call_identifier(_Kind, Line, Atom, [$[|_]) -> {bracket_identifier, Line, Atom};
 check_call_identifier(Kind, Line, Atom, _Rest)   -> {Kind, Line, Atom}.

-add_token_with_nl(Left, [{eol,_,newline}|T]) -> [Left|T];
+add_token_with_nl(Left, [{eol,_}|T]) -> [Left|T];
 add_token_with_nl(Left, T) -> [Left|T].

 %% Error handling
@@ -945,7 +965,6 @@ keyword('nil')   -> token;
 keyword('not')    -> unary_op;
 keyword('and')    -> and_op;
 keyword('or')     -> or_op;
-keyword('xor')    -> or_op;
 keyword('when')   -> when_op;
 keyword('in')     -> in_op;

@@ -72,7 +72,7 @@ translate({fn, Meta, Clauses}, S) ->

 %% Cond

-translate({'cond', _Meta, [[{do, Pairs}]]}, S) ->
+translate({'cond', CondMeta, [[{do, Pairs}]]}, S) ->
  [{'->', Meta, [[Condition], Body]}|T] = lists:reverse(Pairs),
  Case =
    case Condition of
@@ -88,7 +88,7 @@ translate({'cond', _Meta, [[{do, Pairs}]]}, S) ->
        Acc = {'case', Meta, [Condition, [{do, [Truthy, Falsy]}]]},
        build_cond_clauses(T, Acc, Meta)
    end,
-  translate(Case, S);
+  translate(replace_case_meta(CondMeta, Case), S);

 %% Case

@@ -195,18 +195,16 @@ translate({Name, Meta, Args}, S) when is_atom(Name), is_list(Meta), is_list(Args
  if
    S#elixir_scope.context == match ->
      compile_error(Meta, S#elixir_scope.file,
-                    "cannot invoke function ~ts/~B inside match", [Name, length(Args)]);
+                    "cannot invoke local ~ts/~B inside match", [Name, length(Args)]);
    S#elixir_scope.context == guard ->
      Arity = length(Args),
      File  = S#elixir_scope.file,
      case Arity of
        0 -> compile_error(Meta, File, "unknown variable ~ts or cannot invoke "
-                           "function ~ts/~B inside guard", [Name, Name, Arity]);
+                           "local ~ts/~B inside guard", [Name, Name, Arity]);
        _ -> compile_error(Meta, File, "cannot invoke local ~ts/~B inside guard",
                           [Name, Arity])
      end;
-    S#elixir_scope.function == nil ->
-      compile_error(Meta, S#elixir_scope.file, "undefined function ~ts/~B", [Name, length(Args)]);
    true ->
      Line = ?line(Meta),
      {TArgs, NS} = translate_args(Args, S),
@@ -249,7 +247,7 @@ translate({{'.', _, [Left, Right]}, Meta, Args}, S)
              {atom, Line, 'true'}},
            {map_field_assoc, Line,
              {atom, Line, key},
-              {atom, Line, TRight}},
+              TRight},
            {map_field_assoc, Line,
              {atom, Line, term},
              TVar}]},
@@ -387,6 +385,11 @@ build_cond_clauses([{'->', NewMeta, [[Condition], Body]}|T], Acc, OldMeta) ->
 build_cond_clauses([], Acc, _) ->
  Acc.

+replace_case_meta(Meta, {'case', _, Args}) ->
+  {'case', Meta, Args};
+replace_case_meta(_Meta, Other) ->
+  Other.
+
 build_truthy_clause(Meta, Condition, Body) ->
  case elixir_utils:returns_boolean(Condition) of
    true ->
@@ -46,7 +46,7 @@ read_link_type(File) ->
 relative_to_cwd(Path) ->
  case elixir_compiler:get_opt(internal) of
    true  -> Path;
-    false -> 'Elixir.String':to_char_list('Elixir.Path':relative_to_cwd(Path))
+    false -> 'Elixir.Path':relative_to_cwd(Path)
  end.

 characters_to_list(Data) when is_list(Data) ->
@@ -20,7 +20,9 @@ defmodule AccessTest do
  test "for nil" do
    assert nil[:foo] == nil
    assert Access.get(nil, :foo) == nil
-    assert Access.get_and_update(nil, :foo, fn nil -> {:ok, :bar} end) == {:ok, :bar}
+    assert_raise ArgumentError, "could not put/update key :foo on a nil value", fn ->
+      Access.get_and_update(nil, :foo, fn nil -> {:ok, :bar} end)
+    end
  end

  test "for keywords" do
--- a/Show More
+++ b/Show More