If A depends on B and B depends on C, all as runtime
dependencies, and C changes, there is no change that
can happen in C that will change the result of running
the checker on A.
This could change in the future in two ways:
1. If we introduce inference of return types, then we
need to infer and check the types for A again. This
may be an argument for not introducing inference of
return types (only of patterns and guards)
2. We will need to track "type exports" once we introduce
type aliases
José Valim
7890e56c3c