MyPy doesn't understand types.ModuleType

[wittekm]

I tried doing # type: (module) -> str and MyPy was okay with it, but our linter was not. Some discussion in our Slack channel:

Guido:
From types import ModuleType?
Oh wow. Please file a bug. Mypy uses builtins.module but that doesn't exist so can't be used at runtime; types.ModuleType exists but mypy doesn't understand it.

David Fisher:
oh interesting
we have a "class module" entry in builtins
with the comment # TODO not defined in builtins!

[gvanrossum]

Yeah, so apparently when mypy sees a variable that's a module (as opposed to just an import statement) it gives it the type builtins.module even though that doesn't exist. The actual type of module objects is types.ModuleType. This would probably be easy to fix.