Cannot infer type argument 1 of Nothing.and_then + other type issues with Maybe

[ericgj]

Minimal example:

from pfun.maybe import Maybe, Just, Nothing

def test_and_then() -> Maybe[int]:
   nope: Maybe[int] = Nothing()
   return nope.and_then(lambda x: Just(x + 1))

def test_map() -> Maybe[int]:
   nope: Maybe[int] = Nothing()
   return nope.map(lambda x: x + 1)

The first one results in:
Cannot infer type argument 1 of "and_then" of "Nothing"

The second:
Returning Any from function declared to return int

The second one seems to be because it is picking up the signature of the ABC: Maybe_.map.

I am using the pfun.mypy_plugin.

Thanks for this very promising library!

[suned]

Thanks for the report!

The first one is likely because of limitations of type inference of lambdas in mypy itself, so not sure there is much to do there unfortunately.

I'll look into the second one, might be as you say because of the ABC. I may remove that, since it doesn't really make any sense anyway.