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type not inferred in application of higher-order function to a generic function #1507
Description
from typing import TypeVar, Callable
S = TypeVar('S')
def apply(f: Callable[[int], S]) -> S: pass
def g(x: S) -> S: pass
y = apply(g) # E: Argument 1 to "apply" has incompatible type Callable[[S], S]; expected Callable[[int], S]
reveal_type(y) # E: Revealed type is 'S`-1'
The call to apply should type check, with both types S and the type of y being int.
I encountered this sort of situation in mypy/codec/pytokenize.py in the lines
tokenprog, pseudoprog, single3prog, double3prog = map(
re.compile, (Token, PseudoToken, Single3, Double3))
#1471 was an attempt to fix this, but since it fixes this case but not #1506, I'm filing these as two related but distinct issues.
Activity
davidhalter commentedon Jan 21, 2024
This is working now. So I feel like this issue should be closed.
See https://mypy-play.net/?mypy=latest&python=3.12&gist=2265ae341b2994f28577afc8788c0879
hauntsaninja commentedon Jan 21, 2024
Thanks!