partial() on python types?

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I often use type hints to help document code & occasionally when the type signatures are too complex & repeatedly used I alias them like this:

MyType = Dict[Tuple[int,...], float]  # ex: cluster & score.

Is there a way in python to parametrize type parts? A common use case is when I want to describe functions returning generators. For instance the Generator[int, None, None] notation works but the unused None details could be hidden in a new type.

Does there exists something like partial functions on types where we can “lock in” some of the sub type parameters? Or perhaps this is doable via Generics? Conceptually I’m thinking of something like this:

MyGenType[int] = functools.partial(Generator, None, None) # pseudo code!

This did it:

from typing import Generator, TypeVar

T = TypeVar("T")
MyGenType = Generator[T, None, None]

def fn(n: int) -> MyGenType[str]:
    return (str(_) for _ in range(n))

list(fn(3)) # ['0', '1', '2']

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