Make the 2 last parameters for typing.Generator optional

[sametmax]

If I use:

Generator[int]

mypy complains:

error: "Generator" expects 3 type arguments, but 1 given

I can silence mypy by doing:

Generator[int, None, None]

But given that the majority of generators just yield, rarely return or send, I think it would make sense to allow the last 2 parameters to have a default value of None.

[emmatyping]

This issue is probably better suited to be discussed in the typing repo https://github.com/python/typing

[JukkaL]

Is there a reason you can't use Iterator[int] as the return type?

[zeth]

Is there a reason you can't use Iterator[int] as the return type?

Because the type is a Generator. Are we annotating the types or not?

[hauntsaninja]

We are annotating the types, all three of them, yield send and return ;-) For everything else, there's Iterator.

While I don't think this is a compelling case since there's a solution that works perfectly well, I'm sympathetic to the idea of defaults for generic types in general. The forum to take that issue up is the typing-sig mailing list or https://github.com/python/typing, not here