I would see support of all argument kinds support in any proposal for a new callable: positional only args, named args, keyword-only, *args and **kwargs.
The exact notation in probably less important than missing functionality.
Hm, but using Protocol you can already express every callable type. We could duplicate all of the complexity of 'def' parameter lists into the type notation, but it would be very complex. So this requirement is at least debatable (I'm not actually sure how I feel about it).
Don't get me wrong please. I'm not the typing system developer (while use typing every day in my code).
You can consider this email as end-user feedback.
I have a lot of code that uses `Callable` annotation; it is a natural way of annotating any callable, isn't it.
Sometimes `Callable` doesn't work. For example, I cannot annotate a function that accepts a keyword-only argument.
Sure, I can use Protocol but it doesn't feel natural and requires more code lines, especially if the Protocol is used once or twice.
Also, Protocol adds `self` to methods which looks at least confusing when I annotate plain callables which naturally don't belong to any class:
def __call__(self, /, arg: int) -> str: ...
Moreover, I recall a pull request to only of my libraries that had something similar to:
def __call__(self_, /, self: Class, arg: int) -> str: ...