More annoying for our codebase is the inability to specify optional/default arguments with closures. We often use functions that return other functions and you can't persist the "optional state" without using a protocol. It would be great just to match the current state of vanilla defs with optional params.

For example:

  def make_fun1(a: int) -> Callable[[int, Optional[int]], str]:
      def fun(b: int, c: Optional[int] = None) -> str:
          if c:
              b += c
          return f"{a+b}"

      return fun

  fun = make_fun(1)
  fun(2)

Will give you `Too few arguments` for `fun(2)`

You can fix this with something like:

  class FunC(Protocol):
      def __call__(self, b: int, c: Optional[int] = None) -> str: ...

  def make_fun(a: int) -> FunC:  ...

But that that seems like unnecessary overhead, because the non-nested def case can happily understand the optional parameter.

> I've personally never missed the ability to add keyword arguments to a Callable. If you want to anyway, I understand that at least mypy has syntax for this

Neat, I didn't realize this. This is far from desirable, but nice to know it's possible.

> Many syntax niceities will be introduced in upcoming Python releases. From the article:

I mean, typing out "Union" and "Option" or even having to import generic types from the typing module aren't really the syntactic pain points I was referring to. It's more like "Where do I define the TypeVar for a generic method on a class? Do I define it inside of the class or at the top-level module? In either case, if I reference that variable in another method, does it imply that these two types are the same? No doubt there are answers, but Python is the only language in which I have to navigate these kinds of questions. Similarly, having to create a protocol for kwarg callbacks seems really heavy. These are the kinds of things I would like to see improved.

> Dropbox has dedicated engineers maintaining mypy. And of course a few volunteers such as myself. And Guido. :)

Yes, I didn't mean to suggest there was no investment, only that the progress seems really slow (also, I didn't realize Guido was a volunteer? I thought he was employed by DropBox to work on Python). How long have recursive types been in a holding pattern, for example? I don't mean to disrespect you or any of the other maintainers--no doubt you're doing great work.