On Dec 23, 2021, at 17:09, Guido van Rossum <guido@python.org> wrote:
Mark's proposal was ``` @Callable def func(params): pass ``` My question is, why does it need `@Callable`? Lukasz proposed just using any (undecorated) function, with the convention being that the body is `...` (to which I would add the convention that the function *name* be capitalized, since it is a type). My question (for Mark, or for anyone who supports `@Callable`) is why bother with the decorator. It should be easy to teach a type checker about this:
``` def SomeFn(x: float) -> int: ...
def twice(f: SomeFn) -> SomeFn: return lambda x: f(f(x)) ```
That seems pretty intuitive to me. The conventions you mention would be just that though, right? I.e. `pass` could be used, but whatever the body is it would be ignored for type checking `twice()` in this case, right? -Barry