12.10.21 00:03, Guido van Rossum пише:
> But if I see
>
> def Comparison(a: T, b: T) -> Literal[-1, 0, 1]:
> ...
>
> my first thought is that it's a comparison function that someone hasn't
> finished writing yet, not a function type -- since if it did have at
> least one line of code in the body, it *would* be that.
I agree. There are also problems with variables substitution (indexing),
union (operator "|") and introspection. We would need to add
__getitem__, __or__, __args__, __parameters__ etc to all functions.
There may be also conflicts with NewType which returns a callable.
But can it be expressed via Protocol?
class Comparison(Protocol, Generic[T]):
def __call__(self, /, a: T, b: T) -> Literal[-1, 0, 1]: ...
Then we can just add a decorator which turns a function into class:
@functype
def Comparison(a: T, b: T) -> Literal[-1, 0, 1]:
...
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