ParamSpec: No support for adding keyword-only argument

I've been looking through PEP 612 but I just wasn't able to find any way to implement behavior that would allow me to do this:

P = ParamSpec("P")
R = TypeVar("R")

def foo(f: Callable[P, R]) -> Callable[P, List[R]]:  # Here, the parameters are actually P + optional kw-only int x = 3
    def inner(*args: P.args, x: int = 3, **kwargs: P.kwargs) -> List[R]:
        results = []
        for _ in range(x):
          ret = f(*args, **kwargs)
          results.append(ret)
        return results
    return inner

@foo
def bar(p: int):
    return p + 2

bar(5)  # Acceptable
bar(5, x=8)  # Should also be Acceptable

Proposed solution:

Callable[[P.args, x: int = 3, P.kwargs], List[R]]

EDIT: I didn't notice that this was already in rejected alternatives section (I didn't scroll that far), however I still think an implementation like this would be worth adding since I have already encountered the need for this twice and there's simply absolutely no way to handle it.

I'm fine with the proposed syntax suggestion of

Concatenate[("x", int), P]

Though it didn't mention anything about default values, but those could just be handled by a third value in that tuple. It would probably be a lot easier to implement than my proposed suggestion, though to be fair, at least to me, my suggestion looks a bit cleaner.

Commencez par lire les alternatives rejetées de PEP 612 ainsi que les spécifications existantes de ParamSpec et Concatenate. Comme l’issue ne nomme aucun fichier d’implémentation ni test, identifiez d’abord les points d’entrée pertinents de typing-spec ; la tâche est considérée comme terminée lorsqu’une syntaxe faisant consensus et un comportement défini pour les paramètres keyword-only optionnels sont établis.