Allow `float("inf")` and `float("-inf")` in literals

I have been frequently using positive and negative infinity as default values for values that should otherwise be ints. Because of Python's duck typing this is a convenient pattern that sometimes allows reducing some special-casing logic.

def less_than(value: int, limit: int | None) -> bool:
    if limit is None:
        return True
    return value < limit

vs

def less_than(value: int, limit: int | Literal[float("inf")]) -> bool:
    return value < limit

Would it be feasible to special-case the expressions float("inf") and float("-inf") and make type-checkers regard them as literal values, even though they aren't strictly speaking language-level literals?

For posterity, PEP 586 mentions this with:

Representing Literals of infinity or NaN in a clean way is tricky; real-world APIs are unlikely to vary their behavior based on a float parameter.

So I guess what I'm asking here is: am I an odd duckling or could it be worth considering +/- infinity as legal values in literal types?

Inizia leggendo la discussione di PEP 586 sui parametri Literal non validi e i 21 commenti su questa issue. Determina se la comunità del typing ha raggiunto una decisione sul trattare float("inf") e float("-inf") come valori literal; il lavoro sarebbe completato solo con una specifica condivisa e con l’identificazione delle modifiche necessarie ai type-checker, elementi che l’issue non fornisce.