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TypeError: 'type' object is not subscriptable

Not confirmed yet · posted

Cause

builtin generics such as list[int] and dict[str, int] arrived in Python 3.9 (PEP 585); 3.8 evaluates the annotation at def time and list has no __class_getitem__.

Fix

risk: low

+from typing import Dict, List-def total(xs: list[int]) -> dict[str, int]:+def total(xs: List[int]) -> Dict[str, int]:

Don’t try

add from __future__ import annotations and keep list[int] in aliases, cast() or isinstance() — the import only defers annotations; runtime expressions such as Ints = list[int] still raise the same TypeError on 3.8.

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