typed dict literals¶

a dict-shaped expression in an annotation position is a TypedDict:

def get_user() -> {"name": str, "age": int}: ...

shape identity ignores key order — {"a": int, "b": str} and {"b": str, "a": int} are the same type

typing_extensions is a runtime requirement of any module that contains a typed-dict-literal annotation (the generated type uses PEP 728 closed/extra_items features that aren't yet in typing.TypedDict)

closed by default, **: T for extra items¶

dict literal types are closed by default, so extra keys are rejected. a **: T entry switches that to "extra keys allowed, must match T":

a: {"key": int}              # closed — extra keys rejected
b: {"key": int, **: str}     # extra keys allowed, must be str

nested shapes¶

nested typed-dict literals work transparently:

addr: {"city": str, "zip": str}
user: {"name": str, "address": {"city": str, "zip": str}}

scope¶

the rewrite fires only in annotation positions — function parameter and return annotations, variable annotations, and nested type arguments. dict expressions in value positions (real dicts) are never affected