PEP 718

A Python Enhancement Proposal I co-authored with James Hilton-Balfe, sponsored by Guido van Rossum, the creator of Python. A PEP is how changes to the Python language are proposed and discussed. This one makes functions subscriptable, so a generic function can be given its type parameters explicitly, the same way a generic class can:

def my_list[T](arr: Iterable[T]) -> list[T]: ...

my_list[int]()  # today: TypeError

This helps where type inference can't work out the type, keeps functions and classes consistent, and leaves room for future features like monomorphisation. Status: Draft, targeting Python 3.15.