I encountered another bug, the__repr__ needs to be updated as well:

>>> ca.Callable[[int, P], int][P][int]collections.abc.Callable[[int, (<class 'int'>,)], int]

EDIT: THIS MIGHT NOT BE A BUG, AS ITS AN INVALID USE. PLEASE IGNORE THIS@sobolevn

@Fidget-Spinner I would like to move allrepr related problems to another PR if that possible :)

I've only touched params substitution here.

Wait a moment, this is not aboutrepr, this is an__args__ containing atuple 😒

>>>ca.Callable[[int,P],int][P].__args__(<class'int'>,~P,<class'int'>)>>>ca.Callable[[int,P],int][P][int].__args__(<class'int'>, (<class'int'>,),<class'int'>)

Funny thing, I just removed this code from_collections_abc.py as an experiment:

if (len(self.__parameters__)==1and_is_param_expr(self.__parameters__[0])anditemandnot_is_param_expr(item[0])):item= (item,)

All tests still pass :)

🤯

I am going to close this for now, I will add new tests in other PRs, because this one has a big unrelated history.