chore: make the 'P' type var contravariant - #2995
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It's used as a type var for function arguments. This will allow for
constructs like defining a function `foo` that takes a union of request types:
def foo(r: Request[A, X] | Request[B, X]) -> X:
...
The foo function takes either an object of type `Request[A,X]` or an object
of type `Request[B,X]` and in both cases will return an object of type `X`.
rchl
approved these changes
Jul 22, 2026
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(I'm porting some self-contained bits from the feat/asyncio branch so that PR becomes a bit smaller.)
It's used as a type var for function arguments. This will allow for constructs like defining a function
foothat takes a union of request types:def foo(r: Request[A, X] | Request[B, X]) -> X:
...
The foo function takes either an object of type
Request[A,X]or an object of typeRequest[B,X]and in both cases will return an object of typeX.