Andrei Borzenkov authored Jun 13, 2023 and Marge Bot committed Jun 27, 2023

Arity inference in type declarations was introduced
as a workaround for the lack of @k-binders.

They were added in 4aea0a72, so I simplified all
of this by simply removing arity inference altogether.

This is part of GHC Proposal #425 "Invisible binders in type
declarations".