See #21822 (https://gitlab.haskell.org/ghc/ghc/-/issues/21822) and #14190 <https://gitlab.haskell.org/ghc/ghc/-/issues/14190>/#16627 <https://gitlab.haskell.org/ghc/ghc/-/issues/16627>! Simon On Wed, 6 Jul 2022 at 15:01, Richard Eisenberg <lists@richarde.dev> wrote:
On Jul 6, 2022, at 8:00 AM, Chris Dornan <chris@chrisdornan.com> wrote:
Richard are you satisfied that my example program is invalid under PolyKinds?
Yes. But I think as we've started to piece together, the real problem in this example is a missing superclass constraint on Typeable, not a fundamental shortcoming of PolyKinds. (I do acknowledge that extra polymorphism can introduce trouble, but given the fact that PolyKinds introduces parametric polymorphism -- unlike the ad hoc polymorphism of OverloadedStrings -- I think these cases should be rare.)
It would be interesting to see whether fixing Typeable in this way fixes other problems Chris has run into.
Richard