DIfferent Typeable constraints behaviour in GHC2021 & Haskell2010
Summary
The issue and its discussion is documented in: https://discourse.haskell.org/t/different-typeable-constraints-behaviour-in-ghc2021-haskell2010/4606
In brief, using Typeable and PolyKinds (which is enabled in GHC2021) triggers a interesting head-scratching issue that results a type error during complication.
Steps to reproduce
See https://discourse.haskell.org/t/different-typeable-constraints-behaviour-in-ghc2021-haskell2010/4606
Expected behavior
The code should not fail the complication when GHC2021 is enabled.
But if it has to, at least specifying what's the most sensible way of augmenting the code, and document it as a GHC 9.x breaking change.
Environment
- GHC version used: 9.2.2, installed using GHCUP
Optional:
- Operating System: Ubuntu / Windows 11
- System Architecture: x86