[Haskell-cafe] Inscrutable error message from PolyKinds (should it be in GHC202X?)

Tom Ellis tom-lists-haskell-cafe-2017 at jaguarpaw.co.uk
Mon Jan 23 19:11:36 UTC 2023


On Mon, Jan 23, 2023 at 02:18:22PM +0000, Tom Ellis wrote:
> On Mon, Jan 23, 2023 at 03:05:52PM +0100, J. Reinders wrote:
> > More examples of GHC2021 inclusion of PolyKinds confusing people:
> > 
> > * https://discourse.haskell.org/t/different-typeable-constraints-behaviour-in-ghc2021-haskell2010/4606?u=jaror
> > * https://stackoverflow.com/q/72329476/15207568
> > 
> > Sometimes it even causes errors where there were none before.
> 
> Great evidence!  Thanks for linking it.

A related discussion amongst the GHC steering committee:

https://mail.haskell.org/pipermail/ghc-steering-committee/2022-July/002812.html


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