Re: [Haskell-cafe] Mystery: constructor type applications differ from signatures

29 Oct 2022


      On Sat, Oct 29, 2022 at 01:12:15PM +0100, Tom Ellis wrote:
...
-- Works fine
isMaybeF :: forall k (a :: k). FunRep a -> FromType
isMaybeF = \case
  AppK @_ @f t (Proxy @_ @g :: Proxy h) ->
    case t of
      IsType -> FromType @f
Correction: this one is the one that doesn't work fine.  The error is
"Couldn't match kind ‘k’ with ‘*’".