I really don't understand what is going on here. ...

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{-# LANGUAGE TypeFamilies #-} {-# LANGUAGE AllowAmbiguousTypes #-}

{-

src/Games/Ambiguous.hs:15:16: error: … • Couldn't match expected type ‘SubAmbi a0’ with actual type ‘SubAmbi a’ NB: ‘SubAmbi’ is a non-injective type family The type variable ‘a0’ is ambiguous

-}

Hi Henry, both replies you've received are excellent, I won't expand on them. I am interested in how you got into such a pickle in the first place: Why set `AllowAmbiguousTypes`? Did you understand what that means? Did you think it odd that despite having that set, you get error `type variable ... is ambiguous`? There are ways to achieve what you want without `AllowAmbiguousTypes` nor `TypeApplications`, but that would need a rather different design. So what lead you into this design? AntC