[Haskell-cafe] Functional dependence nightmare

[Stephen Tetley]

Hi Edgar

What did you try?

My intuition is that this specific bit (there may be other problems)
is because the type checker is introducing a new type variable. Thus
you don't actually want the type operator (~) to say the new type
variable is equal to the type variable in the function signature, you
want to use scoped type variables so that the local type annotation is
*the same type* type variable.

Best wishes

Stephen