Hi Haskellers, I'm wondering why, given that functions and referential transparency are first class citizens in haskell, it isn't possible to write a mapping function this way: f1 :: a -> b f2 :: a -> b f3 :: c -> a -> b map :: (a -> b) -> T a -> T b map f1 = anEquivalentOfF1InTCategory map f2 = anEquivalentOfF2InTCategory map f3 $ c = anEquivalentOfF3withCInTCategory map unknown = aGenericMapInTCategory Is it "just" the implementation complexity of the feature in ghc that prevents this? Or is it "conceptually" wrong? At a first look, I thought that most of complexity here should be related to function's equality, but than I thought that the function full name should uniquely map from the category of meanings in the programmer mind to the category of implementations available to the compiler's. Giacomo