[Haskell-cafe] instance Eq (a -> b)

Why isn't there an instance Eq (a -> b) ? allValues :: (Bounded a,Enum a) => [a] allValues = enumFrom minBound instance (Bounded a,Enum a,Eq b) => Eq (a -> b) where p == q = fmap p allValues == fmap q allValues Of course, it's not perfect, since empty types are finite but not Bounded. One can nevertheless make them instances of Bounded with undefined bounds, and have enumFrom and friends always return the empty list. It seems one should also be able to write instance (Bounded a,Enum a) => Traversable (a -> b) where ??? But this turns out to be curiously hard. -- Ashley Yakeley