[Haskell-cafe] lawless instances of Functor

Hi, I'm trying to get a deep feeling of Functors (and then pointed Functors, Applicative Functors, etc.). To this end, I try to find lawless instances of Functor that satisfy one law but not the other. I've found one instance that satisfies fmap (f.g) = fmap f . fmap g but not fmap id = id: data Foo a = A | B instance Functor Foo where fmap f A = B fmap f B = B -- violates law 1 fmap id A = B -- respects law 2 fmap (f . g) A = (fmap f . fmap g) A = B fmap (f . g) B = (fmap f . fmap g) B = B But I can't come up with an example that satifies law 1 and not law 2. I'm beginning to think this isn't possible but I didn't read anything saying so, neither do I manage to prove it. I'm sure someone knows :) Paul