I've heard contravariant functors referred to as "cofunctors", and I've also heard objections to that term. As I'm preparing to release some libraries using contravariant functors, I'd appreciate hearing preferences and/or reasons. For instance, another name would be "Contrafunctor". -- | Contravariant functors. often useful for /acceptors/ (consumers, -- sinks) of values. class Cofunctor acc where cofmap :: (a -> b) -> (acc b -> acc a) Thanks, - Conal