On 15/08/12 19:02, Edward Kmett wrote: > I'm not a huge fan of (.:), but you insist on adding it, please generalize it to > fmap.fmap. > > (.:) :: (Functor f, Functor g) => (a -> b) -> f (g a) -> f (g b) > > This subsumes the other use case. For the love of Categories, please don't go down this road. fmap is not the proper generalization of (.). Twan