The Functor type class generalizes Applicative and Monad, but it also generalizes Foldable and Traversable, which are in Data.Foldable and Data.Traversable. Since some Applicative functors are also "data" (as opposed to operators), like the list functor, it seems like a reasonable compromise to put it in Data.Functor. Louis Wasserman wasserman.louis@gmail.com http://profiles.google.com/wasserman.louis