Hi, the Prelude docs found via http://haskell.org/hoogle/hoodoc.cgi?module=Prelude&name=Functor&mode=class claim that there is an instance Functor ((,) a) And yet, I get (in GHC, but similarly in Hugs): Prelude> fmap (+1) (undefined,2) <interactive>:1:0: No instance for (Functor ((,) a)) arising from use of `fmap' at <interactive>:1:0-22 Possible fix: add an instance declaration for (Functor ((,) a)) In the expression: fmap ((+ 1)) (undefined, 2) In the definition of `it': it = fmap ((+ 1)) (undefined, 2) What do I have to import to get the Functor ((,) a) instance? (Of course, I can define it myself, but this is not the point.) Thanks, Janis. -- Dr. Janis Voigtlaender http://wwwtcs.inf.tu-dresden.de/~voigt/ mailto:voigt@tcs.inf.tu-dresden.de