I'm running ghc-6.7.20070802 and getting a new error message that didn't show up with ghc-6.6. Code: -- | Pairing for unary type constructors. newtype Pair1 f g a = Pair1 {unPair1 :: (f a, g a)} deriving (Eq, Ord, Show) Error message: src/Data/Tupler.hs:26:0: No instances for (Show (g a), Show (f a)) arising from the 'deriving' clause of a data type declaration at src/Data/Tupler.hs:(26,0)-(27,25) Possible fix: add an instance declaration for (Show (g a), Show (f a)) When deriving the instance for (Show (Pair1 f g a)) Has there been a change to "deriving"? Is there a workaround? Thanks, - Conal