[Resend with formatting maybe fixed.] Hello I'm trying to define functions that allow you to traverse a bounded enumeration, "wrapping" at the start and the end. My implementation looks like this: next, prev :: (Enum a, Bounded a) => a -> a next = turn 1 prev = turn (-1) turn :: (Enum a, Bounded a) => Int -> a -> a turn n e = toEnum (add (fromEnum (maxBound::a) + 1) (fromEnum e) n) where add mod x y = (x + y + mod) `rem` mod Which fails to type check under GHC with this error: No instance for (Bounded a) arising from use of `maxBound' at Hbot.hs:6:34-41 Probable fix: add (Bounded a) to the expected type of an expression In the expression: maxBound :: a In the first argument of `fromEnum', namely `(maxBound :: a)' In the first argument of `(+)', namely `fromEnum (maxBound :: a)' My (clearly flawed) understanding of the signature I've specified for 'turn' means *exactly* that a is Bounded. Can anyone enlighten me as to where my understanding is going awry and how (whether) I can achieve what I'm trying to do. Thank you Ben