"Stephanie" == Stephanie Randles <srandles@bigpond.net.au> writes:
Stephanie> Hi, I have a script here Stephanie> interleave :: [Integer] -> [Strings] -> [String] Stephanie> interleave (x:xs) (y:ys) = words [a | a <- (unwords Stephanie> [(show x), (filter (/= 1) y), "+"])] Stephanie> and the error message i receive is Stephanie> (Instance of Num Char required for definition of Stephanie> interleave) the difficult error message is due to the flexibility of the type class system in Haskell. The variable y is of type String, i.e., a list of Char. You try to compare a number (/= 1) with a character (an element of y taken by filter). The number constant 1 imposes the type class Num (for numbers) via the comparison to this character, but you have not made Char an instance of class Num (define +, -, * on Char). Probably that's not what you want; the error message does not address the logical source of error but the point where the constraints mismatched. Good luck -- Christoph Herrmann