Re: [Haskell-beginners] Problems defining a type with a multiplication function

Amy,

instance Num Quaternion where

Use this (from Joe's email), and not

instance Num (Quaternion a)

this (from mine). I had skimmed your code too quickly and wrote the above in error because I'd thought you had make Quaternion parametric. Unless you want the parametricity, as in: data Quaternion a = Quaternion a a a a class (Num a) => Num (Quaternion a) where ... Cheers, John