[Haskell-beginners] Problems defining a type with a
multiplication function
John Dorsey
haskell at colquitt.org
Wed Sep 9 17:10:38 EDT 2009
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
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