Re: [Haskell-cafe] Inheritance and Wrappers

On Mon, 31 Jan 2011, MattMan wrote:

I'm new to Haskell, and am trying to implement some simple typeclasses for doing algebra. For example I have type class (simplified for the sake of argument)

class AbGroup a where add :: a -> a -> a

I would like any type instantiating Num to also be an abelian group:

instance (Num a) => AbGroup a where add i j = i+j,

If all methods of AbGroup can be defined for all Num types - why do you want an AbGroup at all? You could simply write functions with Num constraint. You may be also interested in existing approaches to algebra in Haskell: http://www.haskell.org/haskellwiki/Mathematical_prelude_discussion