[Haskell-cafe] Num instances for 2-dimensional types

[Soenke Hahn]

On Monday 05 October 2009 11:58:28 pm Henning Thielemann wrote:
> On Mon, 5 Oct 2009, Soenke Hahn wrote:
> > On Monday 05 October 2009 10:14:02 pm Henning Thielemann wrote:
> >> I use NumericPrelude that has more fine grained type classes. E.g. (+)
> >> is in Additive and (*) is in Ring.
> >>
> >> http://hackage.haskell.org/package/numeric-prelude
> >
> > That is pretty cool, thanks. How do your import statements look like,
> > when you use numeric-prelude? Mine look a bit ugly:
> >
> > import Prelude hiding ((+), (-), negate)
> > import Algebra.Additive ((+), (-), negate)
> 
> {-# LANGUAGE NoImplicitPrelude #-}
> 
> or
> 
> import Prelude ()
> 
> and
> 
> import qualified Algebra.Additive as Additive   (e.g. for Additive.C)
> import NumericPrelude
> import PreludeBase
> 
> The first form is necessary if you use number literals, what is the case
> for you I think.
> 

Thanks.

If you want to use number literals, you have to implement an instance for 
Algebra.Ring.C, if i understand correctly. Is there any special reason, why 
fromInteger is a method of Algebra.Ring.C?

Sönke