--Just changed the syntax:
...
--------------------or BETTER just to split classes:
type class HalfBody a = (Num a => (+), (-))
instance HalfBody Vector where
(+) v1 v2 = ...
(-) v1 v2 = ...
...
----- Original Message -----
From: "Marc Ziegert" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Wednesday, January 08, 2003 2:24 PM
Subject: Re: Field labels must be globally unique?
> --------------------It would be nice to be able to overload class-functions like
>classes:
>
> instance (+), (-) -> Vector where
> (+) v1 v2 = ...
> (-) v1 v2 = ...
>
> --------------------instead of overloading parts of a class... (because of
>runtime-errors!)
>
> instance Num Vector where
> (+) v1 v2 = ...
> (-) v1 v2 = ...
> (*) _ _ = undefined
> (/) _ _ = undefined
>
> --------------------or BETTER just to split classes:
>
> class HalfBody a => (Num a =>(+), (-)) where
>
> instance HalfBody Vector where
> (+) v1 v2 = ...
> (-) v1 v2 = ...
>
> --------------------instead of defining new operators...
>
> class HalfBody a where
> (+§) :: a -> a -> a
> (-§) :: a -> a -> a
>
> instance (Num a) => HalfBody a where
> (+§) = (+)
> (-§) = (-)
>
> instance HalfBody Vector where
> (+§) v1 v2 = ...
> (-§) v1 v2 = ...
>
> --------------------------------------------------------------------------------
> > > One is to allow function overloading. This is probably not desirable
> > > because it turns type checking into an NP-hard problem.
>
>
> _______________________________________________
> Haskell mailing list
> [EMAIL PROTECTED]
> http://www.haskell.org/mailman/listinfo/haskell
>
>
_______________________________________________
Haskell mailing list
[EMAIL PROTECTED]
http://www.haskell.org/mailman/listinfo/haskell
