In article <[EMAIL PROTECTED]>,
Andrew J Bromage <[EMAIL PROTECTED]> wrote:
> This suggests that wrapping each "standard" mathemtaical
> function/operator in its own typeclass would have literally
> no run-time performance penalty:
>
> class Plus a b c | a b -> c where
> (+) :: a -> b -> c
>
> class Mult a b c | a b -> c where
> (*) :: a -> b -> c
As written, this is _not_ a good idea. Trust me, you end up having to
put type annotations everywhere. Even (3 + 4 :: Integer) is ambiguous,
you have to write (3 :: Integer) + (4 :: Integer).
In HBase, I do this:
class Additive a b ab | a b -> ab where
add :: a -> b -> ab;
infixl 6 +;
(+) :: (Additive a a a) => a -> a -> a;
b + a = add a b;
etc.
The arguments are swapped because I read "subtract 1 a" and "a - 1" both
as "subtract 1 from a", etc. Perhaps one could get away with this:
(+) :: (Additive a b a) => a -> b -> a;
--
Ashley Yakeley, Seattle WA
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