On 9 Apr 2008, at 15:23, Henning Thielemann wrote:
I also recognized that problem in the past, but didn't know how to
solve it. In Haskell 98, methods are resolved using the types of
the operands. How would the compiler find out which implementation
of (+) to choose for an expression like x+y using your approach?
I might describe the idea via mangling. So if one has
class Magma (a; unit, mult) where
unit :: a
mult :: a -> a -> a
then instances
Monoid (a; 0; (+))
Monoid (a; 1; (*))
should logically equivalent to
Monoid_0_+ (a)
0 :: a
(+) :: a -> a -> a
Monoid_1_* (a)
1 :: a
(*) :: a -> a -> a
or whatever internal mangling that ensures that the names Monoid_0_+
and Monoid_1_* are different.
Would this not work? - They code should be essentially a shortcut for
defining new classes.
Hans
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
