On Wed, 9 Apr 2008, Hans Aberg wrote:
Different names result in different operator hierarchies. So a class like class Monoid (a; unit, mult) where unit :: a mult :: a -> a -> a must have an instantiation that specifies the names of the operators. In particular, one will need a class (Monoid (a; 0; (+)), ...) => Num a ... if (+) should be used as Monoid.(+) together with Num.(+).
Or give an example you think may cause problems, and I will give it a try.
I think a classical example are number sequences which can be considered as rings in two ways: 1. elementwise multiplication 2. convolution and you have some function which invokes the ring multiplication f :: Ring a => a -> a and a concrete sequence x :: Sequence Integer what multiplication (elementwise or convolution) shall be used for computing (f x) ?