On 2 Apr 2008, at 16:20, Loup Vaillant wrote:
class AdditiveSemiMonoid a where
(+) :: a -> a -> a
Err, why *semi* monoid? Plain "monoid" would not be accurate?
A monoid has a unit:
class (AdditiveSemiMonoid a) => AdditiveMonoid a where
o :: a
The semimonoid is also called semigroup, I think.
<rant>
While we're at it, what about adding even more classes, like "group"
or "ring"? Algebra in a whole class hierachy. :-)
Only ambition required :-).
It is probably easier to make a copy of Prelude.hs to say
NewPrelude.hs, and modify it directly, by inserting intermediate
classes.
Hans
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