Perhaps if you search for Abelian Monad or so, you will find interesting things in the category theory literature. Some of them may be transplantable to Haskell --- but you probably don't want a completely commutative structure. Arrows seem to express the dependencies between operations more fine-grained than the sequencing that Monads require. (I meant to look into arrows for ages..)
Matthias. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
