fsharp/fsharpx — pull request #132 by mausch (2012-11-07 23:28:13+00:00)
Title: Monoids

Overhaul of monoids: making them more usable and adding several instances: string, list, any, all, unit, map, set, sum, product; and also operators like dual and tuple.
Introduced semigroup.
Added foldMap for Seq, List, RoseTree.