semirings-0.1.3.0: two monoids as one, in holy haskimony

In mathematics, a semiring is an algebraic structure consisting of a set together with two binary operations, one commutative and one associative. A semiring has two identity elements respective to its operations. Thus a semiring can be seen as a combination of two monoids, a commutative monoid and an associative monoid. For some useful semirings, see the 'semirings-types' package.