Constructive abstract algebra

 This package provides algebraic structures, such as groups, fields,
 rings, modules. It also provides bands, also known as idempotent semigroups
 (band is a semigroup where every element is equal to its own
 square), coalgebras, semirings (rigs), idempotent semirings, also known as
 dioids.
 .
 This package provides a library for the Haskell programming language.
 See http://www.haskell.org/ for more information on Haskell.