Rewriting Implementations

Is there any Haskell implementations of rewriting tools. This could be any of string, term, equational or whatever forms of rewriting. Also are there any Haskell packages including data structures for algebriac objects like monoids, groups, rings, modules, graphs, categories, enriched categories, K-algebras (ie monoids in K-modules), kan extensions .... Finally, are there any haskell packages for computing quotients of such structures (perhpas using rewriting) Neil