http://hackage.haskell.org/cgi-bin/hackage-scripts/package/gmap-0.1 Everything in the release is working. There's some fast map/trie implementations and a bunch of map combinators. In Test.GMap there are ~800 lines of quickcheck properties. The tests use some undocumented type hackery to allow them to run on any instance of the GMap class. Some of the strictness invariants demanded by the test suite are not documented. There are no real benchmarks. I'm still not even sure how to effectively benchmark haskell code. If you want to suggest this as a project for 2009 I think the priorities should be: Documentation + examples (which I'm willing to help with if there is interest) Systematic benchmarks Integration with the edison api, to encourage a single collection api on hackage Jamie