Hello! Can somebody recommend me a good collection library in Haskell? I'm interested in more than one Set implementation, one FiniteMap implementation etc. (we already have this in the standard Haskell'98 library). What I'm searching for is a library where I have the Set, FiniteMap etc. specifications (i.e., typeclasses), and several implementations (i.e., instances) for them. E.g., we can have a list-based implementation of Set (for small sets), but also a tree-based implementation (for larger sets). So, I would like a library with something like this -- sa is a type corresponding to sets of a's -- requires multi-parameter typeclasses class (Eq a) => Set a sa where addSetElem :: sa -> a -> sa -- add an element to a set searchElem :: sa -> a -> Bool -- search an element in a set ... -- list based Set implementation instance (Eq a) => Set a [a] where ... -- ordered-tree Set implementation instance (Ord a) => Set a (OrdTree a) where ... and so on. Furthermore, I'm interested in a library that can be compiled / interpreted by a mainstream tool, e.g., ghc, hugs etc. I've already started writting such a library (mainly for didactic purposes), but I would like to know if an enstablished collection library already exists. Thanks, Alex