list-tries (hackage): This library provides implementations of finite sets and maps for list keys using tries, both simple and of the Patricia kind. In most (or all? sorry, haven't benchmarked yet) cases, the Patricia tries will have better performance, so use them unless you have reasons not to.  The data types are parametrized over the map type they use internally to store the child nodes: this allows extending them to support different kinds of key types or increasing efficiency. Child maps are required to be instances of the Map class in Data.ListTrie.Base.Map. Some operations additionally require an OrdMap instance.  The Eq, Ord, and Enum modules contain ready structures for key types which are instances of those classes, using lists of pairs, Data.Map, and Data.IntMap respectively.
Keywords: bsd3|data|data-structures|library