union -unix -containers

union :: Eq a => [a] -> [a] -> [a]
base Data.List
The union function returns the list union of the two lists. For example, > "dog" `union` "cow" == "dogcw" Duplicates, and elements of the first list, are removed from the the second list, but if the first list contains duplicates, so will the result. It is a special case of unionBy, which allows the programmer to supply their own equality test.
unionBy :: (a -> a -> Bool) -> [a] -> [a] -> [a]
base Data.List
The unionBy function is the non-overloaded version of union.
package union-find
package
The Union/Find algorithm implements these operations in (effectively) constant-time: * Check whether two elements are in the same equivalence class. * Create a union of two equivalence classes. * Look up the descriptor of the equivalence class. Version 0.2
package union-find-array
package
ST based implementation of Tarjan's disjoint set forests, using mutable arrays storing indices instead of references internally. There is also a pure, immutable version of the data structure, which is useful for querying the result of a union find construction. Version 0.1
package funion
package
A unioning file-system using HFuse Version 0.0.2