# unions

The union of a list of maps. > unions [(fromList [(5, "a"), (3, "b")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "A3"), (3, "B3")])] > == fromList [(3, "b"), (5, "a"), (7, "C")] > unions [(fromList [(5, "A3"), (3, "B3")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "a"), (3, "b")])] > == fromList [(3, "B3"), (5, "A3"), (7, "C")]
The union of a list of sets.
The union of a list of sets: (unions == foldl union empty).
The union of a list of maps: (unions == foldl union empty). > unions [(fromList [(5, "a"), (3, "b")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "A3"), (3, "B3")])] > == fromList [(3, "b"), (5, "a"), (7, "C")] > unions [(fromList [(5, "A3"), (3, "B3")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "a"), (3, "b")])] > == fromList [(3, "B3"), (5, "A3"), (7, "C")]
The union of a list of maps, with a combining operation. > unionsWith (++) [(fromList [(5, "a"), (3, "b")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "A3"), (3, "B3")])] > == fromList [(3, "bB3"), (5, "aAA3"), (7, "C")]
The union of a list of maps, with a combining operation: (unionsWith f == foldl (unionWith f) empty). > unionsWith (++) [(fromList [(5, "a"), (3, "b")]), (fromList [(5, "A"), (7, "C")]), (fromList [(5, "A3"), (3, "B3")])] > == fromList [(3, "bB3"), (5, "aAA3"), (7, "C")]