union : ('a list -> 'a list -> 'a list)
- union [1,2,3] [1,5,4,3]; val it = [2,1,5,4,3] : int list - union [1,1,1] [1,2,3,2]; val it = [1,2,3,2] : int list - union [1,2,3,2] [1,1,1] ; val it = [3,2,1,1,1] : int list
High performance set operations may be found in the SML/NJ library.