OCaml: Set modules

Question

I want to use OCaml to generates sets of data and make comparisons between them. I have seen the documentation for Module types like Set.OrderType, Set.Make

Answer 1

In addition to Chris's answer, it may be useful to say that some standard library modules already adhere to the OrderedType signature. For example, you can simply do:

module StringSet = Set.Make(String) ;;       (* sets of strings *)
module Int64Set = Set.Make(Int64) ;;         (* sets of int64s *)
module StringSetSet = Set.Make(StringSet) ;; (* sets of sets of strings *)

And so on.

Here's a simple usage example for StringSet; remember that sets are functional data structures, so adding a new element to a set returns a new set:

let set = List.fold_right StringSet.add ["foo";"bar";"baz"] StringSet.empty ;;
StringSet.mem "bar" set ;; (* returns true *)
StringSet.mem "zzz" set ;; (* returns false *)