Added [Atom.Set.union_many].

src/Atom.ml

@@ -144,6 +144,13 @@ module Set = struct
   let disjoint xs ys =
     is_empty (inter xs ys)
 
+  (* Iterated union. *)
+
+  let union_many (f : 'a -> t) (xs : 'a list) : t =
+    List.fold_left (fun accu x ->
+      union accu (f x)
+      ) empty xs
+
   (* Disjoint union. *)
 
   exception NonDisjointUnion of atom

src/Atom.mli

@@ -30,6 +30,8 @@ module Set : sig
 
   val disjoint: t -> t -> bool
 
+  val union_many: ('a -> t) -> 'a list -> t
+
   (* Disjoint union. *)
 
   exception NonDisjointUnion of atom