add CCSet.to_string

src/core/CCSet.ml

@@ -8,6 +8,13 @@ type 'a printer = Format.formatter -> 'a -> unit
 
 module type OrderedType = Set.OrderedType
 
+(*$inject
+  module S = CCSet.Make(struct
+    type t = int
+    let compare x y = Stdlib.compare x y
+  end)
+*)
+
 module type S = sig
   include Set.S
 
@@ -59,6 +66,12 @@ module type S = sig
 
   val to_list : t -> elt list
 
+  val to_string :
+    ?start:string -> ?stop:string -> ?sep:string ->
+    (elt -> string) -> t -> string
+  (**  Print the set in a string
+       @since NEXT_RELEASE *)
+
   val pp :
     ?start:string -> ?stop:string -> ?sep:string ->
     elt printer -> t printer
@@ -135,6 +148,26 @@ module Make(O : Map.OrderedType) = struct
 
   let to_list = elements
 
+  let to_string ?(start="") ?(stop="") ?(sep=",") elt_to_string h =
+    to_list h
+    |> CCList.to_string ~start ~stop ~sep elt_to_string
+
+  (*$= & ~printer:(fun s -> s)
+    (S.to_string string_of_int (S.of_list [4; 3])) "3,4"
+  *)
+  (*$Q
+    Q.(list int) (fun l -> \
+      let s = S.of_list l in \
+      (S.to_string string_of_int s) \
+        = (CCList.sort_uniq ~cmp:CCInt.compare l \
+           |> List.map string_of_int |> String.concat ","))
+    Q.(list int) (fun l -> \
+      let s = S.of_list l in \
+      (S.to_string ~sep:" " string_of_int s) \
+        = (CCList.sort_uniq ~cmp:CCInt.compare l \
+           |> List.map string_of_int |> String.concat " "))
+  *)
+
   let pp ?(start="") ?(stop="") ?(sep=", ") pp_x fmt m =
     Format.pp_print_string fmt start;
     let first = ref true in

src/core/CCSet.mli

@@ -65,6 +65,12 @@ module type S = sig
   val to_list : t -> elt list
   (** [to_list t] converts the set [t] to a list of the elements. *)
 
+  val to_string :
+    ?start:string -> ?stop:string -> ?sep:string ->
+    (elt -> string) -> t -> string
+  (**  Print the set in a string
+       @since NEXT_RELEASE *)
+
   val pp :
     ?start:string -> ?stop:string -> ?sep:string ->
     elt printer -> t printer