feat: add CCList.cons'

close #354

src/core/CCList.ml

@@ -148,6 +148,12 @@ let (@) = append
   (1-- 10_000) @ (10_001 -- 20_000) = 1 -- 20_000
 *)
 
+let[@inline] cons' l x = x::l
+
+(*$Q
+  Q.(small_list int)(fun l -> List.rev l = List.fold_left cons' [] l)
+  *)
+
 let cons_maybe o l = match o with
   | Some x -> x :: l
   | None -> l

src/core/CCList.mli

@@ -40,6 +40,11 @@ val cons_maybe : 'a option -> 'a t -> 'a t
     [cons_maybe None l] is [l].
     @since 0.13 *)
 
+val cons' : 'a t -> 'a -> 'a t
+(** [cons' l x] is the same as [x :: l]. This is convenient for fold
+    functions such as {!List.fold_left} or {!Array.fold_left}.
+    @since NEXT_RELEASE *)
+
 val (@) : 'a t -> 'a t -> 'a t
 (** [l1 @ l2] is like [append l1 l2].
     Concatenate the two lists [l1] and [l2]. *)

src/core/CCListLabels.mli

@@ -39,6 +39,11 @@ val append : 'a t -> 'a t -> 'a t
 (** [append l1 l2] returns the list that is the concatenation of [l1] and [l2].
     Safe version of {!List.append}. *)
 
+val cons' : 'a t -> 'a -> 'a t
+(** [cons' l x] is the same as [x :: l]. This is convenient for fold
+    functions such as {!List.fold_left} or {!Array.fold_left}.
+    @since NEXT_RELEASE *)
+
 val cons_maybe : 'a option -> 'a t -> 'a t
 (** [cons_maybe (Some x) l] is [x :: l].
     [cons_maybe None l] is [l].