add CCList.chunks

src/core/CCList.ml

@@ -922,6 +922,17 @@ let sublists_of_len ?(last=fun _ -> None) ?offset n l =
   [[1;2]; [3;4]] (subs 2 [1;2;3;4;5])
 *)
 
+let chunks n l = sublists_of_len ~last:(fun x -> Some x) n l
+
+(*$Q
+    Q.(small_list small_int) (fun l -> \
+      l = (chunks 3 l |> List.flatten))
+    Q.(small_list small_int) (fun l -> \
+      l = (chunks 5 l |> List.flatten))
+    Q.(small_list small_int) (fun l -> \
+      List.for_all (fun u -> List.length u <= 5) (chunks 5 l))
+*)
+
 let intersperse x l =
   let rec aux_direct i x l = match l with
     | [] -> []

src/core/CCList.mli

@@ -323,6 +323,13 @@ val sublists_of_len :
     @since 1.0, but only
     @since 1.5 with labels *)
 
+val chunks : int -> 'a list -> 'a list list
+(** [chunks n l] returns consecutives chunks of size at most [n] from [l].
+    Each item of [l] will occur in exactly one chunk. Only the last chunk
+    might be of length smaller than [n].
+    Invariant: [(chunks n l |> List.flatten) = l].
+    @since NEXT_RELEASE *)
+
 val intersperse : 'a -> 'a list -> 'a list
 (** [intersperse x l] inserts the element [x] between adjacent elements of the list [l].
     @since 2.1, but only

src/core/CCListLabels.mli

@@ -327,6 +327,13 @@ val sublists_of_len :
     @since 1.0, but only
     @since 1.5 with labels *)
 
+val chunks : int -> 'a list -> 'a list list
+(** [chunks n l] returns consecutives chunks of size at most [n] from [l].
+    Each item of [l] will occur in exactly one chunk. Only the last chunk
+    might be of length smaller than [n].
+    Invariant: [(chunks n l |> List.flatten) = l].
+    @since NEXT_RELEASE *)
+
 val intersperse : x:'a -> 'a list -> 'a list
 (** [intersperse ~x l] inserts the element [x] between adjacent elements of the list [l].
     @since 2.1, but only