From ae886c2f0890b40110472d43fb10ef377dee8018 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Sun, 24 Jan 2021 11:18:53 -0500
Subject: [PATCH] add `CCList.chunks`

---
 src/core/CCList.ml        | 11 +++++++++++
 src/core/CCList.mli       |  7 +++++++
 src/core/CCListLabels.mli |  7 +++++++
 3 files changed, 25 insertions(+)

diff --git a/src/core/CCList.ml b/src/core/CCList.ml
index 21f2569f..0aef95d4 100644
--- a/src/core/CCList.ml
+++ b/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
     | [] -> []
diff --git a/src/core/CCList.mli b/src/core/CCList.mli
index 54c6cda0..ae933c88 100644
--- a/src/core/CCList.mli
+++ b/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
diff --git a/src/core/CCListLabels.mli b/src/core/CCListLabels.mli
index 1fa40a1d..8b5b87ca 100644
--- a/src/core/CCListLabels.mli
+++ b/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