Reimport Std.List for splitting list

lib/std/list.ml

@@ -0,0 +1,21 @@
+let split_at n list =
+  if n < 1
+  then [], list
+  else (
+    let rec aux acc n = function
+      | [] -> Stdlib.List.rev acc, []
+      | x :: xs as rest ->
+        if n < 1 then Stdlib.List.rev acc, rest else aux (x :: acc) (pred n) xs
+    in
+    aux [] n list)
+;;
+
+let split_by_size size list =
+  let rec aux acc = function
+    | [] -> Stdlib.List.rev acc
+    | list ->
+      let x, xs = split_at size list in
+      aux (x :: acc) xs
+  in
+  aux [] list
+;;

lib/std/list.mli

@@ -0,0 +1 @@
+val split_by_size : int -> 'a list -> 'a list list

test/std/list_test.ml

@@ -0,0 +1,32 @@
+let pp_list pp ppf list =
+  let pplist =
+    Format.pp_print_list ~pp_sep:(fun ppf () -> Format.fprintf ppf ";") pp
+  in
+  Format.fprintf ppf "[%a]" pplist list
+;;
+
+let dump list = Format.printf "%a" (pp_list (pp_list Format.pp_print_int)) list
+
+let%expect_test "Splitting empty list" =
+  dump @@ Std.List.split_by_size 3 [];
+  [%expect {| [] |}]
+;;
+
+let%expect_test "Splitting list - 1" =
+  dump @@ Std.List.split_by_size 1 [ 1; 2; 3; 4; 5 ];
+  [%expect {| [[1];[2];[3];[4];[5]] |}]
+;;
+
+let%expect_test "Splitting list - 2" =
+  dump
+  @@ Std.List.split_by_size
+       3
+       [ 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15 ];
+  [%expect {| [[1;2;3];[4;5;6];[7;8;9];[10;11;12];[13;14;15]] |}]
+;;
+
+let%expect_test "Splitting list - 2" =
+  dump
+  @@ Std.List.split_by_size 4 [ 1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 14; 15 ];
+  [%expect {| [[1;2;3;4];[5;6;7;8];[9;10;11;12];[14;15]] |}]
+;;