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feat: add CCList.take_last

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Ratakor 2025-12-16 21:39:25 +01:00
parent c1b13f1c7f
commit fafb8aa0a8
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4 changed files with 33 additions and 0 deletions
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14
src/core/CCList.ml
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@ -823,6 +823,20 @@ let hd_tl = function
let take_drop n l = take n l, drop n l
let rec take_last = function
| [] -> failwith "take_last"
| [ x ] -> [], x
| hd :: tl ->
let tl, lt = take_last tl in
hd :: tl, lt
let rec take_last_opt = function
| [] -> [], None
| [ x ] -> [], Some x
| hd :: tl ->
let tl, lt = take_last_opt tl in
hd :: tl, lt
let sublists_of_len ?(last = fun _ -> None) ?offset n l =
if n < 1 then invalid_arg "sublists_of_len: n must be > 0";
let offset =

6
src/core/CCList.mli
View file

@ -414,6 +414,12 @@ val take_drop_while : ('a -> bool) -> 'a t -> 'a t * 'a t
@since 1.2, but only
@since 2.2 with labels *)
val take_last : 'a t -> 'a t * 'a
(** [take_last l] = (tl l, last l). *)
val take_last_opt : 'a t -> 'a t * 'a option
(** [take_last l] = (tl l, last_opt l). *)
val last : int -> 'a t -> 'a t
(** [last n l] takes the last [n] elements of [l] (or less if
[l] doesn't have that many elements). *)

6
src/core/CCListLabels.mli
View file

@ -447,6 +447,12 @@ val take_drop_while : f:('a -> bool) -> 'a t -> 'a t * 'a t
@since 1.2, but only
@since 2.2 with labels *)
val take_last : 'a t -> 'a t * 'a
(** [take_last l] = (tl l, last l). *)
val take_last_opt : 'a t -> 'a t * 'a option
(** [take_last l] = (tl l, last_opt l). *)
val last : int -> 'a t -> 'a t
(** [last n l] takes the last [n] elements of [l] (or less if
[l] doesn't have that many elements). *)

7
tests/core/t_list.ml
View file

@ -807,6 +807,13 @@ t @@ fun () -> take_while (fun x -> x <> 0) [ 0; 1; 2; 3 ] = [];;
t @@ fun () -> take_while (fun _ -> true) [] = [];;
t @@ fun () -> take_while (fun _ -> true) (1 -- 10) = 1 -- 10;;
t @@ fun () -> take_while (fun _ -> true) (1 -- 300_000) = 1 -- 300_000;;
t @@ fun () -> take_last [ 1 ] = ([], 1);;
t @@ fun () -> take_last [ 1; 2; 3; 4; 5 ] = ([ 1; 2; 3; 4 ], 5);;
t @@ fun () -> take_last (1 -- 10_000) = (1 -- 9_999, 10_000);;
t @@ fun () -> take_last_opt [] = ([], None);;
t @@ fun () -> take_last_opt [ 1 ] = ([], Some 1);;
t @@ fun () -> take_last_opt [ 1; 2; 3; 4; 5 ] = ([ 1; 2; 3; 4 ], Some 5);;
t @@ fun () -> take_last_opt (1 -- 10_000) = (1 -- 9_999, Some 10_000);;
q
Q.(pair (fun1 Observable.int bool) (list small_int))