feat(CCSeq): add some missing function from 4.14

src/core/CCSeq.ml

@@ -21,6 +21,13 @@ let nil () = Nil
 let cons a b () = Cons (a, b)
 let empty = nil
 let singleton x () = Cons (x, nil)
+
+let init n f =
+  let rec aux i () =
+    if i >= n then Nil else Cons (f i, aux (i+1))
+  in
+  aux 0
+
 let rec _forever x () = Cons (x, _forever x)
 
 let rec _repeat n x () =
@@ -34,6 +41,8 @@ let repeat ?n x =
   | None -> _forever x
   | Some n -> _repeat n x
 
+let rec forever f () = Cons (f (), forever f)
+
 let is_empty l =
   match l () with
   | Nil -> true
@@ -59,6 +68,11 @@ let tail l =
   | Nil -> None
   | Cons (_, l) -> Some l
 
+let uncons l =
+  match l () with
+  | Nil -> None
+  | Cons (h, t) -> Some (h, t)
+
 let rec equal eq l1 l2 =
   match l1 (), l2 () with
   | Nil, Nil -> true
@@ -84,6 +98,16 @@ let rec fold f acc res =
 
 let fold_left = fold
 
+let foldi f acc res =
+  let rec aux acc i res =
+    match res () with
+      | Nil -> acc
+      | Cons (s, cont) -> aux (f acc i s) (i+1) cont
+  in
+  aux acc 0 res
+
+let fold_lefti = foldi
+
 let rec iter f l =
   match l () with
   | Nil -> ()
@@ -170,6 +194,8 @@ let rec append l1 l2 () =
 
 let rec cycle l () = append l (cycle l) ()
 
+let rec iterate f a () = Cons (a, iterate f (f a))
+
 let rec unfold f acc () =
   match f acc with
   | None -> Nil
@@ -185,6 +211,26 @@ let rec exists p l =
   | Nil -> false
   | Cons (x, tl) -> p x || exists p tl
 
+let rec find p l =
+  match l () with
+    | Nil -> None
+    | Cons (x, tl) ->
+      if p x then Some x else find p tl
+
+let rec find_map f l =
+  match l () with
+    | Nil -> None
+    | Cons (x, tl) ->
+      match f x with
+        | None -> find_map f tl
+        | e -> e
+
+let rec scan f acc res () = Cons (acc, fun () ->
+  match res () with
+  | Nil -> Nil
+  | Cons (s, cont) -> scan f (f acc s) cont ())
+
+
 let rec flat_map f l () =
   match l () with
   | Nil -> Nil
@@ -195,6 +241,8 @@ and _flat_map_app f l l' () =
   | Nil -> flat_map f l' ()
   | Cons (x, tl) -> Cons (x, _flat_map_app f tl l')
 
+let concat = flat_map
+
 let product_with f l1 l2 =
   let rec _next_left h1 tl1 h2 tl2 () =
     match tl1 () with
@@ -218,6 +266,8 @@ let product_with f l1 l2 =
   in
   _next_left [] l1 [] l2
 
+let map_product = product_with
+
 let product l1 l2 = product_with (fun x y -> x, y) l1 l2
 
 let rec group eq l () =
@@ -248,6 +298,8 @@ let rec filter_map f l () =
 
 let flatten l = flat_map (fun x -> x) l
 
+let concat = flatten
+
 let range i j =
   let rec aux i j () =
     if i = j then
@@ -274,6 +326,8 @@ let rec fold2 f acc l1 l2 =
   | Nil, _ | _, Nil -> acc
   | Cons (x1, l1'), Cons (x2, l2') -> fold2 f (f acc x1 x2) l1' l2'
 
+let fold_left2 = fold2
+
 let rec map2 f l1 l2 () =
   match l1 (), l2 () with
   | Nil, _ | _, Nil -> Nil
@@ -306,6 +360,8 @@ let rec merge cmp l1 l2 () =
     else
       Cons (x2, merge cmp l1 l2')
 
+let sorted_merge = merge
+
 let rec zip a b () =
   match a (), b () with
   | Nil, _ | _, Nil -> Nil
@@ -323,6 +379,8 @@ let unzip l =
   in
   first l, second l
 
+let split = unzip
+
 let zip_i seq =
   let rec loop i seq () =
     match seq () with

src/core/CCSeq.mli

@@ -29,19 +29,34 @@ val empty : 'a t
 val cons : 'a -> 'a t -> 'a t
 val singleton : 'a -> 'a t
 
+val init : int -> (int -> 'a) -> 'a t
+(** [init n f] corresponds to the sequence [f 0; f 1; ...; f (n-1)].
+    @raise Invalid_argument if n is negative.
+    @since NEXT_RELEASE *)
+
 val repeat : ?n:int -> 'a -> 'a t
 (** [repeat ~n x] repeats [x] [n] times then stops. If [n] is omitted,
     then [x] is repeated forever. *)
 
+val forever : (unit -> 'a) -> 'a t
+(** [forever f] corresponds to the infinit sequence containing all the [f ()].
+    @since NEXT_RELEASE *)
+
 val cycle : 'a t -> 'a t
 (** Cycle through the iterator infinitely. The iterator shouldn't be empty. *)
 
+val iterate : ('a -> 'a) -> 'a -> 'a t
+(** [iterate f a] corresponds to the infinit sequence containing [a], [f a], [f (f a)],
+    ...]
+    @since NEXT_RELEASE *)
+
 val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a t
 (** [unfold f acc] calls [f acc] and:
     - if [f acc = Some (x, acc')], yield [x], continue with [unfold f acc'].
     - if [f acc = None], stops. *)
 
 val is_empty : 'a t -> bool
+(** [is_empty xs] checks in the sequence [xs] is empty *)
 
 val head : 'a t -> 'a option
 (** Head of the list. *)
@@ -57,6 +72,10 @@ val tail_exn : 'a t -> 'a t
 (** Unsafe version of {!tail}.
     @raise Not_found if the list is empty. *)
 
+val uncons : 'a t -> ('a * 'a t) option
+(** [uncons xs] return [None] if [xs] is empty other
+    @since NEXT_RELEASE *)
+
 val equal : 'a equal -> 'a t equal
 (** Equality step by step. Eager. *)
 
@@ -69,6 +88,16 @@ val fold : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
 val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
 (** Alias for {!fold} *)
 
+val foldi : ('a -> int -> 'b -> 'a) -> 'a -> 'b t -> 'a
+(** [fold_lefti f init xs] applies [f acc i x] where [acc] is the result of the previous
+    computation or [init] for the first one, [i] is the index in the sequence (starts at
+    0) and [x] is the element of the sequence.
+    @since NEXT_RELEASE *)
+
+val fold_lefti : ('a -> int -> 'b -> 'a) -> 'a -> 'b t -> 'a
+(** Alias of {!foldi}.
+    @since NEXT_RELEASE *)
+
 val iter : ('a -> unit) -> 'a t -> unit
 
 val iteri : (int -> 'a -> unit) -> 'a t -> unit
@@ -96,6 +125,10 @@ val product_with : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
 (** Fair product of two (possibly infinite) lists into a new list. Lazy.
     The first parameter is used to combine each pair of elements. *)
 
+val map_product : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
+(** Alias of {!product_with}.
+    @since NEXT_RELEASE *)
+
 val product : 'a t -> 'b t -> ('a * 'b) t
 (** Specialization of {!product_with} producing tuples. *)
 
@@ -123,9 +156,33 @@ val exists : ('a -> bool) -> 'a t -> bool
     sequence until it finds an element satisfying the predicate.
     @since 3.3 *)
 
+val find : ('a -> bool) -> 'a t -> 'a option
+(** [find p [a1; ...; an]] return [Some ai] for the first [ai] satisfying the predicate
+    [p] and return [None] otherwise.
+    @since NEXT_RELEASE *)
+
+val find_map : ('a -> 'b option) -> 'a t -> 'b option
+(** [find f [a1; ...; an]] return [Some (f ai)] for the first [ai] such that
+    [f ai = Some _] and return [None] otherwise.
+    @since NEXT_RELEASE *)
+
+val scan : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a t
+(** [scan f init xs] is the sequence containing the intermediate result of
+    [fold f init xs].
+    @since NEXT_RELEASE *)
+
 val flat_map : ('a -> 'b t) -> 'a t -> 'b t
+val concat_map : ('a -> 'b t) -> 'a t -> 'b t
+(** Aliass of {!flat_map}
+    @since NEXT_RELEASE *)
+
 val filter_map : ('a -> 'b option) -> 'a t -> 'b t
+
 val flatten : 'a t t -> 'a t
+val concat : 'a t t -> 'a t
+(** Alias of {!flatten}.
+    @since NEXT_RELEASE *)
+
 val range : int -> int -> int t
 
 val ( -- ) : int -> int -> int t
@@ -140,6 +197,10 @@ val ( --^ ) : int -> int -> int t
 val fold2 : ('acc -> 'a -> 'b -> 'acc) -> 'acc -> 'a t -> 'b t -> 'acc
 (** Fold on two collections at once. Stop at soon as one of them ends. *)
 
+val fold_left2 : ('acc -> 'a -> 'b -> 'acc) -> 'acc -> 'a t -> 'b t -> 'acc
+(** Alias for {!fold2}.
+    @since NEXT_RELEASE *)
+
 val map2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
 (** Map on two collections at once. Stop as soon as one of the
     arguments is exhausted. *)
@@ -153,12 +214,20 @@ val exists2 : ('a -> 'b -> bool) -> 'a t -> 'b t -> bool
 val merge : 'a ord -> 'a t -> 'a t -> 'a t
 (** Merge two sorted iterators into a sorted iterator. *)
 
+val sorted_merge : 'a ord -> 'a t -> 'a t -> 'a t
+(** Alias of {!merge}.
+    @since NEXT_RELEASE *)
+
 val zip : 'a t -> 'b t -> ('a * 'b) t
 (** Combine elements pairwise. Stop as soon as one of the lists stops. *)
 
 val unzip : ('a * 'b) t -> 'a t * 'b t
 (** Split each tuple in the list. *)
 
+val split : ('a * 'b) t -> 'a t * 'b t
+(** Alias of {!unzip}.
+    @since NEXT_RELEASE *)
+
 val zip_i : 'a t -> (int * 'a) t
 (** [zip_i seq] zips the index of each element with the element itself.
     @since 3.8