added repeatedly, rand_int, of_array and to_array to Gen

gen.ml

@@ -109,6 +109,11 @@ let repeat x =
   let f () = x in
   fun () -> f
 
+let repeatedly f =
+  fun () ->
+    fun () ->
+      f ()
+
 (** [iterate x f] is [[x; f x; f (f x); f (f (f x)); ...]] *)
 let iterate x f =
   fun () ->
@@ -168,6 +173,14 @@ let scan f acc e =
 let iter f enum =
   Gen.iter f (enum ())
 
+(** Iterate on elements with their index in the enum, from 0 *)
+let iteri f enum =
+  let r = ref 0 in
+  let gen = enum () in
+  try
+    while true do f !r (gen ()); incr r; done
+  with EOG -> ()
+
 let iter2 f e1 e2 =
   let gen1 = e1 () and gen2 = e2 () in
   try
@@ -776,6 +789,27 @@ let of_list l =
 let to_rev_list enum =
   Gen.to_rev_list (enum ())
 
+let to_array enum =
+  let n = length enum in
+  let a = Array.make n (Obj.magic 0) in
+  iteri (fun i x -> a.(i) <- x) enum;
+  a
+
+let of_array ?(start=0) ?len a =
+  let len = match len with
+  | None -> Array.length a
+  | Some n -> assert (n <= Array.length a); n in
+  fun () ->
+    let i = ref start in
+    fun () ->
+      if !i >= len
+        then raise EOG
+        else (let x = a.(!i) in incr i; x)
+
+
+let rand_int i =
+  repeatedly (fun () -> Random.int i)
+
 let int_range i j =
   fun () -> Gen.int_range i j
 

gen.mli

@@ -82,6 +82,10 @@ val singleton : 'a -> 'a t
 val repeat : 'a -> 'a t
   (** Repeat same element endlessly *)
 
+val repeatedly : (unit -> 'a) -> 'a t
+  (** Call the same function an infinite number of times (useful 
+      if the function is a random generator) *)
+
 val iterate : 'a -> ('a -> 'a) -> 'a t
   (** [iterate x f] is [[x; f x; f (f x); f (f (f x)); ...]] *)
 
@@ -109,6 +113,9 @@ val scan : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b t
 val iter : ('a -> unit) -> 'a t -> unit
   (** Iterate on the enum *)
 
+val iteri : (int -> 'a -> unit) -> 'a t -> unit
+  (** Iterate on elements with their index in the enum, from 0 *)
+
 val iter2 : ('a -> 'b -> unit) -> 'a t -> 'b t -> unit
   (** Iterate on the two sequences. Stops once one of them is exhausted.*)
 
@@ -272,6 +279,12 @@ val to_list : 'a t -> 'a list
 val to_rev_list : 'a t -> 'a list
   (** Tail call conversion to list, in reverse order *)
 
+val to_array : 'a t -> 'a array
+
+val of_array : ?start:int -> ?len:int -> 'a array -> 'a t
+
+val rand_int : int -> int t
+
 val int_range : int -> int -> int t
 
 val pp : ?start:string -> ?stop:string -> ?sep:string -> ?horizontal:bool ->