(*
Copyright (c) 2013, Simon Cruanes
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*)

(** {1 Consumable generators} *)

(** This structure is inspired from Ocaml Batteries' BatEnum.t. It features
    restartable generators. *)

exception EOG
  (** End of Generation *)

type 'a t = unit -> 'a generator
  (** An enum is a generator of generators *)
and 'a generator = unit -> 'a
  (** A generator may be called several times, yielding the next value
      each time. It raises EOG when it reaches the end. *)

val empty : 'a t
  (** Enmpty enum *)

val singleton : 'a -> 'a t
  (** One-element enum *)

val start : 'a t -> 'a generator
  (** Create a new generator *)

val next : 'a generator -> 'a
  (** Get next element, or raise EOG *)

val junk : 'a generator -> unit
  (** Drop element *)

val is_empty : _ t -> bool
  (** Check whether the enum is empty *)

val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
  (** Fold on the generator *)

val iter : ('a -> unit) -> 'a t -> unit
  (** Iterate on the enum *)

val length : _ t -> int
  (** Length of an enum (linear time) *)

val map : ('a -> 'b) -> 'a t -> 'b t
  (** Lazy map *)

val append : 'a t -> 'a t -> 'a t
  (** Append the two enums *)

val flatten : 'a t t -> 'a t
  (** Flatten the enum of enum *)

val flatMap : ('a -> 'b t) -> 'a t -> 'b t
  (** Monadic bind *)

val take : int -> 'a t -> 'a t
  (** Take at most n elements *)

val drop : int -> 'a t -> 'a t
  (** Drop n elements *)

val of_list : 'a list -> 'a t
  (** Enumerate the list *)

val to_list : 'a t -> 'a list
  (** non tail-call trasnformation to list *)

val to_rev_list : 'a t -> 'a list
  (** Tail call conversion to list, in reverse order *)

val int_range : int -> int -> int t

module Infix : sig
  val (@@) : 'a t -> 'a t -> 'a t
  val (>>=) : 'a t -> ('a -> 'b t) -> 'b t
  val (--) : int -> int -> int t
end