(*
copyright (c) 2013-2014, simon cruanes
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(** {1 Functional Circular List}

Those are infinite lists that are built from a finite list of
elements, and cycles through them.
Unless specified otherwise, operations have an amortized cost in O(1). *)

type +'a t

val singleton : 'a -> 'a t
(** list that cycles on one element *)

val of_list : 'a list -> 'a t
(** build a circular list from a list. Linear in the length
    of the list.
    @raise Invalid_argument if the list is empty *)

val length : 'a t -> int
(** length of the cycle. *)

val cons : 'a -> 'a t -> 'a t
(** [cons x l] adds [x] at the beginning of [l] *)

val snoc : 'a t -> 'a -> 'a t
(** [snoc l x] adds [x] at the end of [l] *)

val next : 'a t -> 'a * 'a t
(** obtain the next element, and the list rotated by one. *)

val rev : 'a t -> 'a t
(** reverse the traversal (goes right-to-left from now). *)

val find : ('a -> bool) -> 'a t -> 'a option
(** [find p l] returns [Some x] where [p x] is [true]
    and [x] belongs to [l], or [None] if no such
    element exists *)

val mem : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool
(** does the element belong to the infinite list? *)

val exists : ('a -> bool) -> 'a t -> bool

val for_all : ('a -> bool) -> 'a t -> bool

val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
(** fold through each element of the list exactly once. *)

(** {2 Iterators} *)

type 'a gen = unit -> 'a option
type 'a sequence = ('a -> unit) -> unit

val gen : 'a t -> 'a gen
(** CCGenerator on elements of the list *)

val seq : 'a t -> 'a sequence
(** CCSequence of elements of the list *)