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package containers
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Functional queues

type 'a sequence = ('a -> unit) -> unit
type 'a klist = unit -> [ `Nil | `Cons of 'a * 'a klist ]
type 'a equal = 'a -> 'a -> bool
type 'a printer = Format.formatter -> 'a -> unit

Basics

type +'a t

Queue containing elements of type 'a

val empty : 'a t
val is_empty : 'a t -> bool
val singleton : 'a -> 'a t
val doubleton : 'a -> 'a -> 'a t
exception Empty
val cons : 'a -> 'a t -> 'a t

Push element at the front of the queue.

val snoc : 'a t -> 'a -> 'a t

Push element at the end of the queue.

val take_front : 'a t -> ('a * 'a t) option

Get and remove the first element.

val take_front_exn : 'a t -> 'a * 'a t

Same as take_front, but fails on empty queues.

  • raises Empty

    if the queue is empty.

val take_front_l : int -> 'a t -> 'a list * 'a t

take_front_l n q takes at most n elements from the front of q, and returns them wrapped in a list.

  • raises Invalid_argument

    if n<0.

val take_front_while : ('a -> bool) -> 'a t -> 'a list * 'a t
val take_back : 'a t -> ('a t * 'a) option

Take last element.

val take_back_exn : 'a t -> 'a t * 'a

Same as take_back, but fails on empty queues.

  • raises Empty

    if the queue is empty.

val take_back_l : int -> 'a t -> 'a t * 'a list

take_back_l n q removes and returns the last n elements of q. The elements are in the order of the queue, that is, the head of the returned list is the first element to appear via take_front. take_back_l 2 (of_list [1;2;3;4]) = of_list [1;2], [3;4].

  • raises Invalid_argument

    if n<0.

val take_back_while : ('a -> bool) -> 'a t -> 'a t * 'a list

Individual extraction

val first : 'a t -> 'a option

First element of the queue.

val last : 'a t -> 'a option

Last element of the queue.

val first_exn : 'a t -> 'a

Same as first but

  • raises Empty

    if the queue is empty.

val last_exn : 'a t -> 'a
val nth : int -> 'a t -> 'a option

Return the i-th element of the queue in logarithmic time.

val nth_exn : int -> 'a t -> 'a

Unsafe version of nth.

  • raises Not_found

    if the index is wrong.

val tail : 'a t -> 'a t

Queue deprived of its first element. Does nothing on empty queues.

val init : 'a t -> 'a t

Queue deprived of its last element. Does nothing on empty queues.

Global Operations

val append : 'a t -> 'a t -> 'a t

Append two queues. Elements from the second one come after elements of the first one. Linear in the size of the second queue.

val rev : 'a t -> 'a t

Reverse the queue, O(n) complexity.

  • since 0.10
val map : ('a -> 'b) -> 'a t -> 'b t

Map values.

val (>|=) : 'a t -> ('a -> 'b) -> 'b t

Synonym to map.

val size : 'a t -> int

Number of elements in the queue (constant time).

val fold : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b
val iter : ('a -> unit) -> 'a t -> unit
val equal : 'a equal -> 'a t equal

Conversions

val of_list : 'a list -> 'a t
val to_list : 'a t -> 'a list
val add_seq_front : 'a sequence -> 'a t -> 'a t
val add_seq_back : 'a t -> 'a sequence -> 'a t
val to_seq : 'a t -> 'a sequence
val of_seq : 'a sequence -> 'a t
val to_klist : 'a t -> 'a klist
val of_klist : 'a klist -> 'a t
val (--) : int -> int -> int t

a -- b is the integer range from a to b, both included.

  • since 0.10
val (--^) : int -> int -> int t

a -- b is the integer range from a to b, where b is excluded.

  • since 0.17
val pp : 'a printer -> 'a t printer
  • since 0.13