package core_kernel

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package core_kernel
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A simple polymorphic functional queue. Use this data structure for strictly first-in, first-out access to a sequence of values. For a similar data structure with enqueue and dequeue accessors on both ends of a sequence, see Core_kernel.Fdeque.

Amortized running times assume that enqueue/dequeue are used sequentially, threading the changing Fqueue through the calls.

type 'a t
include Bin_prot.Binable.S1 with type 'a t := 'a t
val bin_shape_t : Bin_prot.Shape.t -> Bin_prot.Shape.t
val bin_size_t : ('a, 'a t) Bin_prot.Size.sizer1
val bin_write_t : ('a, 'a t) Bin_prot.Write.writer1
val bin_read_t : ('a, 'a t) Bin_prot.Read.reader1
val __bin_read_t__ : ('a, int -> 'a t) Bin_prot.Read.reader1
val bin_writer_t : ('a, 'a t) Bin_prot.Type_class.S1.writer
val bin_reader_t : ('a, 'a t) Bin_prot.Type_class.S1.reader
val bin_t : ('a, 'a t) Bin_prot.Type_class.S1.t
val compare : ('a -> 'a -> Base.Int.t) -> 'a t -> 'a t -> Base.Int.t
val hash_fold_t : (Base.Hash.state -> 'a -> Base.Hash.state) -> Base.Hash.state -> 'a t -> Base.Hash.state
include Ppx_sexp_conv_lib.Sexpable.S1 with type 'a t := 'a t
val t_of_sexp : (Sexplib0.Sexp.t -> 'a) -> Sexplib0.Sexp.t -> 'a t
val sexp_of_t : ('a -> Sexplib0.Sexp.t) -> 'a t -> Sexplib0.Sexp.t
include Container.S1 with type 'a t := 'a t
val mem : 'a t -> 'a -> equal:('a -> 'a -> bool) -> bool

Checks whether the provided element is there, using equal.

val iter : 'a t -> f:('a -> unit) -> unit
val fold : 'a t -> init:'accum -> f:('accum -> 'a -> 'accum) -> 'accum

fold t ~init ~f returns f (... f (f (f init e1) e2) e3 ...) en, where e1..en are the elements of t

val fold_result : 'a t -> init:'accum -> f:('accum -> 'a -> ('accum, 'e) Base.Result.t) -> ('accum, 'e) Base.Result.t

fold_result t ~init ~f is a short-circuiting version of fold that runs in the Result monad. If f returns an Error _, that value is returned without any additional invocations of f.

val fold_until : 'a t -> init:'accum -> f:('accum -> 'a -> ('accum, 'final) Base__.Container_intf.Continue_or_stop.t) -> finish:('accum -> 'final) -> 'final

fold_until t ~init ~f ~finish is a short-circuiting version of fold. If f returns Stop _ the computation ceases and results in that value. If f returns Continue _, the fold will proceed. If f never returns Stop _, the final result is computed by finish.

Example:

type maybe_negative =
  | Found_negative of int
  | All_nonnegative of { sum : int }

(** [first_neg_or_sum list] returns the first negative number in [list], if any,
    otherwise returns the sum of the list. *)
let first_neg_or_sum =
  List.fold_until ~init:0
    ~f:(fun sum x ->
      if x < 0
      then Stop (Found_negative x)
      else Continue (sum + x))
    ~finish:(fun sum -> All_nonnegative { sum })
;;

let x = first_neg_or_sum [1; 2; 3; 4; 5]
val x : maybe_negative = All_nonnegative {sum = 15}

let y = first_neg_or_sum [1; 2; -3; 4; 5]
val y : maybe_negative = Found_negative -3
val exists : 'a t -> f:('a -> bool) -> bool

Returns true if and only if there exists an element for which the provided function evaluates to true. This is a short-circuiting operation.

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

Returns true if and only if the provided function evaluates to true for all elements. This is a short-circuiting operation.

val count : 'a t -> f:('a -> bool) -> int

Returns the number of elements for which the provided function evaluates to true.

val sum : (module Base__.Container_intf.Summable with type t = 'sum) -> 'a t -> f:('a -> 'sum) -> 'sum

Returns the sum of f i for all i in the container.

val find : 'a t -> f:('a -> bool) -> 'a option

Returns as an option the first element for which f evaluates to true.

val find_map : 'a t -> f:('a -> 'b option) -> 'b option

Returns the first evaluation of f that returns Some, and returns None if there is no such element.

val to_array : 'a t -> 'a array
val min_elt : 'a t -> compare:('a -> 'a -> int) -> 'a option

Returns a minimum (resp maximum) element from the collection using the provided compare function, or None if the collection is empty. In case of a tie, the first element encountered while traversing the collection is returned. The implementation uses fold so it has the same complexity as fold.

val max_elt : 'a t -> compare:('a -> 'a -> int) -> 'a option
include Base.Invariant.S1 with type 'a t := 'a t
val invariant : ('a -> unit) -> 'a t -> unit
include Base.Monad.S with type 'a t := 'a t
val (>>=) : 'a t -> ('a -> 'b t) -> 'b t

t >>= f returns a computation that sequences the computations represented by two monad elements. The resulting computation first does t to yield a value v, and then runs the computation returned by f v.

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

t >>| f is t >>= (fun a -> return (f a)).

module Monad_infix : sig ... end
val bind : 'a t -> f:('a -> 'b t) -> 'b t

bind t ~f = t >>= f

val return : 'a -> 'a t

return v returns the (trivial) computation that returns v.

val map : 'a t -> f:('a -> 'b) -> 'b t

map t ~f is t >>| f.

val join : 'a t t -> 'a t

join t is t >>= (fun t' -> t').

val ignore_m : 'a t -> unit t

ignore_m t is map t ~f:(fun _ -> ()). ignore_m used to be called ignore, but we decided that was a bad name, because it shadowed the widely used Caml.ignore. Some monads still do let ignore = ignore_m for historical reasons.

val all : 'a t list -> 'a list t
val all_unit : unit t list -> unit t

Like all, but ensures that every monadic value in the list produces a unit value, all of which are discarded rather than being collected into a list.

module Let_syntax : sig ... end

These are convenient to have in scope when programming with a monad:

val empty : 'a t

The empty queue.

val enqueue : 'a t -> 'a -> 'a t

enqueue t x returns a queue with adds x to the end of t. Complexity: O(1).

val peek_exn : 'a t -> 'a

Returns the front (least recently enqueued) element. Raises Empty if no element is found. Complexity: O(1).

val top_exn : 'a t -> 'a
  • deprecated [since 2019-11] Use [peek_exn] instead.
val peek : 'a t -> 'a Base.Option.t

Like peek_exn, but returns its result optionally, without exception. Complexity: O(1).

val top : 'a t -> 'a Base.Option.t
  • deprecated [since 2019-11] Use [peek] instead.
val dequeue_exn : 'a t -> 'a * 'a t

dequeue_exn t removes and returns the front of t, raising Empty if t is empty. Complexity: amortized O(1).

val dequeue : 'a t -> ('a * 'a t) Base.Option.t

Like dequeue_exn, but returns result optionally, without exception. Complexity: amortized O(1).

val drop_exn : 'a t -> 'a t

Returns version of queue with front element removed. Complexity: amortized O(1).

val discard_exn : 'a t -> 'a t
  • deprecated [since 2019-11] Use [drop_exn] instead.
val to_list : 'a t -> 'a Base.List.t

to_list t returns a list of the elements in t in order from least-recently-added (at the head) to most-recently-added (at the tail). Complexity: O(n).

val of_list : 'a Base.List.t -> 'a t

of_list is the inverse of to_list. Complexity: O(n).

val to_sequence : 'a t -> 'a Sequence.t

to_sequence returns a Sequence.t of the elements in t in order from from least-recently-added (at the head) to most-recently-added (at the tail). Complexity (if the sequence is fully traversed): O(n).

to_list t = Sequence.to_list (to_sequence t)
val of_sequence : 'a Sequence.t -> 'a t

of_sequence is the inverse of to_sequence. Complexity (if the sequence is fully traversed): O(n).

val length : 'a t -> Base.Int.t

Complexity: O(1).

val is_empty : 'a t -> Base.Bool.t

Complexity: O(1).

val singleton : 'a -> 'a t
module Stable : sig ... end
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