Module `Appendable_list`

A polymorphic data structure parametrized by 'a to represent lists of elements of 'a while supporting constant time append operations.

One example of use is to manipulate a decorated text represented as a sequence of words. Eventually we are interested in producing the concatenation of all the word in some form, but we do not want to pay the allocation costs of buildings intermediate string concatenations.

This module is a generalization of the Rope module. Essentially: type Rope.t = string Appendable_list.t

The following operations all run in constant time: empty, of_list, singleton, append, concat, add_front, add_back

to_sequence builds a sequence where access to the next element has an amortized constant time.

All traversal operations such as iter and fold are tail recursive.

The monad exported by the module is semantically the same as the one in List. That is: bind t f applies f to each element of t and append the resulting list respecting the order in which the elements appear in t.

type +'a t

include Ppx_sexp_conv_lib.Sexpable.S1 with type +'a t := 'a t

type '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

val empty : _ t
val of_list : 'a list -> 'a t
val singleton : 'a -> 'a t
val append : 'a t -> 'a t -> 'a t
val concat : 'a t list -> 'a t
val add_front : 'a -> 'a t -> 'a t
val add_back : 'a t -> 'a -> 'a t
val to_sequence : 'a t -> 'a Core_kernel.Sequence.t

include Core_kernel.Monad.S with type 'a t := 'a t

type 'a t

include Base__.Monad_intf.S_without_syntax with type 'a t := 'a t

type 'a t

include Base__.Monad_intf.Infix with type 'a t := 'a t

type '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 : Base__.Monad_intf.Infix with type 'a t := 'a t

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.

include Base__.Monad_intf.Syntax with type 'a t := 'a t

type 'a t

module Let_syntax : sig ... end

include Core_kernel.Container.S1 with type 'a t := 'a t

type 'a t

val mem : 'a t -> 'a -> equal:('a -> 'a -> bool) -> bool: Checks whether the provided element is there, using equal.

val length : 'a t -> int
val is_empty : 'a t -> bool
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_list : 'a t -> 'a list
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

module For_testing : sig ... end