1Stdlib.Seq(3)                    OCaml library                   Stdlib.Seq(3)
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NAME

6       Stdlib.Seq - no description
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Module

9       Module   Stdlib.Seq
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Documentation

12       Module Seq
13        : (module Stdlib__seq)
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21       type 'a t = unit -> 'a node
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24       The  type  of delayed lists containing elements of type 'a .  Note that
25       the concrete list node 'a node is delayed under a closure, not  a  lazy
26       block, which means it might be recomputed every time we access it.
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29       type 'a node =
30        | Nil
31        | Cons of 'a * 'a t
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34       A  fully-evaluated list node, either empty or containing an element and
35       a delayed tail.
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39       val empty : 'a t
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41       The empty sequence, containing no elements.
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45       val return : 'a -> 'a t
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47       The singleton sequence containing only the given element.
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51       val cons : 'a -> 'a t -> 'a t
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54       cons x xs is the sequence containing the element x followed by the  se‐
55       quence xs
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59       Since 4.11
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63       val append : 'a t -> 'a t -> 'a t
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66       append xs ys is the sequence xs followed by the sequence ys
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70       Since 4.11
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74       val map : ('a -> 'b) -> 'a t -> 'b t
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77       map f seq returns a new sequence whose elements are the elements of seq
78       , transformed by f .  This transformation is lazy, it only applies when
79       the result is traversed.
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81       If seq = [1;2;3] , then map f seq = [f 1; f 2; f 3] .
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85       val filter : ('a -> bool) -> 'a t -> 'a t
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87       Remove  from  the  sequence  the elements that do not satisfy the given
88       predicate.  This transformation is lazy, it only applies when  the  re‐
89       sult is traversed.
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93       val filter_map : ('a -> 'b option) -> 'a t -> 'b t
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95       Apply  the  function to every element; if f x = None then x is dropped;
96       if f x = Some y then y is returned.  This transformation  is  lazy,  it
97       only applies when the result is traversed.
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101       val flat_map : ('a -> 'b t) -> 'a t -> 'b t
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103       Map  each  element  to  a subsequence, then return each element of this
104       sub-sequence in turn.  This transformation is  lazy,  it  only  applies
105       when the result is traversed.
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109       val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
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111       Traverse  the  sequence from left to right, combining each element with
112       the accumulator using the given function.  The traversal happens  imme‐
113       diately and will not terminate on infinite sequences.
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115       Also see List.fold_left
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120       val iter : ('a -> unit) -> 'a t -> unit
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122       Iterate on the sequence, calling the (imperative) function on every el‐
123       ement.  The traversal happens immediately and will not terminate on in‐
124       finite sequences.
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128       val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a t
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130       Build a sequence from a step function and an initial value.  unfold f u
131       returns empty if f u returns None , or fun () -> Cons (x, unfold  f  y)
132       if f u returns Some (x, y) .
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134       For  example,  unfold  (function  [] -> None | h::t -> Some (h,t)) l is
135       equivalent to List.to_seq l .
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138       Since 4.11
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144OCamldoc                          2021-07-22                     Stdlib.Seq(3)