Provided by: ocaml-man_4.08.1-8_all 
NAME
Seq - Functional Iterators
Module
Module Seq
Documentation
Module Seq
: sig end
Functional Iterators
The type 'a t is a delayed list, i.e. a list where some evaluation is needed to access the next element.
This makes it possible to build infinite sequences, to build sequences as we traverse them, and to
transform them in a lazy fashion rather than upfront.
type 'a t = unit -> 'a node
The type of delayed lists containing elements of type 'a . Note that the concrete list node 'a node is
delayed under a closure, not a lazy block, which means it might be recomputed every time we access it.
type 'a node =
| Nil
| Cons of 'a * 'a t
(* A fully-evaluated list node, either empty or containing an element and a delayed tail.
*)
val empty : 'a t
The empty sequence, containing no elements.
val return : 'a -> 'a t
The singleton sequence containing only the given element.
val map : ('a -> 'b) -> 'a t -> 'b t
map f seq returns a new sequence whose elements are the elements of seq , transformed by f . This
transformation is lazy, it only applies when the result is traversed.
If seq = [1;2;3] , then map f seq = [f 1; f 2; f 3] .
val filter : ('a -> bool) -> 'a t -> 'a t
Remove from the sequence the elements that do not satisfy the given predicate. This transformation is
lazy, it only applies when the result is traversed.
val filter_map : ('a -> 'b option) -> 'a t -> 'b t
Apply the function to every element; if f x = None then x is dropped; if f x = Some y then y is returned.
This transformation is lazy, it only applies when the result is traversed.
val flat_map : ('a -> 'b t) -> 'a t -> 'b t
Map each element to a subsequence, then return each element of this sub-sequence in turn. This
transformation is lazy, it only applies when the result is traversed.
val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a
Traverse the sequence from left to right, combining each element with the accumulator using the given
function. The traversal happens immediately and will not terminate on infinite sequences.
Also see List.fold_left
val iter : ('a -> unit) -> 'a t -> unit
Iterate on the sequence, calling the (imperative) function on every element. The traversal happens
immediately and will not terminate on infinite sequences.