Sequence of elements
A sequence represent a collection of elements, for which you never construct the complete representation.
Basically you should use a sequence when you would prefer using a list or a lazy-list but constructing the whole list explicitly would explode your memory.
All functions returning a sequence operates in time and space O(1).
Note that if you want a ``consumable sequence'', you should prefer using enumerations (from module BatEnum).
type 'a t = unit -> 'a nodeA sequence is a computation which returns a list-like node
include BatInterfaces.Mappable with type 'a mappable = 'a ttype 'a mappable = 'a tThe data structure, e.g. 'a List.t
enum s returns the enumeration of all element of s.
Since enumerations are consumable and sequence are not, it is not possible to have the inverse operations, i.e. of_enum
val length : 'a t -> intReturn the number of elements of the given sequence. This may never return if the sequence is infinite.
val hd : 'a t -> 'aReturns the first element of the sequence or raise Invalid_argument if the sequence is empty.
Returns the sequence without its first elements or raise Invalid_argument if the sequence is empty.
val is_empty : 'a t -> boolis_empty e returns true if e does not contains any element.
val last : 'a t -> 'aReturns the last element of the sequence, or raise Invalid_argument if the sequence is empty.
val at : 'a t -> int -> 'aat l n returns the element at index n (starting from 0) in the sequence l or raise Invalid_argument is the index is outside of l bounds.
append s1 s2 returns the sequence which first returns all elements of s1 then all elements of s2.
concat s returns the sequence which returns all the elements of all the elements of s, in the same order.
val nil : 'a tnil = fun () -> Nil
val empty : 'a tthe empty sequence, containing no elements
val return : 'a -> 'a tthe singleton sequence, containing only the given element
val make : int -> 'a -> 'a tmake n e returns the sequence of length n where all elements are e
val init : int -> (int -> 'a) -> 'a tinit n f returns the sequence returning the results of f 0, f 1.... f (n-1).
val of_list : 'a list -> 'a tConvenience function to build a seq from a list.
val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a tBuild a sequence from a step function and an initial value. unfold f u returns empty if f u returns None, or fun () -> Cons (x, unfold f y) if f u returns Some (x, y).
For example, unfold (function [] -> None | h::t -> Some (h,t)) l is equivalent to List.to_seq l.
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 iter : ('a -> unit) -> 'a t -> unititer f s applies f to all the elements of the sequence. Eager.
val iteri : (int -> 'a -> unit) -> 'a t -> unititeri f s is the same as iter f s, but f is given the index of each element (starting at 0).
iter2 f s1 s2 iterates on elements of s1 and s2 pairwise, and stops when it meets the end of s1 or s2
map f s returns the sequence where elements are elements of s mapped with f. Lazy.
mapi f s lazily maps elements of s into a new sequence, using f. f is also given elements' indexes.
map2 f s1 s2 returns a sequence of elements, resulting from combininig elements of s1 and s2 at the same index using f. The result is as long as the shortest argument.
val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'afold_left f a (cons b0 (... bn)) is f (... (f (f a b0) b1) ...)
bn. Tail-recursive, eager.
val fold_right : ('a -> 'b -> 'b) -> 'a t -> 'b -> 'bfold_right f (cons a0 (cons a1 (cons a2 ...))) b is f a0 (f
a1 (f a2 ...)). Not tail-recursive, eager.
val reduce : ('a -> 'a -> 'a) -> 'a t -> 'areduce f (cons e s) is fold_left f e s.
val max : 'a t -> 'amax s returns the largest value in s as judged by Pervasives.compare
val min : 'a t -> 'amin s returns the smallest value in s as judged by Pervasives.compare
equal ~eq s1 s2 compares elements of s1 and s2 pairwise using eq
Most functions in the following sections have a shortcut semantic similar to the behavior of the usual (&&) and (||) operators : they will force the sequence until they find an satisfying element, and then return immediately.
For example, for_all will only diverge if the sequence begins with an infinite number of true elements --- elements for which the predicate p returns true.
val for_all : ('a -> bool) -> 'a t -> boolfor_all p (cons a0 (cons a1 ...)) checks if all elements of the given sequence satisfy the predicate p. That is, it returns (p a0) && (p a1) && .... Eager, shortcut.
val exists : ('a -> bool) -> 'a t -> boolexists p (cons a0 (cons a1 ...)) checks if at least one element of the sequence satisfies the predicate p. That is, it returns (p a0) || (p a1) || .... Eager, shortcut.
val mem : 'a -> 'a t -> boolmem a l is true if and only if a is equal to an element of l. Eager, shortcut.
val find : ('a -> bool) -> 'a t -> 'a optionfind p s returns the first element of s such as p e returns true, if any. Eager, shortcut.
val find_map : ('a -> 'b option) -> 'a t -> 'b optionfind_map p s finds the first element of s for which p e returns Some r, if any. Eager, short-cut.
filter p s returns the sequence of elements of s satisfying p. Lazy.
Note filter is lazy in that it returns a lazy sequence, but each element in the result is eagerly searched in the input sequence. Therefore, the access to a given element in the result will diverge if it is preceded, in the input sequence, by infinitely many false elements (elements on which the predicate p returns false).
Other functions that may drop an unbound number of elements (filter_map, take_while, etc.) have the same behavior.
filter_map f s returns the sequence of elements filtered and mapped by f. Lazy.
val assoc : 'a -> ('a * 'b) t -> 'b optionassoc a s returns the value associated with key a in the sequence of pairs s. Eager, shortcut.
take n s returns up to the n first elements from sequence s, if available. Lazy.
drop n s returns s without the first n elements, or the empty sequence if s have less than n elements. Lazy.
take_while f s returns the first elements of sequence s which satisfy the predicate f. Lazy.
drop_while f s returns the sequence s with the first elements satisfying the predicate f dropped. Lazy.
Transform a pair of sequences into a sequence of pairs. Lazy.
val print :
?first:string ->
?last:string ->
?sep:string ->
('a BatInnerIO.output -> 'b -> unit) ->
'a BatInnerIO.output ->
'b t ->
unitPrint the contents of a sequence
val to_buffer :
?first:string ->
?last:string ->
?sep:string ->
('a -> string) ->
Buffer.t ->
(unit -> 'a node) ->
unitConvert a sequence to a string in the given buffer; eager.
val to_string :
?first:string ->
?last:string ->
?sep:string ->
('a -> string) ->
'a t ->
stringConvert the sequence to a string; eager.
val of_string :
?first:string ->
?last:string ->
?sep:string ->
(string -> 'a) ->
string ->
'a tCreate a sequence by parsing a string.
module Infix : sig ... endInfix operators matching those provided by BatEnum.Infix
module Exceptionless : sig ... end