Module Lwt_sequence

module Lwt_sequence: sig..end

Mutable sequence of elements



A sequence is an object holding a list of elements which support the following operations:

  • adding an element to the left or the right in time and space O(1)
  • taking an element from the left or the right in time and space O(1)
  • removing a previously added element from a sequence in time and space O(1)
  • removing an element while the sequence is being transversed.


type 'a t

Type of a sequence holding values of type 'a

type 'a node

Type of a node holding one value of type 'a in a sequence


Operation on nodes


val get : 'a node -> 'a

Returns the contents of a node

val set : 'a node -> 'a -> unit

Change the contents of a node

val remove : 'a node -> unit

Removes a node from the sequence it is part of. It does nothing if the node has already been removed.


Operations on sequence


val create : unit -> 'a t

create () creates a new empty sequence

val is_empty : 'a t -> bool

Returns true iff the given sequence is empty

val add_l : 'a -> 'a t -> 'a node

add_l x s adds x to the left of the sequence s

val add_r : 'a -> 'a t -> 'a node

add_l x s adds x to the right of the sequence s

exception Empty

Exception raised by take_l and tale_s and when the sequence is empty

val take_l : 'a t -> 'a

take_l x s remove and returns the leftmost element of s
Raises Empty if the sequence is empty

val take_r : 'a t -> 'a

take_l x s remove and returns the rightmost element of s
Raises Empty if the sequence is empty

val take_opt_l : 'a t -> 'a option

take_opt_l x s remove and returns Some x where x is the leftmost element of s or None if s is empty

val take_opt_r : 'a t -> 'a option

take_opt_l x s remove and returns Some x where x is the rightmost element of s or None if s is empty

val transfer_l : 'a t -> 'a t -> unit

transfer_l s1 s2 removes all elements of s1 and add them at the left of s2. This operation runs in constant time and space.

val transfer_r : 'a t -> 'a t -> unit

transfer_r s1 s2 removes all elements of s1 and add them at the right of s2. This operation runs in constant time and space.


Sequence iterators



Note: it is OK to remove a node while traversing a sequence

val iter_l : ('a -> unit) -> 'a t -> unit

iter_l f s applies f on all elements of s starting from the left

val iter_r : ('a -> unit) -> 'a t -> unit

iter_l f s applies f on all elements of s starting from the right

val iter_node_l : ('a node -> unit) -> 'a t -> unit

iter_l f s applies f on all nodes of s starting from the left

val iter_node_r : ('a node -> unit) -> 'a t -> unit

iter_l f s applies f on all nodes of s starting from the right

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

fold_l f s is:

        fold_l f s x = f en (... (f e2 (f e1 x)))
      

where e1, e2, ..., en are the elements of s

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

fold_r f s is:

        fold_r f s x = f e1 (f e2 (... (f en x)))
      

where e1, e2, ..., en are the elements of s