containers
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  1. List Zipper
package containers
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List Zipper

  • since 1.0
type 'a t = 'a list * 'a list

The pair l, r represents the list List.rev_append l r, but with the focus on r

val empty : 'a t

Empty zipper.

val is_empty : _ t -> bool

Empty zipper? Returns true iff the two lists are empty.

val to_list : 'a t -> 'a list

Convert the zipper back to a list. to_list (l,r) is List.rev_append l r.

val to_rev_list : 'a t -> 'a list

Convert the zipper back to a reversed list. In other words, to_list (l,r) is List.rev_append r l.

val make : 'a list -> 'a t

Create a zipper pointing at the first element of the list.

val left : 'a t -> 'a t

Go to the left, or do nothing if the zipper is already at leftmost pos.

val left_exn : 'a t -> 'a t

Go to the left, or

  • raises Invalid_argument

    if the zipper is already at leftmost pos.

val right : 'a t -> 'a t

Go to the right, or do nothing if the zipper is already at rightmost pos.

val right_exn : 'a t -> 'a t

Go to the right, or

  • raises Invalid_argument

    if the zipper is already at rightmost pos.

val modify : ('a option -> 'a option) -> 'a t -> 'a t

Modify the current element, if any, by returning a new element, or returning None if the element is to be deleted.

val insert : 'a -> 'a t -> 'a t

Insert an element at the current position. If an element was focused, insert x l adds x just before it, and focuses on x.

val remove : 'a t -> 'a t

remove l removes the current element, if any.

val is_focused : _ t -> bool

Is the zipper focused on some element? That is, will focused return a Some v?

val focused : 'a t -> 'a option

Return the focused element, if any. focused zip = Some _ iff empty zip = false.

val focused_exn : 'a t -> 'a

Return the focused element, or

  • raises Not_found

    if the zipper is at an end.

val drop_before : 'a t -> 'a t

Drop every element on the "left" (calling left then will do nothing).

val drop_after : 'a t -> 'a t

Drop every element on the "right" (calling right then will do nothing), keeping the focused element, if any.

val drop_after_and_focused : 'a t -> 'a t

Drop every element on the "right" (calling right then will do nothing), including the focused element if it is present.