The persistent sequence protocol consists of the non-mutating sequence protocol words, such as length and nth, together with the following operations:

The default implementations of the above run in O(n) time; the persistent.vectors vocabulary provides an implementation of these operations in O(1) time.

new-nth ( val i seq -- seq' )

ppush ( val seq -- seq' )

ppop ( seq -- seq' )

The default implementations of the above run in O(n) time; the persistent.vectors vocabulary provides an implementation of these operations in O(1) time.