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Deque

Functions for persistent, double-ended queues.

Deque

type Deque<T> = (List<T>, List<T>)

Double-ended queue

empty

func empty<T>() : Deque<T>

Empty queue

isEmpty

func isEmpty<T>(q : Deque<T>) : Bool

True when the queue is empty

pushFront

func pushFront<T>(q : Deque<T>, x : T) : Deque<T>

Insert a new element on the front end of the queue

peekFront

func peekFront<T>(q : Deque<T>) : ?T

Inspect the (optional) first element on the front end of the queue

popFront

func popFront<T>(q : Deque<T>) : ?(T, Deque<T>)

Remove the first element on the front end of the queue; Returns null when empty.

pushBack

func pushBack<T>(q : Deque<T>, x : T) : Deque<T>

Insert a new element on the back end of the queue

peekBack

func peekBack<T>(q : Deque<T>) : ?T

Inspect the (optional) first element on the back end of the queue

popBack

func popBack<T>(q : Deque<T>) : ?(Deque<T>, T)

Remove the first element on the back end of the queue; Returns null when empty.