/**
 * First-in, first-out (FIFO) buffer (queue) with default item values.
 */
export default class Queue<A> extends Array<A> {
    /**
     * Add an item to the end of the queue.
     *
     * @param a Item to be enqueued
     */
    enqueue(a: A): void;
    /**
     * Either handles and returns the first item in the queue (if the queue isn't empty) or
     * makes and returns a default value.
     *
     * @param handle Callback for handling the first item in the queue
     * @param init Callback for making the default value
     */
    dequeueDefault<B>(handle: (a: A) => B, init: () => B): B;
}