src/cycle.js

/**
 * Cycles through the input iterable.
 *
 * @example
 * // returns [0,1,0,1,0,1,0]
 * list(head(cycle(range(2)),7)) ;
 *
 * @param {Iterable} iterable - The input iterable.
 * @returns {IterableIterator}
 *
 */
export default function* cycle(iterable) {
	const buffer = [];

	for (const item of iterable) {
		yield item;
		buffer.push(item);
	}

	if (buffer.length === 0) {
		return;
	}

	while (true) {
		yield* buffer;
	}
}