lazyMap.js

	// Example: https://repl.it/repls/WhoppingPotableBoards
	function lazyArray(data, func) {
	const out = [];
	for (let i = 0; i < data.length; i++) {
	function set(value) {
	delete out[i];
	return out[i] = value;
	}
	Object.defineProperty(out, i.toString(), {
	configurable: true,
	enumerable: true,
	set, get: () => set(func(data[i])),
	});
	}
	return out;
	}
	/**
	* Will act like an array but when accessing an index for the first time the function will be evaluated.
	*/
	const a = lazyArray([1, 2, 3, 4], x => x * x);