Refactoring my generalized fizzbuzz to use only applicative higher-order functions

I refactored my my previous version of generalized FizzBuzz, so that, it doesn't use neither for loops nor recursion. Now it only uses: reduce and map.

This is the new code:

	var makeSubstitute = function(substitutionDescriptions) {
	var substituteNumber = (function() {
	var substitutionFns = substitutionDescriptions.map(
	function(desc) {
	return function(number) {
	return desc.pred(number) ? desc.replacement : "";
	};
	}
	);
	return function(number) {
	var res = substitutionFns.reduce(
	function(acc, substite) {
	return acc + substite(number)
	},
	""
	);
	return res !== "" ? res : String(number);
	};
	}());
	return function(numbers) {
	return numbers.map(substituteNumber).join(" ");
	};
	};

view raw fizzBuzzApplicative.js hosted with ❤ by GitHub

The tests are exactly the same as in the previous version:

	describe("FizzBuzz", function () {
	var fizzBuzzSubstitute;
	beforeEach(function () {
	fizzBuzzSubstitute = makeSubstitute([
	{ pred: function(number) {return number % 3 == 0;},
	replacement: "Fizz"},
	{ pred: function(number) {return number % 5 == 0;},
	replacement: "Buzz"}
	]);
	});
	it("works for an empty array", function () {
	expect(fizzBuzzSubstitute([])).toBe("");
	});
	it("returns same number for array with number not multiple of 3 or 5", function () {
	expect(fizzBuzzSubstitute([1])).toBe("1");
	});
	it("returns Fizz for an array with a multiple of 3", function () {
	expect(fizzBuzzSubstitute([3])).toBe("Fizz");
	expect(fizzBuzzSubstitute([9])).toBe("Fizz");
	});
	it("returns Buzz for an array with a multiple of 5", function () {
	expect(fizzBuzzSubstitute([5])).toBe("Buzz");
	expect(fizzBuzzSubstitute([25])).toBe("Buzz");
	});
	it("returns FizzBuzz for an array with a multiple of both 3 and 5", function () {
	expect(fizzBuzzSubstitute([15])).toBe("FizzBuzz");
	});
	it("also works with arrays with more than one element", function () {
	expect(fizzBuzzSubstitute([1, 2, 15])).toBe("1 2 FizzBuzz");
	});
	});
	describe("FizzKozz", function () {
	var fizzKozzSubstitute = makeSubstitute([
	{ pred: function(number) {return number % 3 == 0;},
	replacement: "Fizz"},
	{ pred: function(number) {return number % 2 == 0;},
	replacement: "Kozz"}
	]);
	it("also works with different substitution rules", function () {
	expect(
	fizzKozzSubstitute([1, 2, 4, 6, 15])).toBe("1 Kozz Kozz FizzKozz Fizz");
	});
	});
	describe("FizzOddSeven", function () {
	var fizzOddSevenSubstitute = makeSubstitute([
	{ pred: function(number) {return number % 3 == 0;},
	replacement: "Fizz"},
	{ pred: function(number) {return number % 2 == 1;},
	replacement: "Odd"},
	{ pred: function(number) {return number == 7;},
	replacement: "Seven"}
	]);
	it("works with rules using any predicate on a number", function () {
	expect(
	fizzOddSevenSubstitute(
	[1, 2, 4, 6, 15, 7])).toBe("Odd 2 4 Fizz FizzOdd OddSeven");
	});
	});

view raw substituteFactoryTests.js hosted with ❤ by GitHub