ChurchMath.js

var PLUS = function (n) {
	return function(m) {
		return function(f) {
			return function(z) {
				return n(f)(m(f)(z));
			};
		};
	};
};

var MULT = function (n) {
	return function(m) {
		return function(f) {
			return function(z) {
				return n(m(f))(z);
			};
		};
	};
};

var PRED = function(n) {
	return function(f) {
		return function(z) {
			return (n(function(g) {
				return function(h)  {
					return h(g(f));
				}}) (function(u) {return z;}))
				(function(u) {return u;});
		};
	};
};

var SUB = function(m){
	return function(n) {
		return m(PRED)(n);
	}
}

function createChurchNumeral(n) {
	f = ZERO
	// apply SUCC repeatedly to ZERO n times
	for (var i=0; i<n; i++)
		f = SUCC(f);
	return f; // f is function
};

// example
console.log(numerify(createChurchNumeral(5))); // should print 5
console.log(numerify(SUCC(ZERO))); // should print 1

// FOUR is that function which applies incr 4 times to 0
FOUR = createChurchNumeral(4);
SIX = createChurchNumeral(6); 

console.log(numerify(PLUS(FOUR)(SIX))); // prints 10
console.log(numerify(PRED(creatChurchNumeral(2)))); // prints 1
console.log(numerify(PRED(ZERO))); // prints 0
console.log(numerify(SUB(FOUR)(SIX))); // print 0
console.log(numerify(MULT(FOUR)(SIX))); // print 24