functions.js

function assert(description, condition) {
	return `${condition ? '✓' : '×'} ${description}`;
}
function If(bool) {
	return (a) => (b) => bool(a, b);
}

function True(a, b) {
	return a;
}

function False(a, b) {
	return b;
}

console.log('\nstart testing If...');
console.log(assert('should return 1 when true', If(True)(1)(2) === 1));
console.log(assert('should return 2 when false', If(False)(1)(2) === 2));
console.log('end testing If\n');

function And(a) {
	return (b) => If(a)(If(b)(True)(False))(False);
}

console.log('\nstart testing And...');
console.log(assert('1 && 1 === 1', And(True)(True) === True));
console.log(assert('1 && 0 === 0', And(True)(False) === False));
console.log(assert('0 && 1 === 0', And(False)(True) === False));
console.log(assert('0 && 0 === 0', And(False)(False) === False));
console.log('end testing And\n');

function Or(a) {
	return (b) => If(a)(True)(If(b)(True)(False));
}

console.log('\nstart testing Or...');
console.log(assert('1 || 1 === 1', Or(True)(True) === True));
console.log(assert('1 || 0 === 1', Or(True)(False) === True));
console.log(assert('0 || 1 === 1', Or(False)(True) === True));
console.log(assert('0 || 0 === 0', Or(False)(False) === False));
console.log('end testing Or\n');

function Not(bool) {
	return If(bool)(False)(True);
}

console.log('\nstart testing Not...');
console.log(assert('!True === False', Not(True) === False));
console.log(assert('!False === True', Not(False) === True));
console.log('end testing Not\n');