michael@0: // Church-Peano integers
michael@0: 
michael@0: var Zero = f => x => x;
michael@0: var Succ = n => f => x => n(f)(f(x));
michael@0: var Add = a => b => f => x => a(f)(b(f)(x));
michael@0: var Mul = a => b => f => x => a(b(f))(x);
michael@0: var Exp = a => b => b(a);
michael@0: 
michael@0: var n = f => f(k => k + 1)(0);
michael@0: 
michael@0: assertEq(n(Zero), 0);
michael@0: assertEq(n(Succ(Zero)), 1);
michael@0: assertEq(n(Succ(Succ(Zero))), 2);
michael@0: 
michael@0: var Three = Succ(Succ(Succ(Zero)));
michael@0: var Five = Succ(Succ(Three));
michael@0: assertEq(n(Add(Three)(Five)), 8);
michael@0: assertEq(n(Mul(Three)(Five)), 15);
michael@0: assertEq(n(Exp(Three)(Five)), 243);