static dynamic apply_io(Lambda f) {
    Lambda i() {
        bool collected = false;
        Lambda next_fun = null;
        uint input = 0;

        return (Lazy callback) => {
            if(!collected) {
                input = (uint) Console.Read();
                next_fun = i();
                collected = true;
            }

            var next_fun_applicable = (Lambda) callback();
            var char_applicable = (Lambda) next_fun_applicable(lazy(() => next_fun));
            return char_applicable(lazy(() => to_church_natural(input)));
        };
    }

    Lambda o() {
        bool written = false;
        Lambda next_fun = null;

        return (Lazy m) => {
            if(written) {
                return next_fun;
            }

            written = true;
            Console.Write((char) from_church_natural((Lambda) m()));
            next_fun = o();
            return next_fun;
        };
    }

    var ifun = i();
    var ofun = o();
    return ((Lambda) f(lazy(() => ifun)))(lazy(() => ofun));
}