aLittleJavascriptProblem

fuckzhenghu.js

function *range(x, y) {
    for (let i = x; i <= y; i++)
        yield i;
}

function *map(generator, f) {
    for (let x of generator) {
        yield f(x);
    }
}

function *reverse(generator) {
    let a = generator.next();
    if (a.done === false) {
        yield *reverse(generator);
        yield a.value;
    }
}

const foreach = (generator, f) => {
    for (let x of generator) {
        f(x);
    }
};

// generator is volatile, foreach is not pure
let num = range(1, 10);
num = map(num, (x => x * x));
num = reverse(num);
foreach(num, console.log);%