SOURCE

function mapper(f) {
    return a => map(a, f);
}
const increment = x => x + 1;
const incrementAll = mapper(increment);
console.log('print:',incrementAll([1, 2, 3]));

function map(iterable, f) {
    let iterator = iterable[Symbol.iterator]();
    return {     // This object is both iterator and iterable
        [Symbol.iterator]() { return this; },
        next() {
            let v = iterator.next();
            if (v.done) {
                return v;
            } else {
                return { value: f(v.value) };
            }
        }
    };
}