Queens ported to yield and generators

code.js

// http://www.javaist.com/blog/2008/11/06/eight-queens-problem-in-prolog/

const EMPTY_LIST = [];

function* between(start, end) {
    for (let v = start; v < end; v++) {
        yield v;
    }
}

function* solution(X, N) {
    if (X > 0) {
        for (const Others of solution(X - 1, N)) {
            for (const Y of between(1, N + 1)) {
                if (noAttack(X, Y, Others)) {
                    yield [[X, Y], Others];
                }
            }
        }
    } else {
        yield EMPTY_LIST;
    }
};

const noAttack = (X, Y, Solution) => {
    if (Solution === EMPTY_LIST) {
        return true;
    } else {
        const [[X1, Y1], Others] = Solution;
        return Y !== Y1 &&
            Y1 - Y !== X1 - X &&
            Y1 - Y !== X - X1 && noAttack(X, Y, Others);
    }
};

const n = 20;
const sol = solution(n, n);
const write = ([[X, Y], Others]) => {
    console.log(X + '/' + Y);
    if (Others !== EMPTY_LIST) {
        write(Others);
    }
};
write(sol.next().value);