nondeterminism-shift-reset.js

function choose(args) {
    return shift(function(k) {
        let results = [ ];
        for (let i = 0; i < args.length; i++) {
            results = results.concat(k(args[i]));
        }
        return results;
    });
}

function fail() {
    return shift(function(k) {
        return [];
    });
}

function driver(body) {
    return reset(function() {
        return [body()];
    });
}

function F() {
    return choose([1,2,3]);
}

results = driver(function() {
    let x = F();
    let y = F();
    if ((x + y) % 2 !== 0) {
        fail();
    }
    return x + y;
});