(() => {

    // knuthShuffle :: [a] -> [a]
    const knuthShuffle = xs =>
        enumFromTo(0, xs.length - 1)
        .reduceRight((a, i) => {
            const
                iRand =  randomRInt(0, i),
                tmp = a[iRand];
            return iRand !== i ? (
                a[iRand] = a[i],
                a[i] = tmp,
                a
            ) : a;
        }, xs);

    const test = () => knuthShuffle(
        (`alpha beta gamma delta epsilon zeta
              eta theta iota kappa lambda mu`)
        .split(/\s+/)
    );

    // GENERIC FUNCTIONS ----------------------------------

    // enumFromTo :: Int -> Int -> [Int]
    const enumFromTo = (m, n) =>
        n >= m ? (
            iterateUntil(x => x >= n, x => 1 + x, m)
        ) : [];

    // iterateUntil :: (a -> Bool) -> (a -> a) -> a -> [a]
    const iterateUntil = (p, f, x) => {
        let vs = [x],
            h = x;
        while (!p(h))(h = f(h), vs.push(h));
        return vs;
    };

    // randomRInt :: Int -> Int -> Int
    const randomRInt = (low, high) =>
        low + Math.floor(
            (Math.random() * ((high - low) + 1))
        );

    return test();
})();