(() => {
    'use strict';

    // compose :: [(a -> a)] -> (a -> a)
    const compose = (...fs) =>
        x => fs.reduceRight(
            (a, f) => f(a),
            x
        );

    // Test a composition of 3 functions (right to left)
    const
        sqrt = Math.sqrt,
        succ = x => x + 1,
        half = x => x / 2;

    return compose(half, succ, sqrt)(5);

    // --> 1.618033988749895
})();