/* Shannon entropy, in Jsish */

function values(obj:object):array {
    var vals = [];
        for (var key in obj) vals.push(obj[key]);
    return vals;
}

function entropy(s) {
    var split = s.split('');
    var counter = {};
    split.forEach(function(ch) {
        if (!counter[ch]) counter[ch] = 1;
        else counter[ch]++;
    });

    var lengthf = s.length * 1.0;
    var counts = values(counter);
    return -1 * counts.map(function(count) {
        return count / lengthf * (Math.log(count / lengthf) / Math.log(2));
        })
        .reduce(function(a, b) { return a + b; }
    );
};

if (Interp.conf('unitTest')) {
;    entropy('1223334444');
;    entropy('Rosetta Code');
;    entropy('password');
}