filter(function, list) {
    filtered-list = ();

    for element in list {
        if (function(element)) {
            push(filtered-list, element);
        }
    }

    return filtered-list;
}

quicksort(list) {
    if (length(list) == 0) {
        return ();
    }

    pivot = list[0];
    sorted = ();

    remaining = ();
    i = 0;
    for element in list {
        if (i != 0) {
            push(remaining, element);
        }
        i = i + 1;
    }

    smaller-sorted = quicksort(filter(@(num) {
        return num <= pivot;
    }, remaining));

    bigger-sorted = quicksort(filter(@(num) {
        return num > pivot;
    }, remaining));

    push(sorted, smaller-sorted, pivot, bigger-sorted);

    return sorted;
}

#out {
    sorted-numbers: quicksort((5 93 6 13 72 45 7 82 9 63 2));
}

See the Pen yyYLQw by Martin Jinda (@Mardzis) on CodePen.