quicksort

(defn quick-sort [xs]
    (if (empty? xs)
        []
        (let [head (first xs) tail (rest xs)]
            (concat
                (quick-sort (filter #(<= % head) tail))
                [head]
                (quick-sort (filter #(> % head) tail))))))

(let [xs (sort-by rand (range 1 20))]
    (println xs)
    (println (quick-sort xs)))