(ns quicksort.core)

(defn quick-sort 
  ([xs] (quick-sort xs <))
  ([xs cmp]
  (if (seq xs)
    (lazy-seq 
     (let [pivot (first xs)]
       (concat (quick-sort (filter #(cmp % pivot) (rest xs)) cmp)
               [pivot]
               (quick-sort (filter #(not (cmp % pivot)) (rest xs)) cmp))))
    xs)))