Rotate Sequence

rotate.clj

; Solving 4Clojure 44

; first try
(def rotate
  (fn [n xs]
   (if (= n 0)
     xs
     (let [nextn (* (dec (Math/abs n)) (if (< n 0) -1 1))
           nextxs (and (not= 0 n)
                       (if (< n 0)
                            (cons (last xs) (vec (butlast xs)))
                            (conj (vec (rest xs)) (first xs))))]
       (if (= n 0)
         xs
         (recur nextn nextxs))))))

; better
(defn rotate-better [n xs]
  (let [len (count xs)
        n (mod n len)
        split (if (>= n 0) n (+ n len))]
    (concat (drop split xs) (take split xs))))