spariev

(defn cc-rev
  [s]
  (let [paren? (fn [ch] (or (= ch \() (= ch \))))]
    (apply str
	   (concat
	    (flatten
	     (->> s
		  (partition-by paren?)
		  (remove #(paren? (first %)))
		  (map-indexed (fn [idx ss] (if (odd? idx) (reverse ss) ss)))))))))