iota.clj

(use 'clojure.walk)

(defmacro using-iota [& body]
  (let [iota  (gensym "iota")
	forms (map #(postwalk-replace {'iota `(swap! ~iota inc)} %) body)]
    `(let [~iota (atom -1)]
       ~@forms)))

(using-iota
 (let [c0 iota
       c1 iota
       c2 iota]
   ;; [c0,c1,c2] = [0,1,2]
   (println c0 c1 c2)))

(using-iota
 (let [a (bit-shift-left 1 iota)
       b (bit-shift-left 1 iota)
       c (bit-shift-left 1 iota)]
   ;; [a,b,c] = [1,2,4]
   (println a b c)))