sicp.clj

(defn fast-expt [b n]
  (loop [acc 1 
	 b b 
	 n n]
   (cond
    (= n 0) acc
    (even? n) (recur acc (* b b) (/ n 2))
    :else (recur (* acc b) b (dec n)))))

(defn mult [a b]
  (loop [acc 0
	 a a
	 b b]
    (cond
     (= b 1) (+ a acc)
     (even? b) (recur acc (* a 2) (/ b 2))
     :else (recur (+ a acc) a (dec b)))))