Macro to measure memory usage of an expr

mem.clj

(defn bytes-used
  "Returns bytes used by Java VM (after collecting garbage)"
  []
  (let [rt (Runtime/getRuntime)]
    (dotimes [_ 5] (System/gc))
    (- (.totalMemory rt) (.freeMemory rt))))

(defmacro mime
  "Measures and prints the bytes used while evaluating expr (returns result of expr)"
  [expr]
  `(let [mem-start# (bytes-used)
	 result# (do ~expr)]
     (println (- (bytes-used) mem-start#) "bytes used")
     result#))