Creates memoised function.

defn-memo.clj

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; create memoised func
;;
;; momoize in clojure 1.2 and after does not work as I expected. So, I created this macro.
 
(defmacro defn-memo 
  "Creates memoised function.
   Also creates:
     accessor of the memoized data which named <fname>-data.
     resetter of the memoized data which named <fname>-crear."
  [fname arg-list & body]
  `(let [mem# (atom {})]

     (defn ~(symbol (str (str fname) "-data")) []
       @mem#)

     (defn ~(symbol (str (str fname) "-clear")) []
       (reset! mem# {}))

     (defn ~fname ~arg-list
       (if-let [e# (find @mem# ~arg-list)]
	 (val e#)
	 (let [ret# ~@body]
	   (swap! mem# assoc ~arg-list ret#)
	   ret#)))))