http://siscia.github.io/programming/2013/08/10/persisten-memoizazion/

simple-persistent-memorize.clj

(import '[java.io PushbackReader])

(defn make-name [f]
  (str "memo/" (clojure.string/replace (str f) #" " "") "-memo-function.clj"))

(defn- open-memo-file [name]
  (let [name (make-name name)]
    (try
      (with-open [r (clojure.java.io/reader name)]
        (read (PushbackReader. r)))
      (catch Exception e
        (do
          (println (str "File don't exist, will create file " name))
          {})))))

(defn fake [input name]
  (fn [& args]
    (let [stored (open-memo-file name)]
      (if-let [v (get stored args)]
        v
        (let [result (apply input args)
              new-file (merge stored {args result})]
          (with-open [w (clojure.java.io/writer (make-name name))]
            (binding [*out* w
                      *print-dup* true]
              (pr new-file)))
          result)))))