(defn create-object-output-stream
  [filename]
  (if (file-exists? filename)
    (-> filename (FileOutputStream. true) AppendingObjectOutputStream.)
    (-> filename (FileOutputStream. true) ObjectOutputStream.)))

(defn write-to-file
  [file-key, data-map]
  (with-open [obj-out (-> file-key determine-filename create-object-output-stream)]
    (try
      (.writeObject obj-out, (replace-functions-by-symbols data-map))
      (.flush obj-out)
      (catch Throwable t
        (debug-repl "write-to-file")))))


(defn read-from-file
  [file-key]
  (let [filename (determine-filename file-key)]
    (with-open [obj-in (-> filename FileInputStream. ObjectInputStream.)]
      (loop [result (transient [])]
        (try
          (let [obj (.readObject obj-in)]
            (recur (conj! result obj)))
          (catch EOFException eof
            (persistent! result))
          (catch Throwable t
            (println t)
            (debug-repl "read-from-file")))))))