A middleware to log Ring request/response to a file.

wrap-logging.clj

(def logger (agent nil))
(def logfile (java.io.FileWriter. "output.edn"))

(defn log [a x]
  (binding [*out* logfile
            *print-length* 200]
    (prn x)))

(defn wrap-logging [hdlr]
  (fn [req]
    (let [resp (hdlr req)]
      (send-off logger {:request req :response resp})
      resp)))