Dummy implementation a websocket server via a state machine in Clojure

ws-state-machine.clj

(ns tokichat.core
  (:use org.httpkit.server)
  (:gen-class))

(defn handler [req]
  (with-channel req channel            

    (on-close channel (fn [status]
      (println "channel closed")))

    (if-not (websocket? channel) (
        (send! channel "Websocket required")
        (close channel)))
    
    (letfn [(start-fn [data]
                  (send! channel "That's interesting, tell me more about: ")
                  (send! channel data)
                  start-fn)]
    
      (let [state-func (atom start-fn)]

        (on-receive channel (fn [data] 
          (swap! state-func (@state-func data))
        ))))))

(defn -main []
  (run-server handler {:port 8080})
)