Clojure Jetty Hello World

app.clj

(ns app.main
  (:import
   [javax.servlet.http HttpServletResponse HttpServletRequest]
   [org.eclipse.jetty.server Request ServerConnector Server]
   [org.eclipse.jetty.server.handler AbstractHandler]
   [org.eclipse.jetty.util.thread QueuedThreadPool])
  (:gen-class))

(defn handler [^HttpServletRequest _ ^HttpServletResponse response]
  (let [writer (.getWriter (doto response
                             (.setCharacterEncoding "UTF-8")
                             (.setContentType "text/html")))]
    (.write writer "<h3>Hello world</h3>")))

(defn create-handler [handle-func]
  (proxy [AbstractHandler] []
    (handle [_ ^Request base-request ^HttpServletRequest request ^HttpServletResponse response]
      (handle-func request response)
      (.setHandled base-request true))))

(def ^Server server
  (-> (QueuedThreadPool.)
      (Server.)))

(defn init-connector []
  (ServerConnector. (doto
                     server
                      (.setHandler (create-handler handler)))))

(defn -main [& _args]
  (let [connector (init-connector)]
    (println "Hello world, the time is")
    (.addConnector server (doto connector
                            (.setPort 9966)
                            (.setHost "127.0.0.1")))

    (.start server)))