gistfile1.clj

(defn login-view [flash]
  (html [:html   
         [:body
          [:h2 "Login"]
          (if-let [message (:message flash)]
            [:h4 message])
          (form-to [:post "/login"]
            (text-field :username)
            (password-field :password)
            (submit-button "Login"))]]))

(defn login-controller [params request]
  (if (= (:password params) "secret")
    [(session-assoc :username (:username params))
     (redirect-to "/home")]
    [(flash-assoc :message "Login failed.")
     (redirect-to "/login")]))

(defn home-view [username]
  (html
   [:html
    [:body
     [:h2 "Home"
      [:p (str  "Hello " username ".")]]]]))

(defn home-controller [session]
  (if-let [username (:username session)]
    (home-view username)
    (redirect-to "/login")))

(defroutes app   
  (GET  "/login" (login-view flash))
  (POST "/login" (login-controller params request))
  (GET  "/home"  (home-controller session)))

(decorate app
  (with-session))

(run-server {:port 8080} "/*" (servlet app))