Setting dotcloud env variables (not working)

main.clj

(defmacro maybe
  "Assuming that the body of code returns X, this macro returns [X nil] in the case of no error                                                                                   
  and [nil E] in event of an exception object E."
  [& body]
  `(try [(do ~@body) nil]
        (catch Exception e#
                 [nil e#])))

(defn safe-slurp
  "Slurp content of given filename. Return nil on error reading the file."
  [filename]
  (let [[text ex] (maybe (slurp filename))]
    (if ex nil text)))

;; Define dotcloud environmental values                                                                                                                                           
(defn port [& args]
  "Set the port based on the environment"
  (or
   (:PORT_WWW (generate-string (safe-slurp "/home/dotcloud/environment.json")))
   (int 8000)))

or more completely

(defn port [& args]
  (if-let [port (get (System/getenv) "PORT_WWW")]
    (Integer/parseInt port)
    8080))