Ring solution to redirect missing trailing slash urls

wrap_slash.clj

;;; http://stackoverflow.com/questions/14507445/ring-solution-to-redirect-missing-trailing-slash-urls

(defn good-response? [resp]
  (and resp (not= (:status resp) 404)))

(defn wrap-slash [handler]
  (fn [{:keys [uri] :as req}]
    (let [resp (handler req)]
      (if (or (good-response? resp) (.endsWith uri "/"))
        resp
        (let [added-slash (str uri "/")]          
          (if (good-response? (handler (-> req
                                           (assoc :uri added-slash)
                                           (assoc :path-info added-slash))))
            (redirect added-slash)
            resp))))))