a middleware to remove utm_… params from query strings

gistfile1.clj

(require '[clojure.string :as str])
(use '[ring.util.response :only [redirect]])

(defn remove-utm-params)
  [query-string]
  (->> (.split query-string "&")
       (filter (fn [^String p] (.startsWith p "utm_")))
       (str/join "&")))

(defn utm-redirect
  "I hate having utm crap uglying up my URLs."
  [app]
  (fn [req]
    (let [qs ^String (or (:query-string req) "")]
      (if (.contains qs "utm_")
        (let [qs (remove-utm-params qs)]
          (redirect (str (:uri req) (when (not= "" qs) (str "?" qs)))))                                                                
        (app req)))))