ring directoryindex middleware / -> /index.html /foo/ -> /foo/index.html /foo -> /foo

handler.clj

; clojure "1.5.1"
; compojure "1.1.5"
(ns app.handler
  (:use compojure.core)
  (:require [compojure.handler :as handler]
            [compojure.route :as route]))

; middleware
(defn directoryindex [handler index]
  (fn [request]
    (let [uri (re-find #"^.*/$" (request :uri))]
      (handler
        (if uri
          (assoc request :uri (str uri index))
          request)))))

(defroutes app-routes
  (GET "/" [] "Hello World")
  (route/resources "/")
  (route/not-found "Not Found"))

(def app
  (-> (handler/site app-routes)
      (directoryindex "index.html")))