My Clojure, Ring, Compojure development setup

I had to search several sources (like this) to get this setup, so I thought it would be useful to summarize my setup here. Unlike most developers, I use five different editors (emacs+slime+swank, IntelliJ IDE, GEdit, e, and Textmate) depending on which computer and OS I am on. I wanted to be able to leave a Compojure based web app running in development mode and have source files refresh regardless of which editor I am using. In the following example, I have two Clojure source files: one with Ring and Compojure code, and one a utility file, containing for this example an extremely useful function foo. Start by creating an empty Leiningen project:

lein new KBSportal
cd KBSportal

Then edit project.clj to look like:

(defproject kbsportal "0.1.0"
  :description "test using Compojure for KBSportal.com"
  :dependencies
    [[compojure "0.4.0-SNAPSHOT"]
     [ring/ring-devel "0.2.0-RC2"]
     [ring/ring-httpcore-adapter "0.2.0-RC2"]
     [ring/ring-jetty-adapter "0.2.0-RC2"]
     [ring/ring-servlet "0.2.0-RC2"]]
  :main kbsportal)

In the empty src directory create the file kbsportal.clj:

(ns kbsportal
  (:use compojure.core
        ring.adapter.jetty)
  (:use ring.middleware.reload)
  (:use ring.middleware.stacktrace)
  (:use nlp)) ; nlp.clj is my other source file

(defroutes test-routes
  (GET "/" []
       (str "<h1>Testing foo: " (foo) "</h1>"))
  (ANY "*" []
       {:status 404, :body "<h1>Page not found error</h1>"}))

(def app
     (-> (var test-routes)
         (wrap-reload '(kbsportal))
         (wrap-reload '(nlp))
         (wrap-stacktrace)))

(defn dev []
  (run-jetty #'app {:port 8080}))

and the file nlp.clj:

(ns nlp)

(defn foo [] " - This is from foo.") ; a very useful function!

Notice how I use the Ring wrap-reload function to force checking the date stamp on the two source files and reload them if they are changed. You would not want to check for automatic reloads in a production environment. This is a skeleton project, but in a real project you could add wrap-reload calls for new source files that you add to your project's src directory. To run in development mode, you can type:

lein repl

to start a Clojure repla and then inside the repla load the main source file and run the (dev) function:

(use 'kbsportal)
(dev)

Hit the URL http://localhost:8080 to load the test web page, edit either source file, and reload the web page to see the effects of your edits. This setup provides a quick and effective interactive development environment. If you just use emacs, then for a better alternative look for one of the excellent emacs+slime+swank Compojure-specific tutorials on the web.