Getting Started

The simplest way to get started with Compojure is to use Leiningen. Installing Leiningen is straightforward, and instructions to do so can be found on the Clojure Assembla Wiki.

Once Leiningen is installed, use it to create a new Clojure project:

$ lein new hello-www
$ cd hello-www

This will create a basic project skeleton we can build upon. Update project.clj in the current directory to include Compojure 0.5.3 and the Ring Jetty adapter as dependencies:

(defproject hello-www "1.0.0-SNAPSHOT"
  :description "A Compojure 'Hello World' application"
  :dependencies [[org.clojure/clojure "1.2.0"]
                 [org.clojure/clojure-contrib "1.2.0"]
                 [compojure "0.5.3"]
                 [ring/ring-jetty-adapter "0.3.1"]])

Next, use Leiningen to download the project dependencies for you:

$ lein deps

Now you’re ready to write the application. Put the following code into src/hello_www/core.clj:

(ns hello-www.core
  (:use compojure.core)
  (:require [compojure.route :as route]))

(defroutes example
  (GET "/" [] "<h1>Hello World Wide Web!</h1>")
  (route/not-found "Page not found"))

To run this application, start a REPL using Leiningen

$ lein repl

Then pass your routes to the Jetty adapter.

=> (use 'ring.adapter.jetty)
=> (use 'hello-www.core)
=> (run-jetty example {:port 8080})

Visit http://localhost:8080 to see the results. If all has gone well, you’ll see your "Hello World" page.