Compojure example with Enlive template inheritance

compojure-enlive.clj

(ns list.handler
  (:use compojure.core
        ring.adapter.jetty
        [net.cgrand.enlive-html :as html])
  (:require [compojure.handler :as handler]
            [compojure.route :as route])
  (:gen-class))

(defmacro maybe-substitute
  ([expr] `(if-let [x# ~expr] (html/substitute x#) identity))
  ([expr & exprs] `(maybe-substitute (or ~expr ~@exprs))))

(defmacro maybe-content
  ([expr] `(if-let [x# ~expr] (html/content x#) identity))
  ([expr & exprs] `(maybe-content (or ~expr ~@exprs))))

(deftemplate base-view "views/base.html"
  [{:keys [content]}]
  [:#content] (maybe-substitute content))

(html/defsnippet test-view "views/test.html" [:div#content]
  [{:keys [left middle right]}]
  [:div#left]   (maybe-substitute left)
  [:div#middle] (maybe-substitute middle)
  [:div#right]  (maybe-substitute right))

(html/defsnippet user-view "views/user.html" [:div#content]
  [{:keys [id]}]
  [:span#user-id]  (maybe-substitute id))

(defn render
  ([tmpl] (tmpl {}))
  ([tmpl repl]
    (base-view {:title "Clojure List"
                :content (tmpl repl)})))

(defroutes app-routes
  (GET "/test" [] (render test-view {}))
  (GET ["/user/:id", :id #"[0-9]+"] [id] (render user-view {:id id}))
  (route/not-found "Not Found"))

(def app
  (handler/site app-routes))