Auto-reload pages on REPL function definition

(ns toucher.core
  (:require [clojure.java.io :as io]
            [robert.hooke :as rh :only [append]]))

(defn- touch-file
  "Called on defn invocation; updates the mod time on the reload trigger
   file so LiveReload will reload the web page."
  [file-to-touch]
  (let [f (java.io.File. file-to-touch)]
    (if (.exists f)
      (.setLastModified f (System/currentTimeMillis))
      (with-open [w (io/writer f)]))))

(defn touch-file-on-defn
  "Starts touching the specified file every time a function is defined.

   In your startup code, call

      (toucher.core/touch-file-on-defn \"some-filename.trigger\")

   and configure LiveReload to watch for changes to .trigger files in your
   directory. (Use whatever extension you want; .trigger has no special
   meaning.) Now when you send a function definition to the REPL either
   directly from the REPL prompt or remotely from vim-fireplace or another
   tool, LiveReload will see the update of the trigger file and automatically
   reload the web page so you don't have to remove focus from your terminal
   window."
  [file-to-touch]
  (rh/append defn (touch-file file-to-touch)))