static void onFileChange(double seconds, final File file, final long lastModificationSeen, final Runnable r) {
  doEvery_daemon(toMS(seconds), new Runnable {
    long lastMod = lastModificationSeen;
    
    public void run() {
      long mod = file.lastModified();
      if (mod != lastMod) {
        lastMod = mod;
        call(r);
      }
    }
  });
  
  call(r);
}

Began life as a copy of #1004395