title: Is there a build tool based on inotify-like mechanism
body: <p>In relatively big projects which are using plain old <code>make</code>, even building the project when nothing has changed takes a few tens of seconds. Especially with many executions of <code>make -C</code>, which have the new process overhead.</p>
  
  <p>The obvious solution to this problem is a build tool based on <code>inotify</code>-like feature of the OS. It would look out when a certain file is changed, and based on that list it would compile this file alone.</p>
  
  <p>Is there such machinery out there? Bonus points for open source projects.</p>