title: How to enable language extensions / pragmas project wide by default?
body: <p>Is there a way to put <code>{-# LANGUAGE &lt;feature&gt; #-}</code> pragmas in either the:</p>
  
  <ul>
  <li><code>&lt;project&gt;.cabal</code>, or</li>
  <li><code>stack.yaml</code></li>
  </ul>
  
  <p>file, to avoid repeating the same header code in every <em>*.hs</em> file of a project?</p>