title: What is the inverse of intercalate, and how to implement it?
body: <p><a href="https://stackoverflow.com/questions/19810938/scala-combine-two-lists-in-an-alternating-fashion/">This question</a> discusses how to interleave two lists in an alternating fashion, i.e. <em>intercalate</em> them.</p>
  
  <ul>
  <li>What is the inverse of "intercalate" called?</li>
  <li>Is there an idiomatic way to implement this in Scala?</li>
  </ul>