title: What is Hindley-Milner?
body: <p>I encountered this term <em>Hindley-Milner</em>, and I'm not sure if grasp what it means.</p>
  <p>I've read the following posts:</p>
  <ul>
  <li>Steve Yegge - <a href="http://steve-yegge.blogspot.com/2008/05/dynamic-languages-strike-back.html" rel="noreferrer">Dynamic Languages Strike Back</a></li>
  <li>Steve Yegge - <a href="http://steve-yegge.blogspot.com/2007/01/pinocchio-problem.html" rel="noreferrer">The Pinocchio Problem</a></li>
  <li>Daniel Spiewak - <a href="https://web.archive.org/web/20181118000004/http://www.codecommit.com/blog/scala/what-is-hindley-milner-and-why-is-it-cool" rel="noreferrer">What is Hindley-Milner? (and why is it cool?)</a></li>
  </ul>
  <p>But there is no single entry for this term in wikipedia where usually offers me a concise explanation.<br />
  <sup><strong>Note</strong> - one has <a href="http://en.wikipedia.org/wiki/Hindley%E2%80%93Milner" rel="noreferrer">now been added</a></sup></p>
  <p>What is it?<br />
  What languages and tools implement or use it?<br />
  Would you please offer a concise answer?</p>