title: What is a re-entrant parser?
body: <p>Can someone explain this to me? In particular the difference between:</p>
  
  <p><a href="http://github.com/whymirror/greg" rel="noreferrer">http://github.com/whymirror/greg</a> and <a href="http://piumarta.com/software/peg/" rel="noreferrer">http://piumarta.com/software/peg/</a></p>
  
  <p>The former being a re-entrant version of the later.</p>