The code later got translated into C++.  However, we had a template language for describing pages that was basically Common Lisp with a few macros.  These templates are stored on disk as s-expressions.  They couldn't change the template language because some users had created their own.  So the C++ version literally had to read Lisp programs off disk and execute them.  I.e. it was a Lisp interpreter.<p>That's what I was talking about at the time when I described it somewhere as a new world record for Greenspun's tenth rule.<p><a href="http://en.wikipedia.org/wiki/Greenspun%27s_Tenth_Rule" rel="nofollow">http://en.wikipedia.org/wiki/Greenspun%27s_Tenth_Rule</a>