Adding variadic functions to the javascript core and string conversion to the lisp side
In this video the Lisp interpreter core in Javascript is extended to support variadic functions (functions with a variable number of arguments) and the lisp side is extended by implementing a few more primitives and a string conversion function that basically does the opposite of what "read" does.
Javascript and lisp code can be downloaded from
http://raksy.dyndns.org/yt/4/lisp4.js
http://raksy.dyndns.org/yt/4/lisp.lisp