Thanks to a tweet from Tiago Charters de Azevedo, I learned today that Mozilla’s CVS tree still contains the original implementation of Javascript written in Common Lisp. I always found interesting to see examples of Lisp being used in places most people wouldn’t dream of (even if later it’s replaced by another language implementation).

The README states:

“js/semantics contains experimental code used to generate LR(1) and LALR(1) grammars for JavaScript as well as compile and check formal semantics for JavaScript. The semantics can be executed directly or printed into either HTML or Microsoft Word RTF formats. This code is written in standard Common Lisp. It’s been used under Macintosh Common Lisp 4.0, and Allegro Common Lisp 5.0.1 for Windows, but should also work under other Common Lisp implementations.”

Now I need to take a look at this code more carefully, just for the fun of it!