From some leaked info and old post by pg, a big part is done in the REPL and the functions are updates on the fly. Also, from time to time, you will see a messa

From some leaked info and old post by pg, a big part is done in the REPL and the functions are updates on the fly. Also, from time to time, you will see a message that says something like "The server is restarting, it should take a minute." Last year dang changed the backend from Arc-on-Racket to Arc-on-SBCL with a minimal downtime that was mostly unnoticed.