I think that's a very old version of Arc2js. There was at least one more version Pauan made after that, from scratch. Nowadays, Pauan's lisp-that-runs-on-JavaScript efforts seem to be focused on Nulan[1], which... seems to use the escodegen library[2] for JS generation.
And here I spent the weekend optimizing my own lisp-to-JS compiler, when I could've used escodegen. :-p Ah well, it'll probably be worth it because I'm very picky about stack overflows and such.
Well, that old version of Arc2js seems to be trapped in an orphaned set of commits that GitHub might garbage-collect at any time. I tried making a local mirror of the whole repo, but those commits don't come with it. Pauan probably wouldn't consider it to be code that's worth rescuing, but now's the time to figure out how to rescue it. :)
I was just looking at some of the older posts here and came across the discussion of arc2js[0]. When that link didn't work I used Google and came across another post[1] where he mentioned an updated page and that one had a link that worked. I must have accidentally copied the broken link instead of the one to the actual page.