Comment by vidarh

I wrote one, though it kinda got away from me (I started very simple, but then started turning it into a Ruby compiler):

https://hokstad.com/compiler

On that note, while there's no new part, after finally revisiting it for the first time in a couple of years, it now compiles itself (from Ruby into 32bit x86).

A few very critical bugs that I'm working on, and a lot of big omissions (no Regexp yet; the Ruby Regexp engine source is bigger than my entire compiler, nor any Floats; syntax lacks a lot of newer features) so it's very much not a usable Ruby at this point. Maybe one day if I get more time.

If you find it interesting, I'd recommend looking at the earlier parts rather than the current source. Lots of the recent changes were very aggressively working around bugs to move it towards self hosting, and it's not pretty.