That sounds horrible. What are better resources?
Discussed here, a few times:
Mal – Make a Lisp - https://news.ycombinator.com/item?id=26924344 - April 2021 (40 comments)
Mal – Make a Lisp, implemented in 79 languages - https://news.ycombinator.com/item?id=21670442 - Nov 2019 (11 comments)
Mal – Make a Lisp, in 68 languages - https://news.ycombinator.com/item?id=15226110 - Sept 2017 (69 comments)
Make your own Lisp - https://news.ycombinator.com/item?id=13967401 - March 2017 (32 comments)
Mal – Make a Lisp - https://news.ycombinator.com/item?id=12720777 - Oct 2016 (1 comment)
Make a Lisp in Nim - https://news.ycombinator.com/item?id=9145360 - March 2015 (44 comments)
Make a Lisp - https://news.ycombinator.com/item?id=9121448 - Feb 2015 (41 comments)
Lisp implemented in under 1K of JavaScript - https://news.ycombinator.com/item?id=9109225 - Feb 2015 (16 comments)
Writing a Lisp in Ocaml: https://bernsteinbear.com/blog/lisp/00_fundamentals/
Not Lisp-specific but Crafting Interpreters is also great: https://craftinginterpreters.com/
Be aware that it's some 500 pages and makes several interpreters then a couple of compilers as I recall. If you read it though, you'll come out the other end with a pretty good understanding of how lisp implementations actually work.
It takes a very thoughtful approach to introducing an increasingly complex Scheme implementation. I doesn't shy away from the complexity that many LISP implementation tutorials try to push under the rug.
[edit - though it looks like handlebars (that I use for generating HTML from templates) has about 30k lines in files that end in .js, so maybe twitter is 30m lines of code?]
[second edit - hmm... maybe i'll change the name to "mini-blog" to signal it's a blog that's 25% the performance of a "mainframe-blog" but 10% the cost. though "mini-blog" might be more appropriate: halfway between a "normal" blog entry and a "micro-blog."]