I'm not sure if it satisfies all your needs,
but Scheme 9 from Empty Space is a full R4RS Scheme implementation written from scratch in pure C (and Scheme).
It has a heavily commented source code and a book, which is supposed to be quite good.
Here are some key points from the website which the book addresses:
- How does tail call elimination work?
- How is macro expansion implemented?
- How is arbitrary precision arithmetics implemented?
Here are some key points from the website which the book addresses:
- How does tail call elimination work?
- How is macro expansion implemented?
- How is arbitrary precision arithmetics implemented?
Enjoy! http://t3x.org/s9book/index.html