What are the most popular R4RS implementations? I want to use R4RS. It is less bloated than R5RS.
If you care about bloat, write your own interpreter or fork and strip and existing one.
>>2
I was thinking this as well, but did not speak up.
"Scheme 9 from Empty Space" is an R4RS Scheme implementation that is in the public domain.
There is also a book that explains its source code: "Scheme 9 from Empty Space: A Guide to Implementing Scheme in C" by Nils M. Holm.
You could write your own implementation based on the material presented in "Lisp in Small Pieces" by Christian Queinnec.