I just tried this out, this is amazing!

It does actually have a lot of R7RS support (like #!fold-case) however it doesn't seem to work with polar complex numbers (e.g; 2@1.5) or complex numbers with infnan (e.g; 3+inf.0i or +inf.0+3i).

more about the implementation: https://www.lisppad.app/applications/language