In Scheme/Lisp, there's two extremes for macros. At one extreme, we have "hygienic" macros which is just Lisp code that runs at compile time with signature
List<SExp> -> List<SExp>. At the other extreme, we have Racket like hygienic macros.
Question: is there any Rust crate that implements a Scheme with hygienic macros? I'm trying to learn how to do such an implementation in Rust.