I have been following the development of some open source scheme compilers (chez and guile) and I'm always impressed by the work people do there. The chez code

I have been following the development of some open source scheme compilers (chez and guile) and I'm always impressed by the work people do there. The chez code is amazing in most places, and I can understand why racket chose it as their base. Guile has been getting some really neat optimizations lately (jit, declarative modules, efficient local recursive bindings and much more) and it is really fun to try to follow the code that gets published. Andy's blog over at wingolog.org is also great fun to read.