Nitpicking:
> immutable strings (which racket has not)
The reader makes strings in the sour code immutable by default. And if you have a mutable string you can use string->immutable-string https://docs.racket-lang.org/reference/strings.html#%28def._...
Yeah. I should have been more clear. I meant as the default. There are all kinds of nice optimizations that can be done with immutable strings compared to mutable ones. Which I probably don't have to tell you, Gustavo :) I have been reading every patch you have made to chez, not understanding half of it but loving every moment.
Add to that some better facilities for mixing languages and it is a very nice language that is very close to racket. Yet for some reason I find guile more fun.