The following all intend to support R7RS small:
- Per Bothner (Kawa)
- Will Clinger (Larceny)
- Shiro Kawai (Gauche)
- Manuel Serrano (Bigloo) – “not sure about libraries”
- Alex Shinn (Chibi) – “already fully implemented, but lacking tests”
- Felix Winkelmann (Chicken)
The following were less committal, but open, and their implementations are flexible enough to implement R7RS in third-party code:
- Kent Dybvig (Chez) – “if it’s as simple as you say I don’t see why not”
- Matthew Flatt (Racket) – “if there’s sufficient user demand”
- Andy Wingo (Guile) – “probably”
The following are simply unable to implement R7RS or uninterested in standards:
- Taylor Campbell (MIT) – “MIT lacks the infrastructure for modules”
- Jonathan Shapiro (TinyScheme) – thinks call/cc should be removed
- Jeffery Mark Siskind (Stalin) – “no longer working on Stalin”
- Michael Sperber (Scheme48) – “no time even for R6RS”
No one refused to implement based on the content of the standard, or cited any features as showstoppers.
That last part is important; R6RS didn’t have that quality.
(via scheme-reports)