[R6RS] Core/library split: `syntax-rules'

[Anton van Straaten]

> Shouldn't we have `syntax-rules' in the core?

Since there are already two essentially independent macro systems in 
R6RS, and since implementations provide other systems, I didn't think 
any single system should be imposed at that level.

This perhaps relates to an issue which I don't think we've settled yet: 
the original core/library split proposal proposed three sets of library 
combinations (r6rs-small, r6rs, and r6rs-big).  I would expect all of 
those to contain a macro system: I proposed syntax-rules in r6rs-small, 
and both syntax-rules and syntax-case in the other two.

Anton