> Yes, I plan to name the macro "loop".

Perhaps "loop*" would be a decent alternative? By analogy to let*.

> At least in R[67]RS, it won't
> clash with locally defined variables named "loop". Thanks to the
> rename facility of the R[67]RS module system, it can also peacefully
> coexist with other loop facilities named "loop" as well.

Indeed. It's one of the best features of Scheme that it doesn't have any
reserved words. Scheme is the only language I know where the module
system isn't painful to use.