> Chibi and Larceny currently use the R5RS
> (syntax-rules) implementation.  But Larceny has syntax-case because it is
> an R6RS system, and Chibi has syntax-case thanks to Marc.  The portable
> R6RS implementation should be tested on those.

The portable R5RS, R6RS and R7RS implementations are all the same
syntax-rules based code. The R6RS and R7RS ones just add a library
wrapper according to each standard.

Strictly speaking, the R5RS code is non-standard since it requires the
syntax-rules tail patterns extension. R6RS and R7RS have tail patterns
in the standard so it's a non-issue.

The portable R7RS implementation has been tested precisely on Larceny
and Chibi. I'm not using syntax-case for either of them. The R6RS
implementation (which differs only in the library wrapper) has been
tested on Larceny among others. The testing details are all in the
SRFI's Implementation section.

> If it works, then we can
> heave the syntax-rules implementation overboard as far as I am concerned,
> and eliminate the need for the parens in favor of a syntactic keyword like
> &keys.  Best of all worlds.

Why is &key better? Would you like it in keyword-call in addition to
keyword-lambda? I think it's a worse alternative.