2020年7月15日(水) 6:16 John Cowan <xxxxxx@ccil.org>:

On Tue, Jul 14, 2020 at 5:13 AM Marc Nieper-Wißkirchen <xxxxxx@nieper-wisskirchen.de> wrote:

(5) Implementations should provide a way to (globally) set feature
identifiers for the use in cond-expand.

I am fine with this, but it has nothing to do with SRFI 145; it should just be a recommendation of SRFI 2xx. The matter was considered in WG1 but rejected, I think; there was definitely a Chibi ticket that Alex turned down.

It is implementation defined and must remain so due to its nature and complexity in the face of separate compilation.

Chibi does not currently have separate compilation, so things are easier. Chibi allows defining features at startup with the -D option, e.g.

$ chibi-scheme -Ddebug -msrfi.189.test -e'(run-tests)'

Even here you have to be careful though, since the -D must come before the -m, otherwise the feature would be added after the libraries are loaded. Providing a procedural API would be almost meaningless, since the entire program would be compiled before any features were defined, and they would only in theory affect `eval`.

Alex