Hello Daphne,

Reading through the text, I see that you mentioned not being able to
install STklos through Homebrew on your Mac. Please feel free to open
an issue on STklos' GitHub page, https://github.com/egallesio/STklos
(also if you also have problems compiling STklos from source).
By the way, STklos is also available as a Docker image:

* schemers/stklos, from Scheme containers project, and
* stklos/stklos, from the STklos maintainer.

The image for 1.70 seems to have an issue (there is a pending pull
request for it).

Anyway, I can also help testing anything myself and reporting. :)

Regarding the proposal, I don't see difficulties (except that maybe the
way STklos handles the empty keyword, ":" may need to be changed, but I
don't see that as an issue).

For reference, STklos implements something close to Common Lisp,
with the :optional and :rest keywords working in a similar way to
&key and &rest.

Jeronimo