>     But are the different keyword _objects_ incompatible with each other?
>
> I suppose it would work, but it means that the calling code wouldn't be
> portable, of course.

That's true. But it's quite difficult to maintain complex programs
without keyword arguments since it's almost impossible to plan years
ahead what arguments are needed in some procedures. Therefore it would
really help the community to have keywords figured out.

This could make another case for that #!(srfi 88) facility discussed
some time ago on this list to enable or disable the syntax extensions
from particular SRFIs. (Or John's preference without parens, #!srfi 88)
For example, if a source file uses SRFI 88 style keywords it could have
#!(srfi 88) at the start. If it used Common Lisp style keywords, it
could have #!cl-keywords or something (haven't thought about this).

This would enable each source file, plus the REPL, to separately choose
its own keyword syntax. One implementation could support all of them
this way. Would there be problems with this approach?