Am Sa., 2. Nov. 2019 um 17:21 Uhr schrieb Marc Nieper-Wißkirchen
<xxxxxx@nieper-wisskirchen.de>:
>
> Am Fr., 1. Nov. 2019 um 20:44 Uhr schrieb Lassi Kortela <xxxxxx@lassi.io>:
> >
> > Can we have a quick vote about who prefers the current option 1:
> >
> > (keyword-lambda (a b (c d e)) <lambda body ...>)
> >
> > (keyword-call foo 1 2 (e 5 c 3 d 4))
> >
> > And who would prefer option 2 where all of these are supported:
> >
> > (keyword-lambda (a b :key c d e) <lambda body ...>)
> >
> > (keyword-call foo 1 2 e: 5 c: 3 d: 4)     ; In all Schemes
> > (keyword-call foo 1 2 :e 5 :c 3 :d 4)     ; In all Schemes
> > (keyword-call foo 1 2 #:e 5 #:c 3 #:d 4)  ; In Schemes that have #:
> >
> > Option 1 can be implemented with syntax-rules and tail patterns.
> >
> > Option 2 needs syntax-case, explicit-renaming, or define-macro. It can
> > be implemented equally well in Schemes that have native read syntax for
> > keywords, and Schemes that don't. The trick is to treat a symbol
> > starting or ending with a colon as a keyword.
>
> How do you want
>
> (let ((:e 3))
>   (keyword-call foo 1 2 :e 4))
>
> being handled?
>
> While Option 2 looks much better than Option 1, it doesn't seem to
> work well when the underlying Scheme does not have a separate keyword
> type (and keyword syntax).
>
> So what about the following Option 3?
>
> (keyword-call foo 1 2 : e 5)
>
> In Schemes with a keyword reader syntax, it can be expressed as
>
> (keyword-call foo 1 2 #:e 5)
>
> Option 3 is also implementable using syntax-rules alone.

P.S.:

And keyword-lambda (lambda/kw) could be:

(lambda/kw (a b c : e x <default> ...)
  ...)

If possible, lambda/kw should become a synonym of lambda (and the
syntax of define should allow keywords as well).