Hi Damien
Your macro might work on some implementations, but is not R5RS compliant.
Ellipses ("...") must always be the last item of a list or vector before
the closing ")", (unless the last item is a pair).
If you want a general solution, I think you should go for this:
(define-syntax case*
(syntax-rules (else)
((case* (key ...)
clauses ...)
(let ((atom-key (key ...)))
(case* atom-key clauses ...)))
((case* key
(else result1 result2 ...))
(begin result1 result2 ...))
((case* key
((atoms ...) result1 result2 ...))
(if (member key '(atoms ...))
(begin result1 result2 ...)))
((case* key
((atoms ...) result1 result2 ...) clause clauses
...)
(if (member key '(atoms ...))
(begin result1 result2 ...)
(case* key clause clauses ...)))))
Best regards
Bent
2017-01-20 16:24 GMT+01:00 <[email protected]>:
> Hi Marc,
>
> Nice to see you here ;-)
>
> > Note that you can use symbols with the case construct. In other words,
> these two expressions are equivalent if str is a string:
> >
> > (cond ((string=? str "foo") 111)
> > ((string=? str "bar") 222)
> > (else 333))
> >
> > and
> >
> > (case (string->symbol str)
> > ((foo) 111)
> > ((bar) 222)
> > (else 333))
> Agree with a minor warning. Although its probably not a problem in that
> particular situation but in my own programs I try to limit the use of
> symbols
> as much as possible as these objects are never collected.
>
> --
> Manuel
>
