I don't really like have the call-with-values and apply there, so
here's another version. It makes the macro a bit longer with the
additional case and has the pattern duplicated once, but it seems
worth it:
(define-syntax cas-cad-e
(syntax-rules ()
[(_ e) (begin e (void))]
[(_ e [(n ...) code ...] ... [(n_l ...) code_l ...])
(let/ec esc
(syntax-parameterize
([break (make-rename-transformer #'esc)])
(let* ([tmp e]
[earlier? #f]
[earlier?
(if (or earlier? (equal? tmp n) ...)
(begin code ... #t)
earlier?)]
...)
(when (or earlier? (equal? tmp n_l) ...)
code_l ...))))]))
Regarding Shriram's bug. The only thing that occurs to me is that
you'd want eqv? and a ' on the ns, to be more like case.
Jay
On Fri, Oct 8, 2010 at 10:39 PM, Jay McCarthy <jay.mccar...@gmail.com> wrote:
> You got me
>
> Sent from my iPhone
>
> On Oct 8, 2010, at 10:33 PM, Eli Barzilay <e...@barzilay.org> wrote:
>
>> 8 minutes ago, Jay McCarthy wrote:
>>> Alright, here's the version with no mutation:
>>
>> (cas-cad-e 1 [(1) (values 1 2 3)])
>>
>> In other words:
>>
>> (define-syntax-rule (cas-cad-e e [(n ...) code ...] ...)
>> (let/ec esc
>> (syntax-parameterize ([break (make-rename-transformer #'esc)])
>> (let*-values ([(tmp) e]
>> [(earlier? ret) (values #f (void))]
>> [(earlier? ret)
>> (if (or earlier? (equal? tmp n) ...)
>> (values #t (call-with-values (lambda () code ...)
>> list))
>> (values earlier? ret))]
>> ...)
>> (apply values ret)))))
>>
>> --
>> ((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay:
>> http://barzilay.org/ Maze is Life!
>
--
Jay McCarthy <j...@cs.byu.edu>
Assistant Professor / Brigham Young University
http://teammccarthy.org/jay
"The glory of God is Intelligence" - D&C 93
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