On Wed 13 Apr 2011 19:31, Wolfgang J Moeller <w...@heenes.com> writes:
> Last resort: Once we do allow for argument(s) to (break),
>
> (while #t ... (break x) ... (break y) ...)
If I understand you right, this is more like a coroutine, which could
use an orthogonal form:
(define-syntax with-yield
(lambda (x)
(syntax-case x ()
((_ yield exp exp* ...) (identifier? #'yield)
#'(let ((tag (make-prompt-tag)))
(define (handler k . args)
(define (resume . args)
(call-with-prompt tag
(lambda () (apply k args))
handler))
(apply values resume args))
(call-with-prompt
tag
(lambda ()
(let-syntax ((yield (syntax-rules ()
((_ arg (... ...))
(abort-to-prompt tag arg (... ...))))))
exp exp* ...))
handler))))))
Then you can
(with-yield yield
(while #t ... (yield) ...))
Regards,
Andy
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