More tagbody

["Are Meisfjord" <are at meisfjord dot com>]

Thanks for all the advice on tagbody! Letrec will certainly be better
than my original implementation. Below you can see the "manual
expansion" (I will rewrite the macro later) of a test case from
Franz' documentation. It returns 15, just as it's supposed to.

http://www.franz.com/support/documentation/5.0.1/ansicl/dictentr/tagbo
dy.htm

(define (test)
  (let ((val '()))
    (try-catch
     (letrec ((start (lambda ()
		       (set! val 1)
		       (point-a)
		       (throw (make <java.lang.RuntimeException>))
		       (set! val (+ val 16))
		       (point-c)))
	      (point-c (lambda ()
			 (set! val (+ val 04))
			 (point-b)
			 (throw (make <java.lang.RuntimeException>))
			 (set! val (+ val 32))
			 (point-a)))
	      (point-a (lambda ()
			 (set! val (+ val 02))
			 (point-c)
			 (throw (make <java.lang.RuntimeException>))
			 (set! val (+ val 64))
			 (point-b)
			 (throw (make <java.lang.RuntimeException>))))
	      (point-b (lambda ()
			 (set! val (+ val 08)))))
       (start))
     (e <java.lang.RuntimeException> (+)))
    val))

As you can see I get away with at most one exception thrown per
tagbody (any suggestions on how to get rid of it?), which is much
better than what I had originally. Again, thanks a lot! 

Regards,


Are