<br><br><div class="gmail_quote">On Mon, Aug 2, 2010 at 15:23, Keiko Nakata <span dir="ltr"><<a href="mailto:keiko@kurims.kyoto-u.ac.jp">keiko@kurims.kyoto-u.ac.jp</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> Hi,<br> <div class="im"><br> From: Matthew Flatt <<a href="mailto:mflatt@cs.utah.edu">mflatt@cs.utah.edu</a>><br> <br> </div><div class="im">> At Mon, 02 Aug 2010 21:54:54 +0900 (JST), Keiko Nakata wrote:<br> </div><div class="im">> > Why this code<br> > ><br> > > (let ([d (box #f)] [a (box 0)])<br> > > (print (+ (begin (let/cc k (begin (set-box! d k) (set-box! a 2) 3))) (unbox<br> > > a)))<br> > > ((unbox d) 9))<br> > ><br> > > prints 511111111, rather than 59999999?<br> ><br> > I'm not sure I'm following. Can you say more about why you expect<br> > infinite "9"s instead of infinite "11"s?<br> <br> </div>I wanted to undo the assignment (set-box! d k), but I think I am confusing.<br> I'm a novice to continuations...<br> <br> I used begin to enforce sequentiality, but seemed to be trapped by it.<br></blockquote><div><br>Maybe you could use `(let () <i>body ...</i>)' instead? It should be closer to your intentions.<br></div></div>