On Wed, Apr 17, 2013 at 9:21 PM, John Cowan <[email protected]> wrote:

> 張書瀚 scripsit:
>
> > But the problem of begin, as I said before, is still there.  I don't
> > think it's good to deliberately leave that behavior unspecified
> > in the standard, so I post it here (for me, it creates unnecessary
> > misunderstandings).
>
> It's a hard problem.  Suppose you are using a Scheme system like Chicken
> or Gambit, that compiles Scheme code to stand-alone executables.  What do
> you expect this to do?
>
> (call/cc (lambda (x) (x)))
>

Looks like the same as (values) to me.   Is there any reason why this might
not be the case?

I just tested this on Chicken, and it works as expected -- both using the
csi repl, and in a compiled program.

But, in general, I do agree that capturing a continuation and re-executing
it through REPL code shouldn't be relied upon to behave in any predictable
way.


>
> There just isn't any good answer, because the captured continuation is
> outside Scheme.  Likewise, if you run something like this from a REPL,
> you are capturing a continuation in the REPL's own code, which may or
> may not be in Scheme.
>
> Such issues are inherently outside the scope of any Scheme standard.
>
> --
> John Cowan   [email protected]    http://ccil.org/~cowan
> You cannot enter here.  Go back to the abyss prepared for you!  Go back!
> Fall into the nothingness that awaits you and your Master.  Go! --Gandalf
>
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