Re: [Scheme-reports] About the behavior of continuation in top-level begin form
John Cowan 18 Apr 2013 01:21 UTC
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)))
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 cowan@ccil.org 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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