On 2012-05-14 19:00:49 -0600, Matthew Flatt wrote:
> In other words, every `parameterize' uses the same continuation mark,
> so that `(parameterize ([r 10]) ...)' associates the parameterization
> continuation mark with a single record that maps `r' to 10, `p' to 1,
> etc. The entire record is carried by the delimited continuation.
Thanks Matthew and Ryan, that clears it up. OTOH, it does look like a
straightforward translation to continuation marks (or using
unstable/markparam as Ryan pointed out) doesn't get the 12 result
either.
For example:
#lang racket
(require racket/control
unstable/markparam)
(define p (mark-parameter))
(define r (mark-parameter))
((λ (f)
(mark-parameterize ([p 2])
(mark-parameterize ([r 20])
(f 0))))
(mark-parameterize ([p 1])
(reset
(mark-parameterize ([r 10])
((λ (x) (+ (mark-parameter-first p)
(mark-parameter-first r)))
(shift f f))))))
Will produce an error
+: expects type <number> as 1st argument, given: #f; other arguments were: 10
> In the ICFP'07 paper on delimited continuations in Racket, we wrote (at
> the end of section 5) that we'd probably change `parameterize', but
> we've never gotten around to that change. Meanwhile, raw continuation
> marks (as modeled directly in that paper) essentially match the
> dynamic-binding form of Kiselyov et al.
The raw continuation mark version gives essentially the same error as
above, maybe because call/cc and call/comp restore the marks to what was
present at capture time, which doesn't include the `p` mark?
Cheers,
Asumu
____________________
Racket Users list:
http://lists.racket-lang.org/users
