Re: [Scheme-reports] Fwd: Comments on draft 6 about call/cc
Alaric Snell-Pym 20 Feb 2012 10:32 UTC
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On 02/20/2012 09:48 AM, Andy Wingo wrote:
> Why generators, when delimited continuations can implement them
> trivially?
It has been my understanding that delimited continuations are generally
better than call/cc in all ways. Even things like amb can be implemented
with them, adding the restriction that one must introduce an outer
"wrapper" construct that dynamically encloses all nondeterministic
evaluation in order to delimit the continuations - but that is arguably
a feature, as it stops the confusing that arises when people use amb at
a repl and end up backtracing inside the repl state (without
backtracking the state of standard input, of course) and get themselves
terribly confused!
Now, is my understanding that (> call/pc call/cc) true in all cases, or
not? Does anybody know of any counter-examples?
Clearly, it's far too late for call/cc to be replaced by delimited
continuations for R7RS, but it would be nice to decide if it might be
worth considering for R8RS (along with immutable-by-default pairs,
perhaps? :-)
ABS
- --
Alaric Snell-Pym
http://www.snell-pym.org.uk/alaric/
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