From: Neil Jerram <neil@ossau.uklinux.net>
To: Andy Wingo <wingo@pobox.com>
Cc: guile-devel <guile-devel@gnu.org>
Subject: Re: catch, throw, prompt, control, fluids, garbage collection
Date: Sun, 28 Feb 2010 22:16:24 +0000 [thread overview]
Message-ID: <87k4tx80qv.fsf@ossau.uklinux.net> (raw)
In-Reply-To: <m3iq9kdvxb.fsf@pobox.com> (Andy Wingo's message of "Fri, 26 Feb 2010 13:27:12 +0100")
Andy Wingo <wingo@pobox.com> writes:
>>> Efficient with-fluids: check! So on to figuring out the prompt and
>>> abort implementations...
>>
>> Prompt and abort: check! Now to finally implement catch, throw, and
>> all that in terms of delimited continuations... (Do I foresee a future
>> reply from myself?)
>
> Catch and throw in terms of prompt and abort: check! And passing the
> test suites, of course. Give master a pull!
Sorry for breaking the reply pattern... :-)
This all sounds like great stuff to me. I haven't understood every
detail, but it all feels very right.
One particular application that I don't think you've mentioned: it was
recently suggested to me that when a Guile program is running under a
debugger, and hits some kind of error, the debugger could offer a menu
of places in the program to jump back to. I think that would align
exactly with the set of prompt tags.
Two specific questions:
1. Right at the start of the yak, you introduced the need for the
"running" flag to be a fluid, because of the possibility of multiple
threads simultaneously using the same set of handlers. I haven't
checked how dynwinds may have changed in 1.9, but in 1.8 I'm fairly sure
that your suggestion is impossible, because each new thread would be
created with a clean dynamic context (including dynwinds), and not
inherit the context of its creator thread. And, it feels to me like
this is quite natural, not just a limitation of the 1.8 implementation.
So, are you sure that elements of the wind list can be shared across
thread, and hence that "running" really needs to be a fluid?
2. Does SRFI-34 (and the R6RS equivalent) fit into your plan at all? I
appreciated the discussion about only being able to implement catch and
throw using call/cc, if the application doesn't also use call/cc -
because I think the problems with implementing SRFI-34 in terms of
catch/throw, or vice versa, are very similar.
Neil
next prev parent reply other threads:[~2010-02-28 22:16 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-14 12:33 catch, throw, prompt, control, fluids, garbage collection Andy Wingo
2010-02-14 14:32 ` Fluids Ludovic Courtès
2010-02-14 15:50 ` Fluids Andy Wingo
2010-02-14 19:09 ` Fluids Ken Raeburn
2010-03-02 23:52 ` Fluids Ludovic Courtès
2010-03-03 12:29 ` Fluids Andy Wingo
2010-03-03 13:09 ` Fluids Ludovic Courtès
2010-03-05 17:24 ` Fluids Ludovic Courtès
2010-02-14 14:45 ` Plan for the next release Ludovic Courtès
2010-02-14 15:54 ` Andy Wingo
2010-02-15 22:07 ` catch, throw, prompt, control, fluids, garbage collection Andy Wingo
2010-02-18 22:35 ` Andy Wingo
2010-02-25 0:00 ` Andy Wingo
2010-02-26 12:27 ` Andy Wingo
2010-02-28 22:16 ` Neil Jerram [this message]
2010-07-17 10:15 ` Andy Wingo
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