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Re: What are the arguments in favor of delay/force in eval.c?

From: Rob Browning
Subject: Re: What are the arguments in favor of delay/force in eval.c?
Date: Fri, 09 Dec 2005 20:23:53 -0800
User-agent: Gnus/5.110004 (No Gnus v0.4) Emacs/21.4 (gnu/linux)

Kevin Ryde <address@hidden> writes:

>> I was also wondering about the possibilities for deadlock with the
>> current code, and then what they might be with a srfi-45 force,
> Whenever arbitrary code executes in a mutex I guess there's scope for
> that.  srfi-45 shouldn't be inherently worse.

I'm not sure either way yet.  There are subtleties of srfi-45 that I
still don't fully understand.  If you haven't already, check out the
reference implementation of force, and then the test cases.

I'll probably have to wait until I feel like I understand the detailed
semantics better before I can comment much.

> Second block of code is with two magic "uncomputed" values, one for
> normal and one for srfi-45 style lazy promises.  If I understand how
> they're supposed to work :-).

You may have already noticed this, but I think the semantics of
SRFI-45 force/delay are supposed to be a strict superset of R5RS
force/delay, so in theory we might be able to have just one type of

Rob Browning
rlb and; previously
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