GNU bug report logs - #24102
Use guile variable objects as SRFI-111 boxes.

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Message #19 received at 24102 <at> debbugs.gnu.org (full text, mbox):

From: Mark H Weaver <mhw <at> netris.org>
To: "Glenn Michaels" <gmichaels <at> Safe-mail.net>
Cc: Andy Wingo <wingo <at> pobox.com>, 24102 <at> debbugs.gnu.org
Subject: Re: bug#24102: Use guile variable objects as SRFI-111 boxes.
Date: Fri, 05 Aug 2016 00:37:40 -0400

Mark H Weaver <mhw <at> netris.org> writes:

> As a result, some important properties of SRFI-111 boxes do not hold for
> your proposed implementation.  For example, in SRFI-111, (box? x)
> implies that (box-ref x) will not raise an exception, and this fact can
> be exploited by a compiler to produce better native code for 'box-ref'
> when the type of its argument is known to be a box.  In such cases, I
> guess 'box-ref' can be implemented as a single load instruction, whereas
> 'variable-ref' will require a conditional branch.

s/box-ref/unbox/g

     Mark

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