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From: Andy Wingo <wingo@pobox.com>
To: guile-devel <guile-devel@gnu.org>
Subject: truth of %nil
Date: Mon, 29 Jun 2009 23:12:11 +0200	[thread overview]
Message-ID: <m33a9izqvo.fsf@pobox.com> (raw)

Hi all,

Daniel came up with an interesting test case:

    scheme@(guile-user)> (if %nil 1 2)
    1

We could fix this transparently by changing scm_is_false in boolean.h
from:

    #define scm_is_false(x) scm_is_eq ((x), SCM_BOOL_F)

to

    #define scm_is_false(x) (scm_is_eq ((x), SCM_BOOL_F) || SCM_NILP (x))

I'm not really sure if this is the right place for this to go, though.
It seems that it is. (Ideally the two values would differ by one bit
only, and we could mask that bit away and just have the one test.) What
do people think?

Andy
-- 
http://wingolog.org/




             reply	other threads:[~2009-06-29 21:12 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-29 21:12 Andy Wingo [this message]
2009-06-29 21:44 ` truth of %nil Neil Jerram
2009-06-29 22:11   ` Andy Wingo
2009-06-30 22:22     ` Neil Jerram
2009-07-01  6:45       ` Daniel Kraft
2009-07-01 21:54         ` Neil Jerram
2009-07-05 13:07           ` Mark H Weaver
2009-08-30 11:07             ` Neil Jerram
2009-08-30 14:11               ` Mark H Weaver
2009-09-01 22:00                 ` Neil Jerram
2009-09-02 15:57                   ` Mark H Weaver
2009-09-17 21:21                     ` Neil Jerram
2009-07-02 14:28   ` Mark H Weaver
2009-07-02 14:50     ` Ludovic Courtès
2009-07-02 22:50     ` Neil Jerram
2009-07-03 15:32       ` Mark H Weaver
2009-07-05  2:41         ` Mark H Weaver
2009-07-05  9:19           ` Andy Wingo
2009-07-07 11:14             ` Mark H Weaver
2009-07-08 13:17               ` Mark H. Weaver
2009-08-30 11:20                 ` Neil Jerram
2009-08-30 11:13               ` Neil Jerram
2009-08-30 14:15                 ` Mark H Weaver
2009-09-01 21:50                   ` Neil Jerram
2009-08-30 22:01                 ` Ken Raeburn
2009-08-31 21:59                   ` Ludovic Courtès
2009-08-31 23:39                     ` Ken Raeburn
2009-08-31 21:55                 ` SCM_BOOL_F == 0 and BDW-GC Ludovic Courtès
2009-09-17 22:00                   ` Neil Jerram
2009-09-17 22:28                     ` Ludovic Courtès
2009-09-18 20:51                       ` Neil Jerram
2009-09-20 17:21                         ` Ludovic Courtès
2009-09-20 21:03                           ` Neil Jerram
2009-09-20 21:36                             ` Ludovic Courtès
2009-07-06 21:46           ` truth of %nil Neil Jerram
2009-07-06 23:54             ` Mark H Weaver
2009-07-08  8:08             ` Ludovic Courtès
2009-07-23 21:12         ` Andy Wingo

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