From: ludo@gnu.org (Ludovic Courtès)
To: guile-devel@gnu.org
Subject: Re: when and unless
Date: Wed, 07 Dec 2011 15:19:58 +0100 [thread overview]
Message-ID: <87ehwg5ur5.fsf@gnu.org> (raw)
In-Reply-To: 87d3c1lq6i.fsf@gnu.org
Hi,
ludo@gnu.org (Ludovic Courtès) skribis:
> Andy Wingo <wingo@pobox.com> skribis:
>
>> On Thu 30 Jun 2011 12:44, Andy Wingo <wingo@pobox.com> writes:
>>
>>> I think we should add `when' and `unless' to the default environment.
>>>
>>> They go like this:
>>>
>>> (define-syntax when
>>> (syntax-rules ()
>>> ((_ test then then* ...)
>>> (if test (begin then then* ... (if #f #f))))))
>>>
>>> (define-syntax unless
>>> (syntax-rules ()
>>> ((_ test else else* ...)
>>> (if (not test) (begin else else* ... (if #f #f))))))
>>
>> WDYT? `unless' is nice for assertions, `when' is its converse, and most
>> Schemes have them. I would like to add them to Guile too.
>
> Yes, feel free.
Like Marijn, it seems more natural for me to return the values of the
body’s last expression, rather than *unspecified*.
Thanks,
Ludo’.
next prev parent reply other threads:[~2011-12-07 14:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-30 10:44 when and unless Andy Wingo
2011-06-30 21:46 ` Ludovic Courtès
2011-07-01 7:50 ` Andy Wingo
2011-07-01 12:47 ` Ludovic Courtès
2011-12-05 20:23 ` Andy Wingo
2011-12-06 7:48 ` Marijn
2011-12-06 8:29 ` Alex Shinn
2011-12-06 11:17 ` David Kastrup
2011-12-06 16:25 ` Andy Wingo
2011-12-06 16:42 ` David Kastrup
2011-12-06 17:35 ` Andy Wingo
2011-12-06 22:08 ` David Kastrup
2011-12-06 23:05 ` Chris K. Jester-Young
2011-12-07 9:23 ` David Kastrup
2011-12-07 15:58 ` Chris K. Jester-Young
2011-12-08 8:42 ` David Kastrup
2011-12-08 15:34 ` Chris K. Jester-Young
2011-12-08 16:10 ` David Kastrup
2011-12-08 18:10 ` Ian Price
2011-12-07 16:10 ` Chris K. Jester-Young
2011-12-06 19:05 ` Chris K. Jester-Young
2011-12-06 19:33 ` Andy Wingo
2011-12-06 14:39 ` Ludovic Courtès
2011-12-07 14:19 ` Ludovic Courtès [this message]
2011-12-07 14:27 ` David Kastrup
2012-01-07 0:16 ` Andy Wingo
2012-01-07 22:36 ` Ludovic Courtès
2012-01-20 20:19 ` Andy Wingo
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