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Re: when and unless
From: |
Ludovic Courtès |
Subject: |
Re: when and unless |
Date: |
Wed, 07 Dec 2011 15:19:58 +0100 |
User-agent: |
Gnus/5.110018 (No Gnus v0.18) Emacs/24.0.90 (gnu/linux) |
Hi,
address@hidden (Ludovic Courtès) skribis:
> Andy Wingo <address@hidden> skribis:
>
>> On Thu 30 Jun 2011 12:44, Andy Wingo <address@hidden> 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’.
- Re: when and unless, (continued)
- Re: when and unless, David Kastrup, 2011/12/07
- Re: when and unless, Chris K. Jester-Young, 2011/12/07
- Re: when and unless, David Kastrup, 2011/12/08
- Re: when and unless, Chris K. Jester-Young, 2011/12/08
- Re: when and unless, David Kastrup, 2011/12/08
- Re: when and unless, Ian Price, 2011/12/08
- Re: when and unless, Chris K. Jester-Young, 2011/12/07
Re: when and unless, Chris K. Jester-Young, 2011/12/06
Re: when and unless, Ludovic Courtès, 2011/12/06
- Re: when and unless,
Ludovic Courtès <=