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Re: when and unless
From: |
Andy Wingo |
Subject: |
Re: when and unless |
Date: |
Sat, 07 Jan 2012 01:16:02 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.3 (gnu/linux) |
Hi,
On Wed 07 Dec 2011 15:19, address@hidden (Ludovic Courtès) writes:
>>> On Thu 30 Jun 2011 12:44, Andy Wingo <address@hidden> writes:
>>>
>>>> I think we should add `when' and `unless' to the default environment.
>
> Like Marijn, it seems more natural for me to return the values of the
> body’s last expression, rather than *unspecified*.
Given that there are reasonable cases for `when' and `unless' in
side-effecting loops, it is indeed probably best to preserve the
<tail sequence> nature of the body of these forms.
Are you OK with adding them like this:
(define-syntax (when condition stmt stmt* ...)
(if condition (begin stmt stmt* ...)))
(define-syntax (unless condition stmt stmt* ...)
(if (not condition) (begin stmt stmt* ...)))
Andy
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- Re: when and unless,
Andy Wingo <=