[pro] (values) for for-effect functions

[Peter Seibel]

You mean PCL the CLOS implementation, right?

-Peter

On Tue, Dec 7, 2010 at 10:20 AM, Pascal Costanza <pc at p-cos.net> wrote:
>
> On 3 Dec 2010, at 13:34, Martin Simmons wrote:
>
>> I think it is confusing to use (values) for that purpose, because "no values"
>> is also a valid return value (e.g. for reader macro functions
>> http://www.lispworks.com/documentation/HyperSpec/Body/02_add.htm).
>>
>> I would make it a macro, called something like void.
>>
>> OTOH, use of (values) or (void) will prevent tail call optimization, so may be
>> undesirable.
>
> I think this is the strongest argument in this thread: Most other arguments seem to point out only subjective and/or stylistic issues, while this one is a hard technical difference. Preventing tail call optimizations for stylistic issues is a bad idea, IMHO.
>
> I have occasionally used the (values) idiom, but only in test situations, when I don't like seeing return values in the REPL. I seem to recall some uses of (values) in PCL.
>
> Pascal
>
> --
> Pascal Costanza, mailto:pc at p-cos.net, http://p-cos.net
> Vrije Universiteit Brussel
> Software Languages Lab
> Pleinlaan 2, B-1050 Brussel, Belgium
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-- 
Peter Seibel
http://www.codequarterly.com/