On 12/11/10 01:59, Taylor R Campbell wrote:
>    Date: Fri, 10 Dec 2010 17:40:32 -0500
>    From: John Cowan <cowan@mercury.ccil.org>
>
>    I have now added `current-jiffy` for elapsed time.
>
> This doesn't help.  It doesn't give me a TAI clock.  It's also not
> clear to me what good jiffies are instead of seconds, or even how to
> find jiffies on Unix systems.[*]
>
> I recommend a procedure (SECONDS-SINCE-UTC-EPOCH) that returns the
> number of SI seconds that have elapsed since 1972-01-01T00:00:00Z.

This would be good. I've always felt that *local* concepts such as
daily/annual cycles and colour and so on shouldn't be part of the
foundation we build software systems on - not so much that we might one
day write software for aliens, as that we very often write software for
*machines*, that does things like process control; interfacing with
humans occurs at the edge of such systems.

Yes, in a calendar app, you'll need to work with dates. So in general,
you need both date-oriented time and physics-oriented time in a general
purpose computer system. In separate optional modules, so
implementations can provide what they can, and applications can require
what they need.

ABS

--
Alaric Snell-Pym
http://www.snell-pym.org.uk/alaric/

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