Re: [Scheme-reports] [r6rs-discuss] Date and time arithmetic library proposal for R7RS large Scheme

[John Cowan <cowan@x>]

Thomas Bushnell, BSG scripsit:

> The time functions should return a NUMBER. I'm disgusted (sorry) with the
> retreat from Scheme's excellent numeric system. Implementations can return
> whichever format number suits them best. Let the interface declare the
> accuracy of the returned value as well--as a number.

Nobody disputes that the representation of an instant of time should be
a number, and a rational number at that.  But instants aren't sufficient
for dealing with all cases of time.  Back in the middle Devonian, an
instant (whether second or millisecond) is much too precise -- indeed,
a day is much too precise, as we know only roughly how many days per year
there were then.  Less exotically, a government bond might fall due on
"March 31, 2031, 5 P.M. Washington D.C. time".  What instant is that?
We don't know, because Congress might change the rules for Daylight
Saving Time again.

So there has to be a way of representing and dealing with broken-out
dates and times, since those are what matter in the Real World.

-- 
The man that wanders far                        cowan@x
from the walking tree                           http://www.ccil.org/~cowan
        --first line of a non-existent poem by:         John Cowan

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