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

[Marc Feeley <feeley@x>]

On 2010-11-28, at 2:32 PM, John Cowan wrote:

> Marc Feeley scripsit:
> 
>> The problem is that a "date" is just a label for a point in time.
>> A label assigned by humans in a rather arbitrary way that can't
>> even be determined ahead of time (leap seconds, time zones, etc).
> 
> Quite so, which is why I have both instants and date objects.
> 
>> It is quite a shock to think that our "date" labelling system isn't
>> even one-to-one with time points (for example, on the US east coast,
>> there are two points in time that correspond to 1:30 AM November 7,
>> 2010, because at 2 AM November 7, 2010 the clocks are set back to 1
>> AM to return to Standard Time).
> 
> Hence the existence of the daylight-savings-time field and its C analogue,
> the dstflag.
> 
>> I want to make sure that the date and time abstractions are not
>> hopelessly intertwined.  The thread/process scheduler of an OS should
>> work with time points.  A calendar application should work with dates.
> 
> Correct.  And it's a calendar API I'm proposing.

Thank you for clarifying your intentions.

Marc


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