Time Libraries Rough Draft

[Seth Kurtzberg]

Ashley Yakeley wrote:

>In article <87k6pgacrj.fsf at sefirot.ii.uib.no>,
> Ketil Malde <ketil+haskell at ii.uib.no> wrote:
>
>  
>
>>>  * UTC arithmetic
>>>  * types or type-synonyms for Julian days and dates (for UT1)
>>>  * getting the current UTC time
>>>      
>>>
>>(I'd call these -- anything that maps SI seconds to other structures,
>>really -- calendars, but I guess I've said so enough times already :-)
>>    
>>
>
>I see a calendar as something that maps UTCTime to other structures.
>  
>
I still think a calendar only makes sense mapping TAI time to other 
structures, including UTC time.  There really are good reasons that 
other systems have implemented it this way.  The bias should be towards 
implementing the structures in the way that those who have studied the 
problem at great length have concluded.  UTC time itself may, or may 
not, in any given instant, be corrected at those times when correction 
is needed.  The simple fact that UTC time is not monotonically 
increasing causes a whole host of difficulties.  I see no advantage to 
not only reinventing this wheel, but in using a different wheel.