Time Libraries Rough Draft

[Ashley Yakeley]

In article <20050212150528.GH4062 at momenergy.repetae.net>,
 John Meacham <john at repetae.net> wrote:

> which will do its best to get the current TAI time (subject to system
> interfaces). which may be just converting from POSIX time with the most
> up-to-date leap second table, but very well might do something better on
> some systems.

Doing this sort of "whatever's best" has problems. We have to provide a 
single library that people will compile in to their programs, and a 
single binary may run on systems with different resources available.

I'd rather give users the tools they need to get the table or to get TAI 
in explicit ways, rather than doing a bunch of unknown stuff such as 
file access behind the scenes. This way people can come up with their 
own strategies for the kind of reliability they need. Something like 
this, perhaps:

  parseLeapSecondTableFromUSNO :: ReadS LeapSecondTable  

  parseLeapSecondTableFromLibTAI :: ReadS LeapSecondTable

  getLeapSecondTableFromLibTAI :: FilePath -> IO LeapSecondTable

-- 
Ashley Yakeley, Seattle WA