In article <20050705230703.GA26379@momenergy.repetae.net>,
John Meacham
It needs a getTAItime :: IO AbsoluteTime and a getLeapSecondTable :: IO LeapSecondTable
Many systems have ways to get at these and it would be a travesty if we didn't fix this hole in the API when we have the chance. As always, the library should make its best effort to get at this info. ...
How do I implement these?
Also, it would be nice if the LeapSecondTable was not a functional type, but rather something with structure, like a list of (year,offset) pairs. There could be apps that will have to look at which years the leap seconds actually occured in and probing the function with every possible value in its domain is not very fun.
That's a good question. I used a function because that's the "least" type necessary to do the conversions, at the same time allowing estimates extending infinitely into the future (and past, if we want "proleptic UTC"). A list of pairs would have to be walked through, in effect converted to the function type.
Also, shouldn't AbsoluteTime be an instance of several Num classes?
No, I don't think any Num functions apply. There's no "zero time" and you can't meaningfully add 3am today to 7pm tomorrow.
What units does DiffTime have?
Seconds, and I'll add that to the doc.
is it relative, or is the length of a DiffTime independent of what you do to it?
A DiffTime is always real absolute seconds such as a good clock might measure, independent of whatever the earth might be doing. -- Ashley Yakeley, Seattle WA