[Haskell-cafe] Re: Can't do basic time operations with System.Time

[Simon Marlow]

On 21 January 2005 21:50, John Goerzen wrote:

> On 2005-01-21, Peter Simons <simons at cryp.to> wrote:
>>>                 24 * ((fromIntegral $ tdDay td) +
>>>                       30 * ((fromIntegral $ tdMonth td) +
>>>                             365 * (fromIntegral $ tdYear td)))))
>> 
>> I was wondering: Does this calculation account for leap
>> years? Does it have to?
> 
> I also wondered about all months being 30 days.  But this exact
> algorithm is used in fptools' normalizeTimeDiff, and it seems to work
> out correctly, so I guess the timeDiff functions assume that every
> month has 30 days and every year has 365.

normalizeTimeDiff (and TimeDiff in general) is wrong.  I wouldn't
recommend using it.  There's the TimeExts library in the lang package,
which might be useful to you.

Cheers,
	Simon