Ok, do you know of any way to add/subtract without converting to UTC and back? On Sat, Aug 18, 2012 at 7:53 PM, Paolino wrote:

Hello.

This is a part of a solution, with explicit TimeZone

Prelude Data.Time> :t \z s t -> utcToLocalTime z $ addUTCTime (fromIntegral s) (localTimeToUTC z t) \z s t -> utcToLocalTime z $ addUTCTime (fromIntegral s) (localTimeToUTC z t) :: Integral a => TimeZone -> a -> LocalTime -> LocalTime

where the Integral arguments is in seconds, by docs

regards paolino

2012/8/18 Adde Nilsson

...

Hi. How do you add to or subtract from a LocalTime? I'm trying to subtract a second from a LocalTime value but the only API's I can find act only on the TimeOfDay part.

subSec :: LocalTime -> LocalTime subSec (LocalTime d t) = LocalTime d $ timeToTimeOfDay ((timeOfDayToTime t) - (secondsToDiffTime 1))

I'm obviously on the wrong track as this looks way too complex for what it's trying to achieve. Calling with '2012-08-18 00:00:00' gives '2012-08-18 -01:59:59' which isn't very helpful. How do I get to '2012-08-17 23:59:59'?

Thanks, Adde

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Didn't know, thanks. Back in Haskell land my conclusion is that if you're planning on doing pure date calculations you have to pass a TimeZone as well. /Adde On Sun, Aug 19, 2012 at 12:11 AM, Brandon Allbery wrote:

On Sat, Aug 18, 2012 at 6:05 PM, Adde Nilsson wrote:

...

Ok, do you know of any way to add/subtract without converting to UTC and back?

I'm not sure I'd do that in any environment, since usually libraries don't deal with the result crossing a daylight/summer time change (and those that do, surprise surprise, normalize to UTC).

-- brandon s allbery allbery.b@gmail.com wandering unix systems administrator (available) (412) 475-9364 vm/sms