[Haskell-cafe] Adding to / subtracting from a LocalTime?

[Roman Cheplyaka]

On Sat, Aug 18, 2012 at 8:27 PM, Adde Nilsson <trialcodr at gmail.com> wrote:

> 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'?
>

The time-lens [1] package should do what you need.

[1]: http://hackage.haskell.org/package/time-lens

Roman
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/haskell-cafe/attachments/20120819/82707712/attachment.htm>