How can I extract specific time components out of a UTCTime?

Question

If I have this code:

let time = read "2013-02-03 17:00:07.687" :: UTCTime

How can I extract the minutes and seconds components out of the UTCTime?

Answer 1

A UTCTime has two components: a day and a DiffTime. You can get the DiffTime using utctDayTime or by pattern matching. From there, you can convert it to a TimeOfDay using timeToTimeOfDay. You can then just pattern match against the TimeOfDay to get the hours, minutes and seconds.

So you could do this:

let TimeOfDay hours minutes seconds = timeToTimeOfDay (utctDayTime time)

You can also use the todMin and todSec functions to get the minutes and seconds respectively out of the TimeOfDay.

Answer 2

You can use the time-lens package, which makes time and date manipulation much easier. E.g.

> let time = read "2013-02-03 17:00:07.687" :: UTCTime
> getL seconds time
7.687000000000

If you import Data.Lens.Common, there's also an infix version of getL:

> time ^. minutes
0