Messing around with the haskell thyme package.

AffineTime.hs

import Data.Thyme hiding (seconds)
import Data.Thyme.Format.Human
import Data.AffineSpace
import Data.VectorSpace

seconds, minutes, hours, days, weeks :: Rational -> NominalDiffTime
seconds n = fromSeconds n
minutes n = n *^ 60 *^ seconds 1
hours   n = n *^ 60 *^ minutes 1
days    n = n *^ 24 *^ hours 1
weeks   n = n *^  7 *^ days 1

now, xmas, dec, t0, helio :: UTCTime
now   = read "2013-08-10 08:52:13 EST"
xmas  = read "2013-12-25 06:00:00 EST"
dec   = read "2010-01-01 00:00:00 EST"
t0    = read "1977-09-05 12:56:00 UTC"
helio = read "2012-08-25 00:00:00 UTC"

announce str d = putStrLn $ "Time to " ++ str ++ ": " ++ humanTimeDiff d

main = do
  announce "leave the solar system" $ helio .-. t0
  announce "wait for presents"      $ xmas .-. now

  print . toSeconds $ (helio .-. t0) ^/ toSeconds (xmas .-. now)
  print (now .+^ weeks 3 .+^ days 2)