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{-# LANGUAGE Safe #-}
-- | TAI and leap-second maps for converting to UTC: most people won't need this module.
module Data.Time.Clock.Internal.AbsoluteTime (
-- TAI arithmetic
AbsoluteTime,
taiEpoch,
addAbsoluteTime,
diffAbsoluteTime,
taiNominalDayStart,
) where
import Control.DeepSeq
import Data.Data
import Data.Time.Calendar.Days
import Data.Time.Clock.Internal.DiffTime
-- | AbsoluteTime is TAI, time as measured by a clock.
newtype AbsoluteTime
= MkAbsoluteTime DiffTime
deriving (Eq, Ord, Data, Typeable)
instance NFData AbsoluteTime where
rnf (MkAbsoluteTime a) = rnf a
-- | The epoch of TAI, which is 1858-11-17 00:00:00 TAI.
taiEpoch :: AbsoluteTime
taiEpoch = MkAbsoluteTime 0
taiNominalDayStart :: Day -> AbsoluteTime
taiNominalDayStart day = MkAbsoluteTime $ realToFrac $ (toModifiedJulianDay day) * 86400
-- | addAbsoluteTime a b = a + b
addAbsoluteTime :: DiffTime -> AbsoluteTime -> AbsoluteTime
addAbsoluteTime t (MkAbsoluteTime a) = MkAbsoluteTime (a + t)
-- | diffAbsoluteTime a b = a - b
diffAbsoluteTime :: AbsoluteTime -> AbsoluteTime -> DiffTime
diffAbsoluteTime (MkAbsoluteTime a) (MkAbsoluteTime b) = a - b
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