lib/Data/Time/Clock/POSIX.hs

    -- | POSIX time, if you need to deal with timestamps and the like.
    -- Most people won't need this module.
    --
    -- You can use 'POSIXTime' to obtain integer/word timestamps. For example:
    --
    -- > import Data.Time
    -- > import Data.Time.Clock.POSIX
    -- > import Data.Int
    -- >
    -- > nanosSinceEpoch :: UTCTime -> Int64
    -- > nanosSinceEpoch =
    -- >     floor . (1e9 *) . nominalDiffTimeToSeconds . utcTimeToPOSIXSeconds
    -- >
    -- > main :: IO ()
    -- > main = do
    -- >     u <- getCurrentTime
    -- >     print $ nanosSinceEpoch u
    module Data.Time.Clock.POSIX
    (
        posixDayLength,POSIXTime,posixSecondsToUTCTime,utcTimeToPOSIXSeconds,getPOSIXTime,getCurrentTime,
        systemToPOSIXTime,
    ) where

    import Data.Time.Clock.Internal.POSIXTime
    import Data.Time.Clock.Internal.UTCTime
    import Data.Time.Clock.System
    import Data.Time.Calendar.Days
    import Data.Fixed

    posixSecondsToUTCTime :: POSIXTime -> UTCTime
    posixSecondsToUTCTime i = let
        (d,t) = divMod' i posixDayLength
     in UTCTime (addDays d systemEpochDay) (realToFrac t)

    utcTimeToPOSIXSeconds :: UTCTime -> POSIXTime
    utcTimeToPOSIXSeconds (UTCTime d t) =
     (fromInteger (diffDays d systemEpochDay) * posixDayLength) + min posixDayLength (realToFrac t)

    systemToPOSIXTime :: SystemTime -> POSIXTime
    systemToPOSIXTime (MkSystemTime s ns) = (fromIntegral s) + (fromIntegral ns) * 1E-9

    -- | Get the current POSIX time from the system clock.
    getPOSIXTime :: IO POSIXTime
    getPOSIXTime = fmap systemToPOSIXTime getSystemTime

    -- | Get the current 'UTCTime' from the system clock.
    getCurrentTime :: IO UTCTime
    getCurrentTime = systemToUTCTime `fmap` getSystemTime