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{-# LANGUAGE Safe #-}
-- | 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.Fixed
import Data.Time.Calendar.Days
import Data.Time.Clock.Internal.POSIXTime
import Data.Time.Clock.Internal.UTCTime
import Data.Time.Clock.System
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
|
