Oops, forgot to attach the code. ---------------------------------------------------------------------------- -- * ClockTime -- | A representation of absolute time, measured as picoseconds since -- the epoch, where the epoch is 1 January 1970 00:10 TAI. newtype ClockTime = ClockTime { ctPicoseconds :: Integer } deriving (Eq, Ord, Num, Enum, Integral, Show, Read) -- | returns the current absolute time getClockTime :: IO ClockTime -- | Difference between two 'ClockTime's newtype TimeDiff = TimeDiff { tdPicoseconds :: Integer } deriving (Eq, Ord, Num, Enum, Integral, Show, Read) -- | An empty 'TimeDiff' noTimeDiff :: TimeDiff -- | Returns the difference between two 'ClockTime's diffClockTimes :: ClockTime -> ClockTime -> TimeDiff -- | Adds a 'TimeDiff' to a 'ClockTime' addToClockTime :: ClockTime -> TimeDiff -> ClockTime {- Rationale: - POSIX's time_t uses a broken notion of "seconds since the epoch", defined by a formula in terms of UTC time ignoring leap seconds. Our ClockTime is defined so as to avoid this brokenness, but it means that a ClockTime cannot trivially be converted to a POSIX time_t. - TimeDiff is now an absolute measure of time period, as compared to the Haskell 98 TimeDiff which was underspecified in this respect. Invariants: t1 `addToClockTime` (t2 `diffClockTimes` t1) == t2 t1 `addToClockTime` noTimeDiff == t1 t1 `diffClockTimes` t1 == noTimeDiff -} ---------------------------------------------------------------------------- -- * CalendarTime data CalendarTime = CalendarTime { ctYear :: Int, ctMonth :: Month, ctDay :: Int, ctHour :: Int, ctMin :: Int, ctSec :: Int, ctPicosec :: Integer, ctTZ :: Timezone } deriving (Eq, Ord, Read, Show) data Timezone -- abstract -- | Make a 'Timezone' -- TODO: do we need to specify daylight savings time too? timezoneFromOffset :: Int -> Timezone timezoneFromName :: String -> Timezone timezoneOffset :: Timezone -> Int timezoneName :: Timezone -> String -- | Convert a 'ClockTime' to a 'CalendarTime' in the current timezone clockTimeToCalendarTime :: ClockTime -> IO CalendarTime -- | Convert a 'ClockTime' to a 'CalendarTime' in UTC clockTimeToUTCTime :: ClockTime -> CalendarTime -- | Convert a 'CalendarTime' to a 'ClockTime'. Some values of -- 'CalendarTime' do not represent a valid 'ClockTime', hence this -- function returns a 'Maybe' type. calendarTimeToClockTime :: CalendarTime -> Maybe ClockTime {- OPTIONAL: these are hard to implement, and require careful specification (see rationale below): addPicoseconds :: CalendarTime -> Integer -> CalendarTime addSeconds :: CalendarTime -> Integer -> CalendarTime addMinutes :: CalendarTime -> Integer -> CalendarTime addDays :: CalendarTime -> Integer -> CalendarTime addWeeks :: CalendarTime -> Integer -> CalendarTime addMonths :: CalendarTime -> Integer -> CalendarTime addYears :: CalendarTime -> Integer -> CalendarTime Rationale: - Adding "irregular" time differences should be done on CalendarTimes, because these operations depend on the timezone. - Need to define the meaning when the offset doesn't exist. eg. adding a day at the end of the month clearly rolls over into the next month. But what about adding a month to January 31st? -}