| Safe Haskell | Safe-Inferred |
|---|---|
| Language | Haskell2010 |
Data.Thyme.Clock.TAI
Contents
Description
International Atomic Time (TAI) and conversion to/from UTC, accounting for leap seconds.
Synopsis
- data AbsoluteTime
- taiEpoch :: AbsoluteTime
- data TAIUTCMap = TAIUTCMap (Map UTCTime TAIUTCRow) (Map AbsoluteTime TAIUTCRow)
- data TAIUTCRow = TAIUTCRow !DiffTime !UTCTime !Rational
- absoluteTime :: TAIUTCMap -> Iso' UTCTime AbsoluteTime
- absoluteTime' :: TAIUTCMap -> Iso' UTCView AbsoluteTime
- utcDayLength :: TAIUTCMap -> Day -> DiffTime
- parseTAIUTCRow :: Parser (UTCTime, TAIUTCRow)
- makeTAIUTCMap :: [(UTCTime, TAIUTCRow)] -> TAIUTCMap
- parseTAIUTCDAT :: ByteString -> Either String TAIUTCMap
- addAbsoluteTime :: DiffTime -> AbsoluteTime -> AbsoluteTime
- diffAbsoluteTime :: AbsoluteTime -> AbsoluteTime -> DiffTime
- utcToTAITime :: TAIUTCMap -> UTCTime -> AbsoluteTime
- taiToUTCTime :: TAIUTCMap -> AbsoluteTime -> UTCTime
Documentation
data AbsoluteTime Source #
Temps Atomique International
(TAI). Note that for most applications UTCTime is perfectly sufficient,
and much more convenient to use.
Internally this is the number of seconds since taiEpoch. TAI days are
exactly 86400 SI seconds long.
Instances
taiEpoch :: AbsoluteTime Source #
The Modified Julian Day epoch, which is 1858-11-17 00:00:00 TAI.
A table of TAIUTCRows for converting between TAI and UTC.
The two Maps are keyed on the corresponding instants in UTC and TAI
from which the TAIUTCRow becomes applicable. The UTCTime key of the
first Map is always at midnight.
No table is provided here because leap seconds are unpredictable, and any
program shipped with such a table could become out-of-date in as little
as 6 months. See parseTAIUTCDAT for details.
Instances
| Data TAIUTCMap Source # | |
Defined in Data.Thyme.Clock.TAI Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> TAIUTCMap -> c TAIUTCMap # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c TAIUTCMap # toConstr :: TAIUTCMap -> Constr # dataTypeOf :: TAIUTCMap -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c TAIUTCMap) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TAIUTCMap) # gmapT :: (forall b. Data b => b -> b) -> TAIUTCMap -> TAIUTCMap # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> TAIUTCMap -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> TAIUTCMap -> r # gmapQ :: (forall d. Data d => d -> u) -> TAIUTCMap -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> TAIUTCMap -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> TAIUTCMap -> m TAIUTCMap # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> TAIUTCMap -> m TAIUTCMap # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> TAIUTCMap -> m TAIUTCMap # | |
| Generic TAIUTCMap Source # | |
| Show TAIUTCMap Source # | |
| Eq TAIUTCMap Source # | |
| Ord TAIUTCMap Source # | |
| type Rep TAIUTCMap Source # | |
Defined in Data.Thyme.Clock.TAI type Rep TAIUTCMap = D1 ('MetaData "TAIUTCMap" "Data.Thyme.Clock.TAI" "thyme-0.4-HyK6SfK4MlBKX4LjgMsZJ4" 'False) (C1 ('MetaCons "TAIUTCMap" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Map UTCTime TAIUTCRow)) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Map AbsoluteTime TAIUTCRow)))) | |
Each line of tai-utc.dat (see parseTAIUTCDAT) specifies the difference
between TAI and UTC for a particular period. For example:
1968 FEB 1 =JD 2439887.5 TAI-UTC= 4.2131700 S + (MJD - 39126.) X 0.002592 S
says that from 1968-02-01 00:00:00 (Julian Date 2439887.5; or Modified
Julian Date 39887.0), the difference between TAI and UTC is 4.2131700s
(the additive part) plus a scaled component that increases for each day
beyond MJD 39126 (the base) by 0.002592s (the coefficient). In
general, the latter half of each line is of the form:
TAI-UTC= additive S + (MJD - base) X coefficient S
TAIUTCRow a b cUTCTime—seconds since
the MJD epoch—as the MJD term without further rescaling.
Note that between 1961-01-01 and 1972-01-01, each UTC second was actually slightly longer than one TAI (or SI) second. For the first year this was at the rate of exactly 1.000000015 TAI (or SI) seconds per UTC second, but was subject to irregular updates. Since leap seconds came into effect on 1972-01-01, the additive part has always been an intergral number of seconds, and the coefficient has always been zero.
To convert between TAI and UTC, we refer to the definition:
TAI - UTC = a + (MJD - b) * c
Using UTC for MJD (with b and c scaled as described above):
TAI = UTC + a + (UTC - b) * c TAI - a + b * c = UTC + UTC * c (TAI - a + b * c) / (1 + c) = UTC
This is implemented by absoluteTime and absoluteTime'.
Further reading:
Constructors
| TAIUTCRow !DiffTime !UTCTime !Rational | Each row comprises of an additive component, the base of the scaled component, and the coefficient of the scaled component. |
Instances
| Data TAIUTCRow Source # | |
Defined in Data.Thyme.Clock.TAI Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> TAIUTCRow -> c TAIUTCRow # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c TAIUTCRow # toConstr :: TAIUTCRow -> Constr # dataTypeOf :: TAIUTCRow -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c TAIUTCRow) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c TAIUTCRow) # gmapT :: (forall b. Data b => b -> b) -> TAIUTCRow -> TAIUTCRow # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> TAIUTCRow -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> TAIUTCRow -> r # gmapQ :: (forall d. Data d => d -> u) -> TAIUTCRow -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> TAIUTCRow -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> TAIUTCRow -> m TAIUTCRow # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> TAIUTCRow -> m TAIUTCRow # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> TAIUTCRow -> m TAIUTCRow # | |
| Generic TAIUTCRow Source # | |
| Show TAIUTCRow Source # | |
| Eq TAIUTCRow Source # | |
| Ord TAIUTCRow Source # | |
| type Rep TAIUTCRow Source # | |
Defined in Data.Thyme.Clock.TAI type Rep TAIUTCRow = D1 ('MetaData "TAIUTCRow" "Data.Thyme.Clock.TAI" "thyme-0.4-HyK6SfK4MlBKX4LjgMsZJ4" 'False) (C1 ('MetaCons "TAIUTCRow" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 DiffTime) :*: (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 UTCTime) :*: S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'SourceStrict 'DecidedStrict) (Rec0 Rational)))) | |
absoluteTime :: TAIUTCMap -> Iso' UTCTime AbsoluteTime Source #
Convert between UTCTime and AbsoluteTime using a TAIUTCMap.
Since UTCTime cannot represent a time-of-day of 86400s or more, any
conversion from AbsoluteTime that happens to be during a leap second
will overflow into the next day.
See parseTAIUTCDAT for how to obtain the tum :: below.TAIUTCMap
> let jul1 =utcTime#UTCView(gregorian#YearMonthDay2015 7 1)zeroV> jul1&absoluteTimetum%~(.-^fromSeconds1.1) 2015-06-30 23:59:59.9 UTC
absoluteTime' :: TAIUTCMap -> Iso' UTCView AbsoluteTime Source #
Convert between UTCView and TAI AbsoluteTime using a TAIUTCMap.
Unlike absoluteTime, UTCView can represent a time-of-day greater
than 86400s, and this gives the correct results during a leap second.
See parseTAIUTCDAT for how to obtain the tum :: below.TAIUTCMap
> let jul1 =UTCView(gregorian#YearMonthDay2015 7 1)zeroV> jul1&absoluteTime'tum%~(.-^fromSeconds0.1)UTCView{utcvDay= 2015-06-30,utcvDayTime= 86400.9s}
However keep in mind that currently there is no standard way to get the
TAI on most platforms. Simply converting the result of
getCurrentTime (which calls gettimeofday(2)) to
AbsoluteTime during a leap second will still give non-monotonic times.
utcDayLength :: TAIUTCMap -> Day -> DiffTime Source #
Using a TAIUTCMap, lookup the DiffTime length of the UTC Day.
See parseTAIUTCDAT for how to obtain the tum :: below.TAIUTCMap
>utcDayLengthtum.view_utctDay<$>getCurrentTime86400s >utcDayLengthtum$gregorian#YearMonthDay2015 6 30 86401s
parseTAIUTCRow :: Parser (UTCTime, TAIUTCRow) Source #
attoparsec Parser for a single line of tai-utc.dat.
makeTAIUTCMap :: [(UTCTime, TAIUTCRow)] -> TAIUTCMap Source #
Build a TAIUTCMap from the result of parseTAIUTCRow.
Compatibility
addAbsoluteTime :: DiffTime -> AbsoluteTime -> AbsoluteTime Source #
Add a duration to an AbsoluteTime.
addAbsoluteTime=flip(.+^)addAbsoluteTimed t ≡ t.+^d
See also the AffineSpace instance for AbsoluteTime.
diffAbsoluteTime :: AbsoluteTime -> AbsoluteTime -> DiffTime Source #
The duration difference between two AbsoluteTimes.
diffAbsoluteTime= (.-.)diffAbsoluteTimea b ≡ a.-.b
See also the AffineSpace instance for AbsoluteTime.
utcToTAITime :: TAIUTCMap -> UTCTime -> AbsoluteTime Source #
Using a TAIUTCMap, convert a UTCTime to AbsoluteTime.
utcToTAITime=view.absoluteTime
taiToUTCTime :: TAIUTCMap -> AbsoluteTime -> UTCTime Source #
Using a TAIUTCMap, convert a AbsoluteTime to UTCTime.
taiToUTCTime=review.absoluteTime