[commit: packages/time] format-widths, ghc, improve-leapseconds, master, posix-perf, tasty, wip/travis: add dayToCalendar function, with test (266f005)
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Repository : ssh://git@git.haskell.org/time
On branches: format-widths,ghc,improve-leapseconds,master,posix-perf,tasty,wip/travis
Link : http://git.haskell.org/packages/time.git/commitdiff/266f0057ecca2b00449eb0c631c6d9507b8281af
>---------------------------------------------------------------
commit 266f0057ecca2b00449eb0c631c6d9507b8281af
Author: Ashley Yakeley <ashley at semantic.org>
Date: Wed Mar 2 03:12:18 2005 -0800
add dayToCalendar function, with test
darcs-hash:20050302111218-ac6dd-2efd1ae180bcf6b419cbab3f1a1876c5ed7b55c4
>---------------------------------------------------------------
266f0057ecca2b00449eb0c631c6d9507b8281af
System/Time/Calendar.hs | 12 +++++++++++-
TestTime.hs | 6 +++++-
2 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/System/Time/Calendar.hs b/System/Time/Calendar.hs
index fa55f5a..a3b9e5a 100644
--- a/System/Time/Calendar.hs
+++ b/System/Time/Calendar.hs
@@ -7,7 +7,7 @@ module System.Time.Calendar
-- converting times to Gregorian "calendrical" format
TimeOfDay,CalendarDay,CalendarTime,
- dayToCalendar
+ dayToCalendar,calendarToDay
-- calendrical arithmetic
-- e.g. "one month after March 31st"
@@ -102,6 +102,16 @@ dayToCalendar mjd = CalendarDay year month day where
(year,yd,isleap) = dayToYearDay mjd
(month,day) = findMonthDay (months isleap) yd
+-- | find out which day a given Gregorian calendar day is
+calendarToDay :: CalendarDay -> ModJulianDay
+-- formula from <http://en.wikipedia.org/wiki/Julian_Day>
+calendarToDay (CalendarDay year month day) =
+ (fromIntegral day) + (div (153 * m + 2) 5) + (365 * y) + (div y 4) - (div y 100) + (div y 400) - 678882 where
+ month' = fromIntegral month
+ a = div (14 - month') 12
+ y = year - a
+ m = month' + (12 * a) - 3
+
utcToCalendar :: TimeZone -> UTCTime -> CalendarTime
utcToCalendar tz utc = undefined
diff --git a/TestTime.hs b/TestTime.hs
index d724f89..af9ceec 100644
--- a/TestTime.hs
+++ b/TestTime.hs
@@ -5,7 +5,11 @@ import System.Time.TAI
import System.Time.Calendar
showCal :: ModJulianDay -> IO ()
-showCal d = putStrLn ((show d) ++ "=" ++ show (dayToCalendar d))
+showCal d = do
+ let cal = dayToCalendar d
+ let d' = calendarToDay cal
+ putStr ((show d) ++ "=" ++ show (dayToCalendar d))
+ putStrLn (if d == d' then "" else "=" ++ (show d') ++ "!")
for :: (Monad m) => (a -> m ()) -> [a] -> m ()
for _ [] = return ()
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