module Time(Time(..), dblToTime, timeToDbl, timeToString) where -- year mon day hour min sec ... wday data Time = Time Int Int Int Int Int Int Double Int deriving (Eq, Ord, Text) isleap :: Int -> Bool isleap n = n `rem` 4 == 0 -- good enough for the UNIX time span daysin :: Int -> Int daysin n = if isleap n then 366 else 365 monthlen :: Array (Bool, Int) Int monthlen = array ((False, 1), (True, 12)) (zipWith3 (\ a b c -> (a,b):=c) (repeat False) [1..] [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] ++ zipWith3 (\ a b c -> (a,b):=c) (repeat True) [1..] [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]) -- Time zone offset in minutes tzOffset = 120 -- Swedish DST dblToTime :: Double -> Time dblToTime d = let t = truncate d :: Int offset = tzOffset -- timezone (days, rem) = (t+offset*60) `quotRem` (60*60*24) (hour, rem') = rem `quotRem` (60*60) (min, sec) = rem' `quotRem` 60 wday = (days+3) `mod` 7 (year, days')= until (\ (y, d) -> d < daysin y) (\ (y, d) -> (y+1, d - daysin y)) (1970, days) (mon, day) = until (\ (m, d) -> d <= monthlen!(isleap year, m)) (\ (m, d) -> (m+1, d - monthlen!(isleap year, m))) (1, days') in Time year mon (day+1) hour min sec (d - fromInt t) wday timeToDbl :: Time -> Double timeToDbl (Time year mon day hour min sec sdec _) = let year' = year - 1970 offset = tzOffset -- timezone days = year' * 365 + (year'+1) `div` 4 + sum [monthlen!(isleap year, m) | m<-[1..mon-1]] + day - 1 secs = ((days*24 + hour) * 60 + min - offset) * 60 + sec in fromInt secs + sdec show2 :: Int -> String show2 x = [chr (x `quot` 10 + ord '0'), chr (x `rem` 10 + ord '0')] weekdays = ["Mon","Tue","Wen","Thu","Fri","Sat","Sun"] timeToString :: Time -> String timeToString (Time year mon day hour min sec sdec wday) = show year ++ "-" ++ show2 mon ++ "-" ++ show2 day ++ " " ++ show2 hour ++ ":" ++ show2 min ++ ":" ++ show2 sec ++ tail (take 5 (show sdec)) ++ " " ++ weekdays!!wday -- For those of you who don't have fromInt fromInt = fromInteger . toInteger