1 module Time(Time(..), dblToTime, timeToDbl, timeToString) where
2 -- year mon day hour min sec ... wday
3 data Time = Time Int Int Int Int Int Int Double Int deriving (Eq, Ord, Text)
6 isleap n = n `rem` 4 == 0 -- good enough for the UNIX time span
9 daysin n = if isleap n then 366 else 365
11 monthlen :: Array (Bool, Int) Int
13 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] ++
14 zipWith3 (\ a b c -> (a,b):=c) (repeat True) [1..] [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31])
16 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] ++
17 zipWith3 (\ a b c -> ((a,b),c)) (repeat True) [1..] [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31])
20 dblToTime :: Double -> Time
22 let t = truncate d :: Int
23 (days, rem) = t `quotRem` (60*60*24)
24 (hour, rem') = rem `quotRem` (60*60)
25 (min, sec) = rem' `quotRem` 60
26 wday = (days+3) `mod` 7
27 (year, days')= until (\ (y, d) -> d < daysin y) (\ (y, d) -> (y+1, d - daysin y)) (1970, days)
28 (mon, day) = until (\ (m, d) -> d < monthlen!(isleap year, m)) (\ (m, d) -> (m+1, d - monthlen!(isleap year, m))) (1, days')
29 in Time year mon (day+1) hour min sec (d - fromInt t) wday
31 timeToDbl :: Time -> Double
32 timeToDbl (Time year mon day hour min sec sdec _) =
33 let year' = year - 1970
34 days = year' * 365 + (year'+1) `div` 4 +
35 sum [monthlen!(isleap year, m) | m<-[1..mon-1]] + day - 1
36 secs = ((days*24 + hour) * 60 + min) * 60 + sec
37 in fromInt secs + sdec
39 show2 :: Int -> String
40 show2 x = [chr (x `quot` 10 + ord '0'), chr (x `rem` 10 + ord '0')]
42 weekdays = ["Mon","Tue","Wed","Thu","Fri","Sat","Sun"]
44 timeToString :: Time -> String
45 timeToString (Time year mon day hour min sec sdec wday) =
46 show year ++ "-" ++ show2 mon ++ "-" ++ show2 day ++ " " ++
47 show2 hour ++ ":" ++ show2 min ++ ":" ++ show2 sec ++
48 tail (take 5 (show sdec)) ++ " " ++ weekdays!!wday
50 #if defined(__YALE_HASKELL__)
51 -- For those of you who don't have fromInt
52 fromInt = fromInteger . toInteger