Cookbook/Dates And Time
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Revision as of 14:33, 12 January 2014 by Artyom Kazak (talk | contribs)
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Finding today's date
import Data.Time
c <- getCurrentTime --> 2009-04-21 14:25:29.5585588 UTC
(y,m,d) = toGregorian $ utctDay c --> (2009,4,21)
Adding to or subtracting from a date
| Problem | Solution | Examples |
|---|---|---|
| adding days to a date | addDays | import Data.Time
a = fromGregorian 2009 12 31 --> 2009-12-31
b = addDays 1 a --> 2010-01-01
|
| subtracting days from a date | addDays | import Data.Time
a = fromGregorian 2009 12 31 --> 2009-12-31
b = addDays (-7) a --> 2009-12-24
|
Difference of two dates
| Problem | Solution | Examples |
|---|---|---|
| calculating the difference of two dates | diffDays | import Data.Time
a = fromGregorian 2009 12 31 --> 2009-12-31
b = fromGregorian 2010 12 31 --> 2010-12-31
diffDays b a --> 365
|
CPU time
Use System.CPUTime.getCPUTime to get the CPU time in picoseconds.
You can time a computation like this
getCPUTimeDouble :: IO Double
getCPUTimeDouble = do t <- System.CPUTime.getCPUTime; return ((fromInteger t) * 1e-12)
main = do
t1 <- getCPUTimeDouble
print (fib 30)
t2 <- getCPUTimeDouble
print (t2-t1)