haskell，如何将POSIXTime类型转换为字符串

Question

Prelude> import Data.Time.Clock.POSIX (getPOSIXTime) 
Prelude Data.Time.Clock.POSIX> ptime <- getPOSIXTime 
Prelude Data.Time.Clock.POSIX> ptime 
1360059876.245525s 
Prelude Data.Time.Clock.POSIX> :t ptime 
ptime :: Data.Time.Clock.POSIX.POSIXTime 
Prelude Data.Time.Clock.POSIX> 

我想将ptime转换为字符串类型，它怎么做？

Answer 1

使用posixSecondsToUTCTime（也在Data.Time.Clock.POSIX中）将POSIXTime转换为UTCTime;然后从Data.Time.Format的formatTime将UTCTime格式化为String。

例如

formatTime defaultTimeLocale "%FT%T" (posixSecondsToUTCTime ptime) 
--^ISO 8601 
formatTime defaultTimeLocale "%s%Qs" (posixSecondsToUTCTime ptime) 
--^fractional seconds since the epoch (but see caveat noted in documentation) 

（defaultTimeLocale是System.Locale。）