Hi,
I need to read / write epoch seconds from / to plain text files.
When I try to read POSIXTime that I use in my own data type:

data TimedClassRecT = TCR {timeStamp :: POSIXTime, classCosMap :: Map.Map String Float}
                      deriving (Eq, Read, Show)

I get the following error:

No instance for (Read POSIXTime)
      arising from the 'deriving' clause of a data type declaration
    Possible fix:
      add an instance declaration for (Read POSIXTime)
      or use a standalone 'deriving instance' declaration,
           so you can specify the instance context yourself
    When deriving the instance for (Read TimedClassRecT)

What should I do to provide Read instance for POSIXTime? I would rather not implement it myself.

Thanks!