Get the current POSIX time from the system clock.
Get the POSIX time. If SOURCE_DATE_EPOCH is set to a unix time, it is used instead of the current time.
Return the current system POSIX time via gettimeofday, or getSystemTimeAsFileTime on Windows. See also getCurrentTime, getZonedTime.
realToFrac of Clock.Posix.getPOSIXTime
get_ct = getCurrentTimeAsPosix
get_pt = getPosixTimeAsPosix
(ct,pt) <- get_ct >>= \t0 -> get_pt >>= \t1 -> return (t0,t1)
print (pt - ct,pt - ct < 1e-5)