Availability:built-in
sleep(+Time)Suspend execution Time seconds. Time is either a
floating point number or an integer. Granularity is dependent on the
system's timer granularity. A negative time causes the timer to return
immediately. A zero time yields the CPU if this is supported on the
target OS. On most non-realtime operating systems we can only ensure
execution is suspended for at least Time seconds.
On Unix systems the sleep/1
predicate is realised ---in order of preference--- by nanosleep(), usleep(), select()
if the time is below 1 minute, or sleep(). On Windows systems Sleep()
is used.