System.PosixCompat.Unistd

This module makes the operations exported by System.Posix.Unistd available on all platforms. On POSIX systems it re-exports operations from System.Posix.Unistd, on other platforms it emulates the operations as far as possible.

System environment

data SystemID

Constructors

SystemID

Fields

• systemName :: String
• nodeName :: String
• release :: String
• version :: String
• machine :: String

getSystemID :: IO SystemID

Sleeping

sleep :: Int -> IO Int

Sleep for the specified duration (in seconds). Returns the time remaining (if the sleep was interrupted by a signal, for example).

GHC Note: threadDelay is a better choice. Since GHC uses signals for its internal clock, a call to sleep will usually be interrupted immediately. That makes sleep unusable in a program compiled with GHC, unless the RTS timer is disabled (with +RTS -V0). Furthermore, without the -threaded option, sleep will block all other user threads. Even with the -threaded option, sleep requires a full OS thread to itself. threadDelay has none of these shortcomings.

usleep :: Int -> IO ()

Sleep for the specified duration (in microseconds).

GHC Note: threadDelay is a better choice. Without the -threaded option, usleep will block all other user threads. Even with the -threaded option, usleep requires a full OS thread to itself. threadDelay has neither of these shortcomings.

nanosleep :: Integer -> IO ()

Sleep for the specified duration (in nanoseconds)

GHC Note: the comment for usleep also applies here.