| data ExitCode | 
| = | ExitSuccess | indicates successful termination; | 
| | | ExitFailure Int | indicates program failure with an exit code. The exact interpretation of the code is operating-system dependent. In particular, some values may be prohibited (e.g. 0 on a POSIX-compliant system). | 
Defines the exit codes that a program can return.
| instance Eq ExitCode | 
| instance Ord ExitCode | 
| instance Read ExitCode | 
| instance Show ExitCode | 
| exitWith :: ExitCode -> IO a | 
| exitFailure :: IO a | 
| exitSuccess :: IO a |