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GHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27

Modulebase-compat-0.14.1Haskell2010

System.Exit.Compat

  • 1 type
  • 5 values
datadata ExitCode
#

Defines the exit codes that a program can return.

Constructors

  • 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).

Instances8Eq, Ord, Read, Show, Generic, Exception, …
valueexitWith :: ExitCode -> IO a
#

Computation exitWith code throws ExitCode code. Normally this terminates the program, returning code to the program's caller.

On program termination, the standard Handles stdout and stderr are flushed automatically; any other buffered Handles need to be flushed manually, otherwise the buffered data will be discarded.

A program that fails in any other way is treated as if it had called exitFailure. A program that terminates successfully without calling exitWith explicitly is treated as if it had called exitWith ExitSuccess.

As an ExitCode is an Exception, it can be caught using the functions of Control.Exception. This means that cleanup computations added with bracket (from Control.Exception) are also executed properly on exitWith.

Note: in GHC, exitWith should be called from the main program thread in order to exit the process. When called from another thread, exitWith will throw an ExitCode as normal, but the exception will not cause the process itself to exit.