<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> <!-- Generated by HsColour, http://www.cs.york.ac.uk/fp/darcs/hscolour/ --> <title>System/Exit.hs</title> <link type='text/css' rel='stylesheet' href='hscolour.css' /> </head> <body> <pre><a name="line-1"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span> <a name="line-2"></a><span class='hs-comment'>-- |</span> <a name="line-3"></a><span class='hs-comment'>-- Module : System.Exit</span> <a name="line-4"></a><span class='hs-comment'>-- Copyright : (c) The University of Glasgow 2001</span> <a name="line-5"></a><span class='hs-comment'>-- License : BSD-style (see the file libraries/base/LICENSE)</span> <a name="line-6"></a><span class='hs-comment'>-- </span> <a name="line-7"></a><span class='hs-comment'>-- Maintainer : libraries@haskell.org</span> <a name="line-8"></a><span class='hs-comment'>-- Stability : provisional</span> <a name="line-9"></a><span class='hs-comment'>-- Portability : portable</span> <a name="line-10"></a><span class='hs-comment'>--</span> <a name="line-11"></a><span class='hs-comment'>-- Exiting the program.</span> <a name="line-12"></a><span class='hs-comment'>--</span> <a name="line-13"></a><span class='hs-comment'>-----------------------------------------------------------------------------</span> <a name="line-14"></a> <a name="line-15"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Exit</span> <a name="line-16"></a> <span class='hs-layout'>(</span> <a name="line-17"></a> <span class='hs-conid'>ExitCode</span><span class='hs-layout'>(</span><span class='hs-conid'>ExitSuccess</span><span class='hs-layout'>,</span><span class='hs-conid'>ExitFailure</span><span class='hs-layout'>)</span> <a name="line-18"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>exitWith</span> <span class='hs-comment'>-- :: ExitCode -> IO a</span> <a name="line-19"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>exitFailure</span> <span class='hs-comment'>-- :: IO a</span> <a name="line-20"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>exitSuccess</span> <span class='hs-comment'>-- :: IO a</span> <a name="line-21"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span> <a name="line-22"></a> <a name="line-23"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <a name="line-24"></a> <a name="line-25"></a><span class='hs-cpp'>#ifdef __GLASGOW_HASKELL__</span> <a name="line-26"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>GHC</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span> <a name="line-27"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>GHC</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <a name="line-28"></a><span class='hs-cpp'>#endif</span> <a name="line-29"></a> <a name="line-30"></a><span class='hs-cpp'>#ifdef __HUGS__</span> <a name="line-31"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Hugs</span><span class='hs-varop'>.</span><span class='hs-conid'>Prelude</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExitCode</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <a name="line-32"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span><span class='hs-varop'>.</span><span class='hs-conid'>Base</span> <a name="line-33"></a><span class='hs-cpp'>#endif</span> <a name="line-34"></a> <a name="line-35"></a><span class='hs-cpp'>#ifdef __NHC__</span> <a name="line-36"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span> <a name="line-37"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>ExitCode</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span> <a name="line-38"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>exitWith</span> <a name="line-39"></a> <span class='hs-layout'>)</span> <a name="line-40"></a><span class='hs-cpp'>#endif</span> <a name="line-41"></a> <a name="line-42"></a><span class='hs-comment'>-- ---------------------------------------------------------------------------</span> <a name="line-43"></a><span class='hs-comment'>-- exitWith</span> <a name="line-44"></a> <a name="line-45"></a><span class='hs-comment'>-- | Computation 'exitWith' @code@ throws 'ExitCode' @code@.</span> <a name="line-46"></a><span class='hs-comment'>-- Normally this terminates the program, returning @code@ to the</span> <a name="line-47"></a><span class='hs-comment'>-- program's caller.</span> <a name="line-48"></a><span class='hs-comment'>--</span> <a name="line-49"></a><span class='hs-comment'>-- On program termination, the standard 'Handle's 'stdout' and</span> <a name="line-50"></a><span class='hs-comment'>-- 'stderr' are flushed automatically; any other buffered 'Handle's</span> <a name="line-51"></a><span class='hs-comment'>-- need to be flushed manually, otherwise the buffered data will be</span> <a name="line-52"></a><span class='hs-comment'>-- discarded.</span> <a name="line-53"></a><span class='hs-comment'>--</span> <a name="line-54"></a><span class='hs-comment'>-- A program that fails in any other way is treated as if it had</span> <a name="line-55"></a><span class='hs-comment'>-- called 'exitFailure'.</span> <a name="line-56"></a><span class='hs-comment'>-- A program that terminates successfully without calling 'exitWith'</span> <a name="line-57"></a><span class='hs-comment'>-- explicitly is treated as it it had called 'exitWith' 'ExitSuccess'.</span> <a name="line-58"></a><span class='hs-comment'>--</span> <a name="line-59"></a><span class='hs-comment'>-- As an 'ExitCode' is not an 'IOError', 'exitWith' bypasses</span> <a name="line-60"></a><span class='hs-comment'>-- the error handling in the 'IO' monad and cannot be intercepted by</span> <a name="line-61"></a><span class='hs-comment'>-- 'catch' from the "Prelude". However it is a 'SomeException', and can</span> <a name="line-62"></a><span class='hs-comment'>-- be caught using the functions of "Control.Exception". This means</span> <a name="line-63"></a><span class='hs-comment'>-- that cleanup computations added with 'Control.Exception.bracket'</span> <a name="line-64"></a><span class='hs-comment'>-- (from "Control.Exception") are also executed properly on 'exitWith'.</span> <a name="line-65"></a><span class='hs-comment'>--</span> <a name="line-66"></a><span class='hs-comment'>-- Note: in GHC, 'exitWith' should be called from the main program</span> <a name="line-67"></a><span class='hs-comment'>-- thread in order to exit the process. When called from another</span> <a name="line-68"></a><span class='hs-comment'>-- thread, 'exitWith' will throw an 'ExitException' as normal, but the</span> <a name="line-69"></a><span class='hs-comment'>-- exception will not cause the process itself to exit.</span> <a name="line-70"></a><span class='hs-comment'>--</span> <a name="line-71"></a><span class='hs-cpp'>#ifndef __NHC__</span> <a name="line-72"></a><a name="exitWith"></a><span class='hs-definition'>exitWith</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ExitCode</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <a name="line-73"></a><span class='hs-definition'>exitWith</span> <span class='hs-conid'>ExitSuccess</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>throwIO</span> <span class='hs-conid'>ExitSuccess</span> <a name="line-74"></a><span class='hs-definition'>exitWith</span> <span class='hs-varid'>code</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>ExitFailure</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span> <a name="line-75"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>n</span> <span class='hs-varop'>/=</span> <span class='hs-num'>0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>throwIO</span> <span class='hs-varid'>code</span> <a name="line-76"></a><span class='hs-cpp'>#ifdef __GLASGOW_HASKELL__</span> <a name="line-77"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>ioError</span> <span class='hs-layout'>(</span><span class='hs-conid'>IOError</span> <span class='hs-conid'>Nothing</span> <span class='hs-conid'>InvalidArgument</span> <span class='hs-str'>"exitWith"</span> <span class='hs-str'>"ExitFailure 0"</span> <span class='hs-conid'>Nothing</span> <span class='hs-conid'>Nothing</span><span class='hs-layout'>)</span> <a name="line-78"></a><span class='hs-cpp'>#endif</span> <a name="line-79"></a><span class='hs-cpp'>#endif /* ! __NHC__ */</span> <a name="line-80"></a> <a name="line-81"></a><a name="exitFailure"></a><span class='hs-comment'>-- | The computation 'exitFailure' is equivalent to</span> <a name="line-82"></a><span class='hs-comment'>-- 'exitWith' @(@'ExitFailure' /exitfail/@)@,</span> <a name="line-83"></a><span class='hs-comment'>-- where /exitfail/ is implementation-dependent.</span> <a name="line-84"></a><span class='hs-definition'>exitFailure</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <a name="line-85"></a><span class='hs-definition'>exitFailure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>exitWith</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExitFailure</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <a name="line-86"></a> <a name="line-87"></a><a name="exitSuccess"></a><span class='hs-comment'>-- | The computation 'exitSuccess' is equivalent to</span> <a name="line-88"></a><span class='hs-comment'>-- 'exitWith' 'ExitSuccess', It terminates the program</span> <a name="line-89"></a><span class='hs-comment'>-- successfully.</span> <a name="line-90"></a><span class='hs-definition'>exitSuccess</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <a name="line-91"></a><span class='hs-definition'>exitSuccess</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>exitWith</span> <span class='hs-conid'>ExitSuccess</span> </pre></body> </html>
