<?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>IO.hs</title> <link type='text/css' rel='stylesheet' href='hscolour.css' /> </head> <body> <pre><a name="line-1"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span> <a name="line-2"></a> <span class='hs-conid'>Handle</span><span class='hs-layout'>,</span> <span class='hs-conid'>HandlePosn</span><span class='hs-layout'>,</span> <a name="line-3"></a> <span class='hs-conid'>IOMode</span><span class='hs-layout'>(</span><span class='hs-conid'>ReadMode</span><span class='hs-layout'>,</span><span class='hs-conid'>WriteMode</span><span class='hs-layout'>,</span><span class='hs-conid'>AppendMode</span><span class='hs-layout'>,</span><span class='hs-conid'>ReadWriteMode</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <a name="line-4"></a> <span class='hs-conid'>BufferMode</span><span class='hs-layout'>(</span><span class='hs-conid'>NoBuffering</span><span class='hs-layout'>,</span><span class='hs-conid'>LineBuffering</span><span class='hs-layout'>,</span><span class='hs-conid'>BlockBuffering</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <a name="line-5"></a> <span class='hs-conid'>SeekMode</span><span class='hs-layout'>(</span><span class='hs-conid'>AbsoluteSeek</span><span class='hs-layout'>,</span><span class='hs-conid'>RelativeSeek</span><span class='hs-layout'>,</span><span class='hs-conid'>SeekFromEnd</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <a name="line-6"></a> <span class='hs-varid'>stdin</span><span class='hs-layout'>,</span> <span class='hs-varid'>stdout</span><span class='hs-layout'>,</span> <span class='hs-varid'>stderr</span><span class='hs-layout'>,</span> <a name="line-7"></a> <span class='hs-varid'>openFile</span><span class='hs-layout'>,</span> <span class='hs-varid'>hClose</span><span class='hs-layout'>,</span> <span class='hs-varid'>hFileSize</span><span class='hs-layout'>,</span> <span class='hs-varid'>hIsEOF</span><span class='hs-layout'>,</span> <span class='hs-varid'>isEOF</span><span class='hs-layout'>,</span> <a name="line-8"></a> <span class='hs-varid'>hSetBuffering</span><span class='hs-layout'>,</span> <span class='hs-varid'>hGetBuffering</span><span class='hs-layout'>,</span> <span class='hs-varid'>hFlush</span><span class='hs-layout'>,</span> <a name="line-9"></a> <span class='hs-varid'>hGetPosn</span><span class='hs-layout'>,</span> <span class='hs-varid'>hSetPosn</span><span class='hs-layout'>,</span> <span class='hs-varid'>hSeek</span><span class='hs-layout'>,</span> <a name="line-10"></a> <span class='hs-varid'>hWaitForInput</span><span class='hs-layout'>,</span> <span class='hs-varid'>hReady</span><span class='hs-layout'>,</span> <span class='hs-varid'>hGetChar</span><span class='hs-layout'>,</span> <span class='hs-varid'>hGetLine</span><span class='hs-layout'>,</span> <span class='hs-varid'>hLookAhead</span><span class='hs-layout'>,</span> <span class='hs-varid'>hGetContents</span><span class='hs-layout'>,</span> <a name="line-11"></a> <span class='hs-varid'>hPutChar</span><span class='hs-layout'>,</span> <span class='hs-varid'>hPutStr</span><span class='hs-layout'>,</span> <span class='hs-varid'>hPutStrLn</span><span class='hs-layout'>,</span> <span class='hs-varid'>hPrint</span><span class='hs-layout'>,</span> <a name="line-12"></a> <span class='hs-varid'>hIsOpen</span><span class='hs-layout'>,</span> <span class='hs-varid'>hIsClosed</span><span class='hs-layout'>,</span> <span class='hs-varid'>hIsReadable</span><span class='hs-layout'>,</span> <span class='hs-varid'>hIsWritable</span><span class='hs-layout'>,</span> <span class='hs-varid'>hIsSeekable</span><span class='hs-layout'>,</span> <a name="line-13"></a> <span class='hs-varid'>isAlreadyExistsError</span><span class='hs-layout'>,</span> <span class='hs-varid'>isDoesNotExistError</span><span class='hs-layout'>,</span> <span class='hs-varid'>isAlreadyInUseError</span><span class='hs-layout'>,</span> <a name="line-14"></a> <span class='hs-varid'>isFullError</span><span class='hs-layout'>,</span> <span class='hs-varid'>isEOFError</span><span class='hs-layout'>,</span> <a name="line-15"></a> <span class='hs-varid'>isIllegalOperation</span><span class='hs-layout'>,</span> <span class='hs-varid'>isPermissionError</span><span class='hs-layout'>,</span> <span class='hs-varid'>isUserError</span><span class='hs-layout'>,</span> <a name="line-16"></a> <span class='hs-varid'>ioeGetErrorString</span><span class='hs-layout'>,</span> <span class='hs-varid'>ioeGetHandle</span><span class='hs-layout'>,</span> <span class='hs-varid'>ioeGetFileName</span><span class='hs-layout'>,</span> <a name="line-17"></a> <span class='hs-varid'>try</span><span class='hs-layout'>,</span> <span class='hs-varid'>bracket</span><span class='hs-layout'>,</span> <span class='hs-varid'>bracket_</span><span class='hs-layout'>,</span> <a name="line-18"></a> <a name="line-19"></a> <span class='hs-comment'>-- ...and what the Prelude exports</span> <a name="line-20"></a> <span class='hs-conid'>IO</span><span class='hs-layout'>,</span> <span class='hs-conid'>FilePath</span><span class='hs-layout'>,</span> <span class='hs-conid'>IOError</span><span class='hs-layout'>,</span> <span class='hs-varid'>ioError</span><span class='hs-layout'>,</span> <span class='hs-varid'>userError</span><span class='hs-layout'>,</span> <span class='hs-varid'>catch</span><span class='hs-layout'>,</span> <span class='hs-varid'>interact</span><span class='hs-layout'>,</span> <a name="line-21"></a> <span class='hs-varid'>putChar</span><span class='hs-layout'>,</span> <span class='hs-varid'>putStr</span><span class='hs-layout'>,</span> <span class='hs-varid'>putStrLn</span><span class='hs-layout'>,</span> <span class='hs-varid'>print</span><span class='hs-layout'>,</span> <span class='hs-varid'>getChar</span><span class='hs-layout'>,</span> <span class='hs-varid'>getLine</span><span class='hs-layout'>,</span> <span class='hs-varid'>getContents</span><span class='hs-layout'>,</span> <a name="line-22"></a> <span class='hs-varid'>readFile</span><span class='hs-layout'>,</span> <span class='hs-varid'>writeFile</span><span class='hs-layout'>,</span> <span class='hs-varid'>appendFile</span><span class='hs-layout'>,</span> <span class='hs-varid'>readIO</span><span class='hs-layout'>,</span> <span class='hs-varid'>readLn</span> <a name="line-23"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span> <a name="line-24"></a> <a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span> <a name="line-26"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Error</span> <a name="line-27"></a> <a name="line-28"></a><span class='hs-comment'>-- | The 'bracket' function captures a common allocate, compute, deallocate</span> <a name="line-29"></a><span class='hs-comment'>-- idiom in which the deallocation step must occur even in the case of an</span> <a name="line-30"></a><span class='hs-comment'>-- error during computation. This is similar to try-catch-finally in Java.</span> <a name="line-31"></a><span class='hs-comment'>--</span> <a name="line-32"></a><span class='hs-comment'>-- This version handles only IO errors, as defined by Haskell 98.</span> <a name="line-33"></a><span class='hs-comment'>-- The version of @bracket@ in "Control.Exception" handles all exceptions,</span> <a name="line-34"></a><span class='hs-comment'>-- and should be used instead.</span> <a name="line-35"></a> <a name="line-36"></a><a name="bracket"></a><span class='hs-definition'>bracket</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>c</span> <a name="line-37"></a><span class='hs-definition'>bracket</span> <span class='hs-varid'>before</span> <span class='hs-varid'>after</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <a name="line-38"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>before</span> <a name="line-39"></a> <span class='hs-varid'>rs</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>try</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <a name="line-40"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>after</span> <span class='hs-varid'>x</span> <a name="line-41"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>rs</span> <span class='hs-keyword'>of</span> <a name="line-42"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span> <a name="line-43"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>ioError</span> <span class='hs-varid'>e</span> <a name="line-44"></a> <a name="line-45"></a><span class='hs-comment'>-- | A variant of 'bracket' where the middle computation doesn't want @x@.</span> <a name="line-46"></a><span class='hs-comment'>--</span> <a name="line-47"></a><span class='hs-comment'>-- This version handles only IO errors, as defined by Haskell 98.</span> <a name="line-48"></a><span class='hs-comment'>-- The version of @bracket_@ in "Control.Exception" handles all exceptions,</span> <a name="line-49"></a><span class='hs-comment'>-- and should be used instead.</span> <a name="line-50"></a> <a name="line-51"></a><a name="bracket_"></a><span class='hs-definition'>bracket_</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>c</span> <a name="line-52"></a><span class='hs-definition'>bracket_</span> <span class='hs-varid'>before</span> <span class='hs-varid'>after</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span> <a name="line-53"></a> <span class='hs-varid'>x</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>before</span> <a name="line-54"></a> <span class='hs-varid'>rs</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>try</span> <span class='hs-varid'>m</span> <a name="line-55"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>after</span> <span class='hs-varid'>x</span> <a name="line-56"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>rs</span> <span class='hs-keyword'>of</span> <a name="line-57"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span> <a name="line-58"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>ioError</span> <span class='hs-varid'>e</span> </pre></body> </html>
