<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Exception</title><link href="ocean.css" rel="stylesheet" type="text/css" title="Ocean" /><script src="haddock-util.js" type="text/javascript"></script><script type="text/javascript">//<![CDATA[ window.onload = function () {pageLoad();setSynopsis("mini_Exception.html");}; //]]> </script></head><body><div id="package-header"><ul class="links" id="page-menu"><li><a href="index.html">Contents</a></li><li><a href="doc-index.html">Index</a></li></ul><p class="caption">ghc-7.4.2: The GHC API</p></div><div id="content"><div id="module-header"><table class="info"><tr><th>Safe Haskell</th><td>Safe-Infered</td></tr></table><p class="caption">Exception</p></div><div id="synopsis"><p id="control.syn" class="caption expander" onclick="toggleSection('syn')">Synopsis</p><ul id="section.syn" class="hide" onclick="toggleSection('syn')"><li class="src short">module <a href="../base-4.5.1.0/Control-Exception.html">Control.Exception</a></li><li class="src short"><a href="#v:catchIO">catchIO</a> :: <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a -> (<a href="../base-4.5.1.0/Control-Exception-Base.html#t:IOException">IOException</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a) -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a</li><li class="src short"><a href="#v:handleIO">handleIO</a> :: (<a href="../base-4.5.1.0/Control-Exception-Base.html#t:IOException">IOException</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a) -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a</li><li class="src short"><a href="#v:tryIO">tryIO</a> :: <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/Data-Either.html#t:Either">Either</a> <a href="../base-4.5.1.0/Control-Exception-Base.html#t:IOException">IOException</a> a)</li><li class="src short"><span class="keyword">class</span> <a href="../base-4.5.1.0/Control-Monad.html#t:Monad">Monad</a> m => <a href="#t:ExceptionMonad">ExceptionMonad</a> m <span class="keyword">where</span><ul class="subs"><li><a href="#v:gcatch">gcatch</a> :: <a href="Panic.html#t:Exception">Exception</a> e => m a -> (e -> m a) -> m a</li><li><a href="#v:gmask">gmask</a> :: ((m a -> m a) -> m b) -> m b</li><li><a href="#v:gbracket">gbracket</a> :: m a -> (a -> m b) -> (a -> m c) -> m c</li><li><a href="#v:gfinally">gfinally</a> :: m a -> m b -> m a</li><li><a href="#v:gblock">gblock</a> :: m a -> m a</li><li><a href="#v:gunblock">gunblock</a> :: m a -> m a</li></ul></li><li class="src short"><a href="#v:gtry">gtry</a> :: (<a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> m, <a href="Panic.html#t:Exception">Exception</a> e) => m a -> m (<a href="../base-4.5.1.0/Data-Either.html#t:Either">Either</a> e a)</li><li class="src short"><a href="#v:ghandle">ghandle</a> :: (<a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> m, <a href="Panic.html#t:Exception">Exception</a> e) => (e -> m a) -> m a -> m a</li><li class="src short"><a href="#v:gonException">gonException</a> :: <a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> m => m a -> m b -> m a</li></ul></div><div id="interface"><h1>Documentation</h1><div class="top"><p class="src">module <a href="../base-4.5.1.0/Control-Exception.html">Control.Exception</a></p></div><div class="top"><p class="src"><a name="v:catchIO" class="def">catchIO</a> :: <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a -> (<a href="../base-4.5.1.0/Control-Exception-Base.html#t:IOException">IOException</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a) -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a</p></div><div class="top"><p class="src"><a name="v:handleIO" class="def">handleIO</a> :: (<a href="../base-4.5.1.0/Control-Exception-Base.html#t:IOException">IOException</a> -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a) -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a</p></div><div class="top"><p class="src"><a name="v:tryIO" class="def">tryIO</a> :: <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> a -> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a> (<a href="../base-4.5.1.0/Data-Either.html#t:Either">Either</a> <a href="../base-4.5.1.0/Control-Exception-Base.html#t:IOException">IOException</a> a)</p></div><div class="top"><p class="src"><span class="keyword">class</span> <a href="../base-4.5.1.0/Control-Monad.html#t:Monad">Monad</a> m => <a name="t:ExceptionMonad" class="def">ExceptionMonad</a> m <span class="keyword">where</span></p><div class="doc"><p>A monad that can catch exceptions. A minimal definition requires a definition of <code><a href="Exception.html#v:gcatch">gcatch</a></code>. </p><p>Implementations on top of <code><a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a></code> should implement <code><a href="Exception.html#v:gblock">gblock</a></code> and <code><a href="Exception.html#v:gunblock">gunblock</a></code> to eventually call the primitives <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:block">block</a></code> and <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:unblock">unblock</a></code> respectively. These are used for implementations that support asynchronous exceptions. The default implementations of <code><a href="Exception.html#v:gbracket">gbracket</a></code> and <code><a href="Exception.html#v:gfinally">gfinally</a></code> use <code><a href="Exception.html#v:gblock">gblock</a></code> and <code><a href="Exception.html#v:gunblock">gunblock</a></code> thus rarely require overriding. </p></div><div class="subs methods"><p class="caption">Methods</p><p class="src"><a name="v:gcatch" class="def">gcatch</a> :: <a href="Panic.html#t:Exception">Exception</a> e => m a -> (e -> m a) -> m a</p><div class="doc"><p>Generalised version of <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:catch">catch</a></code>, allowing an arbitrary exception handling monad instead of just <code><a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a></code>. </p></div><p class="src"><a name="v:gmask" class="def">gmask</a> :: ((m a -> m a) -> m b) -> m b</p><div class="doc"><p>Generalised version of <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:mask_">mask_</a></code>, allowing an arbitrary exception handling monad instead of just <code><a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a></code>. </p></div><p class="src"><a name="v:gbracket" class="def">gbracket</a> :: m a -> (a -> m b) -> (a -> m c) -> m c</p><div class="doc"><p>Generalised version of <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:bracket">bracket</a></code>, allowing an arbitrary exception handling monad instead of just <code><a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a></code>. </p></div><p class="src"><a name="v:gfinally" class="def">gfinally</a> :: m a -> m b -> m a</p><div class="doc"><p>Generalised version of <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:finally">finally</a></code>, allowing an arbitrary exception handling monad instead of just <code><a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a></code>. </p></div><p class="src"><a name="v:gblock" class="def">gblock</a> :: m a -> m a</p><div class="doc"><p>DEPRECATED, here for backwards compatibilty. Instances can define either <code><a href="Exception.html#v:gmask">gmask</a></code>, or both <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:block">block</a></code> and <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:unblock">unblock</a></code>. </p></div><p class="src"><a name="v:gunblock" class="def">gunblock</a> :: m a -> m a</p><div class="doc"><p>DEPRECATED, here for backwards compatibilty Instances can define either <code><a href="Exception.html#v:gmask">gmask</a></code>, or both <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:block">block</a></code> and <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:unblock">unblock</a></code>. </p></div></div><div class="subs instances"><p id="control.i:ExceptionMonad" class="caption collapser" onclick="toggleSection('i:ExceptionMonad')">Instances</p><div id="section.i:ExceptionMonad" class="show"><table><tr><td class="src"><a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> <a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> <a href="GhcMonad.html#t:Ghc">Ghc</a></td><td class="doc empty"> </td></tr><tr><td class="src"><a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> m => <a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> (<a href="GhcMonad.html#t:GhcT">GhcT</a> m)</td><td class="doc empty"> </td></tr></table></div></div></div><div class="top"><p class="src"><a name="v:gtry" class="def">gtry</a> :: (<a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> m, <a href="Panic.html#t:Exception">Exception</a> e) => m a -> m (<a href="../base-4.5.1.0/Data-Either.html#t:Either">Either</a> e a)</p></div><div class="top"><p class="src"><a name="v:ghandle" class="def">ghandle</a> :: (<a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> m, <a href="Panic.html#t:Exception">Exception</a> e) => (e -> m a) -> m a -> m a</p><div class="doc"><p>Generalised version of <code><a href="../base-4.5.1.0/Control-Exception-Base.html#v:handle">handle</a></code>, allowing an arbitrary exception handling monad instead of just <code><a href="../base-4.5.1.0/System-IO.html#t:IO">IO</a></code>. </p></div></div><div class="top"><p class="src"><a name="v:gonException" class="def">gonException</a> :: <a href="Exception.html#t:ExceptionMonad">ExceptionMonad</a> m => m a -> m b -> m a</p><div class="doc"><p>Always executes the first argument. If this throws an exception the second argument is executed and the exception is raised again. </p></div></div></div></div><div id="footer"><p>Produced by <a href="http://www.haskell.org/haddock/">Haddock</a> version 2.11.0</p></div></body></html>