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<title>src/Control/Monad/CatchIO.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE ExistentialQuantification, ScopedTypeVariables #-}</span>
<a name="line-2"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>CatchIO</span>
<a name="line-3"></a> <span class='hs-layout'>(</span>
<a name="line-4"></a> <span class='hs-conid'>MonadCatchIO</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-5"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-6"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>throw</span>
<a name="line-7"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>try</span><span class='hs-layout'>,</span> <span class='hs-varid'>tryJust</span>
<a name="line-8"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Handler</span><span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-varid'>catches</span>
<a name="line-9"></a> <span class='hs-comment'>-- * Utilities</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>bracket</span>
<a name="line-11"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>bracket_</span>
<a name="line-12"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>bracketOnError</span>
<a name="line-13"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>finally</span>
<a name="line-14"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>onException</span>
<a name="line-15"></a> <span class='hs-layout'>)</span>
<a name="line-16"></a>
<a name="line-17"></a><span class='hs-keyword'>where</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <span class='hs-varid'>hiding</span> <span class='hs-layout'>(</span> <span class='hs-varid'>catch</span> <span class='hs-layout'>)</span>
<a name="line-20"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varop'><$></span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-21"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</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'>Extensible</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>E</span>
<a name="line-22"></a>
<a name="line-23"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Class</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadIO</span><span class='hs-layout'>,</span><span class='hs-varid'>liftIO</span><span class='hs-layout'>)</span>
<a name="line-24"></a>
<a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Cont</span> <span class='hs-layout'>(</span><span class='hs-conid'>ContT</span><span class='hs-layout'>(</span><span class='hs-conid'>ContT</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span><span class='hs-varid'>runContT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapContT</span> <span class='hs-layout'>)</span>
<a name="line-26"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Error</span> <span class='hs-layout'>(</span><span class='hs-conid'>ErrorT</span> <span class='hs-layout'>,</span><span class='hs-varid'>runErrorT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapErrorT</span> <span class='hs-layout'>,</span><span class='hs-conid'>Error</span><span class='hs-layout'>)</span>
<a name="line-27"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Identity</span> <span class='hs-layout'>(</span><span class='hs-conid'>IdentityT</span> <span class='hs-layout'>,</span><span class='hs-varid'>runIdentityT</span><span class='hs-layout'>,</span><span class='hs-varid'>mapIdentityT</span><span class='hs-layout'>)</span>
<a name="line-28"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>List</span> <span class='hs-layout'>(</span><span class='hs-conid'>ListT</span><span class='hs-layout'>(</span><span class='hs-conid'>ListT</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span><span class='hs-varid'>runListT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapListT</span> <span class='hs-layout'>)</span>
<a name="line-29"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Maybe</span> <span class='hs-layout'>(</span><span class='hs-conid'>MaybeT</span> <span class='hs-layout'>,</span><span class='hs-varid'>runMaybeT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapMaybeT</span> <span class='hs-layout'>)</span>
<a name="line-30"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>RWS</span> <span class='hs-layout'>(</span><span class='hs-conid'>RWST</span><span class='hs-layout'>(</span><span class='hs-conid'>RWST</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span><span class='hs-varid'>runRWST</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapRWST</span> <span class='hs-layout'>)</span>
<a name="line-31"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>RWS</span><span class='hs-varop'>.</span><span class='hs-conid'>Strict</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Strict</span> <span class='hs-layout'>(</span><span class='hs-conid'>RWST</span><span class='hs-layout'>(</span><span class='hs-conid'>RWST</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span><span class='hs-varid'>runRWST</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapRWST</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'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Reader</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReaderT</span><span class='hs-layout'>(</span><span class='hs-conid'>ReaderT</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span><span class='hs-varid'>runReaderT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapReaderT</span> <span class='hs-layout'>)</span>
<a name="line-33"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>State</span> <span class='hs-layout'>(</span><span class='hs-conid'>StateT</span><span class='hs-layout'>(</span><span class='hs-conid'>StateT</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span><span class='hs-varid'>runStateT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapStateT</span> <span class='hs-layout'>)</span>
<a name="line-34"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>State</span><span class='hs-varop'>.</span><span class='hs-conid'>Strict</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Strict</span> <span class='hs-layout'>(</span><span class='hs-conid'>StateT</span><span class='hs-layout'>(</span><span class='hs-conid'>StateT</span><span class='hs-layout'>)</span> <span class='hs-layout'>,</span><span class='hs-varid'>runStateT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapStateT</span> <span class='hs-layout'>)</span>
<a name="line-35"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Writer</span> <span class='hs-layout'>(</span><span class='hs-conid'>WriterT</span> <span class='hs-layout'>,</span><span class='hs-varid'>runWriterT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapWriterT</span> <span class='hs-layout'>)</span>
<a name="line-36"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Writer</span><span class='hs-varop'>.</span><span class='hs-conid'>Strict</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Strict</span> <span class='hs-layout'>(</span><span class='hs-conid'>WriterT</span> <span class='hs-layout'>,</span><span class='hs-varid'>runWriterT</span> <span class='hs-layout'>,</span><span class='hs-varid'>mapWriterT</span> <span class='hs-layout'>)</span>
<a name="line-37"></a>
<a name="line-38"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Monoid</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monoid</span><span class='hs-layout'>)</span>
<a name="line-39"></a>
<a name="line-40"></a>
<a name="line-41"></a><a name="MonadCatchIO"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>MonadIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>where</span>
<a name="line-42"></a> <span class='hs-comment'>-- | Generalized version of 'E.catch'</span>
<a name="line-43"></a> <span class='hs-varid'>catch</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-44"></a>
<a name="line-45"></a> <span class='hs-comment'>-- | Generalized version of 'E.block'</span>
<a name="line-46"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-47"></a>
<a name="line-48"></a> <span class='hs-comment'>-- | Generalized version of 'E.unblock'</span>
<a name="line-49"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-50"></a>
<a name="line-51"></a>
<a name="line-52"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-conid'>IO</span> <span class='hs-keyword'>where</span>
<a name="line-53"></a> <span class='hs-varid'>catch</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>catch</span>
<a name="line-54"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>block</span>
<a name="line-55"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>unblock</span>
<a name="line-56"></a>
<a name="line-57"></a><span class='hs-comment'>-- | Warning: this instance is somewhat contentious.</span>
<a name="line-58"></a><span class='hs-comment'>-- </span>
<a name="line-59"></a><span class='hs-comment'>-- In the same way that the @ErrorT e@ instance may fail to perform the final</span>
<a name="line-60"></a><span class='hs-comment'>-- action, due to the \"early exit\" behaviour of the monad, this instance</span>
<a name="line-61"></a><span class='hs-comment'>-- may perform the final action any number of times, due to the nonlinear</span>
<a name="line-62"></a><span class='hs-comment'>-- nature of the continuation monad.</span>
<a name="line-63"></a><span class='hs-comment'>-- </span>
<a name="line-64"></a><span class='hs-comment'>-- See the mailing list message</span>
<a name="line-65"></a><span class='hs-comment'>-- <<a href="http://web.archiveorange.com/archive/v/nDNOvaYx1poDHZNlmlgh">http://web.archiveorange.com/archive/v/nDNOvaYx1poDHZNlmlgh</a>></span>
<a name="line-66"></a><span class='hs-comment'>-- for an example of what can go wrong (freeing memory twice).</span>
<a name="line-67"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>ContT</span> <span class='hs-varid'>r</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-68"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ContT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runContT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runContT</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>c</span>
<a name="line-69"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapContT</span> <span class='hs-varid'>block</span>
<a name="line-70"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapContT</span> <span class='hs-varid'>unblock</span>
<a name="line-71"></a>
<a name="line-72"></a><span class='hs-comment'>-- | Warning: this instance is somewhat contentious.</span>
<a name="line-73"></a><span class='hs-comment'>-- </span>
<a name="line-74"></a><span class='hs-comment'>-- Note that in monads that fall under this instance (the most basic example</span>
<a name="line-75"></a><span class='hs-comment'>-- is @ErrorT e IO@), there are errors of two sorts:</span>
<a name="line-76"></a><span class='hs-comment'>-- </span>
<a name="line-77"></a><span class='hs-comment'>-- 1. exceptions, (i.e., exceptional values in the underlying @IO@ monad);</span>
<a name="line-78"></a><span class='hs-comment'>-- </span>
<a name="line-79"></a><span class='hs-comment'>-- 2. error values of type @e@, introduced by the @ErrorT e@ part of the monad.</span>
<a name="line-80"></a><span class='hs-comment'>-- </span>
<a name="line-81"></a><span class='hs-comment'>-- The instance takes no special action to deal with errors of type 2.</span>
<a name="line-82"></a><span class='hs-comment'>-- In particular, 'bracket' will not perform its second argument, if</span>
<a name="line-83"></a><span class='hs-comment'>-- its third argument decides to \"exit early\" by throwing an error of type 2.</span>
<a name="line-84"></a><span class='hs-comment'>-- </span>
<a name="line-85"></a><span class='hs-comment'>-- This may or may not be what you want.</span>
<a name="line-86"></a><span class='hs-comment'>-- </span>
<a name="line-87"></a><span class='hs-comment'>-- See the mailing list thread starting with</span>
<a name="line-88"></a><span class='hs-comment'>-- <<a href="http://www.mail-archive.com/haskell-cafe@haskell.org/msg82859.html">http://www.mail-archive.com/haskell-cafe@haskell.org/msg82859.html</a>></span>
<a name="line-89"></a><span class='hs-comment'>-- for some details.</span>
<a name="line-90"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Error</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>ErrorT</span> <span class='hs-varid'>e</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-91"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapErrorT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>m'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m'</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runErrorT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span>
<a name="line-92"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapErrorT</span> <span class='hs-varid'>block</span>
<a name="line-93"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapErrorT</span> <span class='hs-varid'>unblock</span>
<a name="line-94"></a>
<a name="line-95"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>IdentityT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-96"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapIdentityT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>m'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m'</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runIdentityT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span>
<a name="line-97"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapIdentityT</span> <span class='hs-varid'>block</span>
<a name="line-98"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapIdentityT</span> <span class='hs-varid'>unblock</span>
<a name="line-99"></a>
<a name="line-100"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>ListT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-101"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ListT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>runListT</span> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runListT</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span>
<a name="line-102"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapListT</span> <span class='hs-varid'>block</span>
<a name="line-103"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapListT</span> <span class='hs-varid'>unblock</span>
<a name="line-104"></a>
<a name="line-105"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>MaybeT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-106"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapMaybeT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>m'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m'</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runMaybeT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span>
<a name="line-107"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapMaybeT</span> <span class='hs-varid'>block</span>
<a name="line-108"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapMaybeT</span> <span class='hs-varid'>unblock</span>
<a name="line-109"></a>
<a name="line-110"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monoid</span> <span class='hs-varid'>w</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>RWST</span> <span class='hs-varid'>r</span> <span class='hs-varid'>w</span> <span class='hs-varid'>s</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-111"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>RWST</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runRWST</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span> <span class='hs-varid'>s</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runRWST</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>s</span>
<a name="line-112"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapRWST</span> <span class='hs-varid'>block</span>
<a name="line-113"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapRWST</span> <span class='hs-varid'>unblock</span>
<a name="line-114"></a>
<a name="line-115"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monoid</span> <span class='hs-varid'>w</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-conid'>RWST</span> <span class='hs-varid'>r</span> <span class='hs-varid'>w</span> <span class='hs-varid'>s</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-116"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-conid'>RWST</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>runRWST</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span> <span class='hs-varid'>s</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>runRWST</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span> <span class='hs-varid'>s</span>
<a name="line-117"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>mapRWST</span> <span class='hs-varid'>block</span>
<a name="line-118"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>mapRWST</span> <span class='hs-varid'>unblock</span>
<a name="line-119"></a>
<a name="line-120"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReaderT</span> <span class='hs-varid'>r</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-121"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ReaderT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runReaderT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>r</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runReaderT</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>r</span>
<a name="line-122"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapReaderT</span> <span class='hs-varid'>block</span>
<a name="line-123"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapReaderT</span> <span class='hs-varid'>unblock</span>
<a name="line-124"></a>
<a name="line-125"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>StateT</span> <span class='hs-varid'>s</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-126"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>StateT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runStateT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>s</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runStateT</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span>
<a name="line-127"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapStateT</span> <span class='hs-varid'>block</span>
<a name="line-128"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapStateT</span> <span class='hs-varid'>unblock</span>
<a name="line-129"></a>
<a name="line-130"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-conid'>StateT</span> <span class='hs-varid'>s</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-131"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-conid'>StateT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>s</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>runStateT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>s</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>runStateT</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>s</span>
<a name="line-132"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>mapStateT</span> <span class='hs-varid'>block</span>
<a name="line-133"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>mapStateT</span> <span class='hs-varid'>unblock</span>
<a name="line-134"></a>
<a name="line-135"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monoid</span> <span class='hs-varid'>w</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>WriterT</span> <span class='hs-varid'>w</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-136"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapWriterT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>m'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m'</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runWriterT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span>
<a name="line-137"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapWriterT</span> <span class='hs-varid'>block</span>
<a name="line-138"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapWriterT</span> <span class='hs-varid'>unblock</span>
<a name="line-139"></a>
<a name="line-140"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Monoid</span> <span class='hs-varid'>w</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-conid'>WriterT</span> <span class='hs-varid'>w</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-141"></a> <span class='hs-varid'>m</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>mapWriterT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>m'</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m'</span> <span class='hs-varop'>`catch`</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>runWriterT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span>
<a name="line-142"></a> <span class='hs-varid'>block</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>mapWriterT</span> <span class='hs-varid'>block</span>
<a name="line-143"></a> <span class='hs-varid'>unblock</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Strict</span><span class='hs-varop'>.</span><span class='hs-varid'>mapWriterT</span> <span class='hs-varid'>unblock</span>
<a name="line-144"></a>
<a name="line-145"></a><a name="throw"></a><span class='hs-comment'>-- | Generalized version of 'E.throwIO'</span>
<a name="line-146"></a><span class='hs-definition'>throw</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-147"></a><span class='hs-definition'>throw</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-varop'>.</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>throwIO</span>
<a name="line-148"></a>
<a name="line-149"></a><a name="try"></a><span class='hs-comment'>-- | Generalized version of 'E.try'</span>
<a name="line-150"></a><span class='hs-definition'>try</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Either</span> <span class='hs-varid'>e</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-151"></a><span class='hs-definition'>try</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>catch</span> <span class='hs-layout'>(</span><span class='hs-conid'>Right</span> <span class='hs-varop'><$></span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-conid'>Left</span><span class='hs-layout'>)</span>
<a name="line-152"></a>
<a name="line-153"></a><a name="tryJust"></a><span class='hs-comment'>-- | Generalized version of 'E.tryJust'</span>
<a name="line-154"></a><span class='hs-definition'>tryJust</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Functor</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span>
<a name="line-155"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Maybe</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Either</span> <span class='hs-varid'>b</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-156"></a><span class='hs-definition'>tryJust</span> <span class='hs-varid'>p</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-157"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>try</span> <span class='hs-varid'>a</span>
<a name="line-158"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>r</span> <span class='hs-keyword'>of</span>
<a name="line-159"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>v</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Right</span> <span class='hs-varid'>v</span><span class='hs-layout'>)</span>
<a name="line-160"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>case</span> <span class='hs-varid'>p</span> <span class='hs-varid'>e</span> <span class='hs-keyword'>of</span>
<a name="line-161"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>throw</span> <span class='hs-varid'>e</span> <span class='hs-varop'>`asTypeOf`</span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Left</span> <span class='hs-varid'>undefined</span><span class='hs-layout'>)</span>
<a name="line-162"></a> <span class='hs-conid'>Just</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Left</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-163"></a>
<a name="line-164"></a><a name="Handler"></a><span class='hs-comment'>-- | Generalized version of 'E.Handler'</span>
<a name="line-165"></a><a name="Handler"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Handler</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>forall</span> <span class='hs-varid'>e</span> <span class='hs-varop'>.</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-conid'>Exception</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Handler</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-166"></a>
<a name="line-167"></a><a name="catches"></a><span class='hs-comment'>-- | Generalized version of 'E.catches'</span>
<a name="line-168"></a><span class='hs-definition'>catches</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyglyph'>[</span><span class='hs-conid'>Handler</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-169"></a><span class='hs-definition'>catches</span> <span class='hs-varid'>a</span> <span class='hs-varid'>handlers</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>a</span> <span class='hs-varop'>`catch`</span> <span class='hs-varid'>handler</span> <span class='hs-keyword'>where</span>
<a name="line-170"></a> <span class='hs-varid'>handler</span> <span class='hs-varid'>e</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>foldr</span> <span class='hs-varid'>tryH</span> <span class='hs-layout'>(</span><span class='hs-varid'>throw</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span> <span class='hs-varid'>handlers</span> <span class='hs-keyword'>where</span>
<a name="line-171"></a> <span class='hs-varid'>tryH</span> <span class='hs-layout'>(</span><span class='hs-conid'>Handler</span> <span class='hs-varid'>h</span><span class='hs-layout'>)</span> <span class='hs-varid'>res</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>maybe</span> <span class='hs-varid'>res</span> <span class='hs-varid'>h</span> <span class='hs-varop'>$</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>fromException</span> <span class='hs-varid'>e</span>
<a name="line-172"></a>
<a name="line-173"></a><a name="bracket"></a><span class='hs-comment'>-- | Generalized version of 'E.bracket'</span>
<a name="line-174"></a><span class='hs-definition'>bracket</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span>
<a name="line-175"></a><span class='hs-definition'>bracket</span> <span class='hs-varid'>before</span> <span class='hs-varid'>after</span> <span class='hs-varid'>thing</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>block</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-176"></a> <span class='hs-varid'>a</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>before</span>
<a name="line-177"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>unblock</span> <span class='hs-layout'>(</span><span class='hs-varid'>thing</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varop'>`onException`</span> <span class='hs-varid'>after</span> <span class='hs-varid'>a</span>
<a name="line-178"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>after</span> <span class='hs-varid'>a</span>
<a name="line-179"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-180"></a>
<a name="line-181"></a><a name="onException"></a><span class='hs-comment'>-- | Generalized version of 'E.onException'</span>
<a name="line-182"></a><span class='hs-definition'>onException</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-183"></a><span class='hs-definition'>onException</span> <span class='hs-varid'>a</span> <span class='hs-varid'>onEx</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>a</span> <span class='hs-varop'>`catch`</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span> <span class='hs-layout'>(</span><span class='hs-varid'>e</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-conid'>SomeException</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>onEx</span> <span class='hs-varop'>>></span> <span class='hs-varid'>throw</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span>
<a name="line-184"></a>
<a name="line-185"></a><a name="bracket_"></a><span class='hs-comment'>-- | A variant of 'bracket' where the return value from the first computation</span>
<a name="line-186"></a><span class='hs-comment'>-- is not required.</span>
<a name="line-187"></a><span class='hs-definition'>bracket_</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span>
<a name="line-188"></a> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ computation to run first (\"acquire resource\")</span>
<a name="line-189"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-comment'>-- ^ computation to run last (\"release resource\")</span>
<a name="line-190"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-- ^ computation to run in-between</span>
<a name="line-191"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-- returns the value from the in-between computation</span>
<a name="line-192"></a><span class='hs-definition'>bracket_</span> <span class='hs-varid'>before</span> <span class='hs-varid'>after</span> <span class='hs-varid'>thing</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>block</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-193"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>before</span>
<a name="line-194"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>unblock</span> <span class='hs-varid'>thing</span> <span class='hs-varop'>`onException`</span> <span class='hs-varid'>after</span>
<a name="line-195"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>after</span>
<a name="line-196"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-197"></a>
<a name="line-198"></a><a name="finally"></a><span class='hs-comment'>-- | A specialised variant of 'bracket' with just a computation to run</span>
<a name="line-199"></a><span class='hs-comment'>-- afterward.</span>
<a name="line-200"></a><span class='hs-definition'>finally</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span>
<a name="line-201"></a> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ computation to run first</span>
<a name="line-202"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-comment'>-- ^ computation to run afterward (even if an exception was</span>
<a name="line-203"></a> <span class='hs-comment'>-- raised)</span>
<a name="line-204"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- returns the value from the first computation</span>
<a name="line-205"></a><a name="finally"></a><span class='hs-definition'>thing</span> <span class='hs-varop'>`finally`</span> <span class='hs-varid'>after</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>block</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-206"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>unblock</span> <span class='hs-varid'>thing</span> <span class='hs-varop'>`onException`</span> <span class='hs-varid'>after</span>
<a name="line-207"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>after</span>
<a name="line-208"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>r</span>
<a name="line-209"></a>
<a name="line-210"></a><a name="bracketOnError"></a><span class='hs-comment'>-- | Like 'bracket', but only performs the final action if there was an</span>
<a name="line-211"></a><span class='hs-comment'>-- exception raised by the in-between computation.</span>
<a name="line-212"></a><span class='hs-definition'>bracketOnError</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>MonadCatchIO</span> <span class='hs-varid'>m</span>
<a name="line-213"></a> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ computation to run first (\"acquire resource\")</span>
<a name="line-214"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ computation to run last (\"release resource\")</span>
<a name="line-215"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ computation to run in-between</span>
<a name="line-216"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-- returns the value from the in-between computation</span>
<a name="line-217"></a><span class='hs-definition'>bracketOnError</span> <span class='hs-varid'>before</span> <span class='hs-varid'>after</span> <span class='hs-varid'>thing</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>block</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-218"></a> <span class='hs-varid'>a</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>before</span>
<a name="line-219"></a> <span class='hs-varid'>unblock</span> <span class='hs-layout'>(</span><span class='hs-varid'>thing</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-varop'>`onException`</span> <span class='hs-varid'>after</span> <span class='hs-varid'>a</span>
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