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<title>Control/Monad/Trans/Resource.hs</title>
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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE FlexibleContexts #-}</span>
<a name="line-2"></a><span class='hs-comment'>{-# LANGUAGE FlexibleInstances #-}</span>
<a name="line-3"></a><span class='hs-comment'>{-# LANGUAGE MultiParamTypeClasses #-}</span>
<a name="line-4"></a><span class='hs-comment'>{-# LANGUAGE UndecidableInstances #-}</span>
<a name="line-5"></a><span class='hs-comment'>{-# LANGUAGE TypeFamilies #-}</span>
<a name="line-6"></a><span class='hs-comment'>{-# LANGUAGE RankNTypes #-}</span>
<a name="line-7"></a><span class='hs-comment'>{-# LANGUAGE CPP #-}</span>
<a name="line-8"></a><span class='hs-comment'>{-# LANGUAGE DeriveDataTypeable #-}</span>
<a name="line-9"></a><span class='hs-comment'>-- | Allocate resources which are guaranteed to be released.</span>
<a name="line-10"></a><span class='hs-comment'>--</span>
<a name="line-11"></a><span class='hs-comment'>-- For more information, see <<a href="http://www.yesodweb.com/blog/2011/12/resourcet">http://www.yesodweb.com/blog/2011/12/resourcet</a>>.</span>
<a name="line-12"></a><span class='hs-comment'>--</span>
<a name="line-13"></a><span class='hs-comment'>-- One point to note: all register cleanup actions live in the base monad, not</span>
<a name="line-14"></a><span class='hs-comment'>-- the main monad. This allows both more efficient code, and for monads to be</span>
<a name="line-15"></a><span class='hs-comment'>-- transformed.</span>
<a name="line-16"></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'>Trans</span><span class='hs-varop'>.</span><span class='hs-conid'>Resource</span>
<a name="line-17"></a> <span class='hs-layout'>(</span> <span class='hs-comment'>-- * Data types</span>
<a name="line-18"></a> <span class='hs-conid'>ResourceT</span>
<a name="line-19"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ReleaseKey</span>
<a name="line-20"></a> <span class='hs-comment'>-- * Unwrap</span>
<a name="line-21"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>runResourceT</span>
<a name="line-22"></a> <span class='hs-comment'>-- * Resource allocation</span>
<a name="line-23"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>with</span>
<a name="line-24"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>withIO</span>
<a name="line-25"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>register</span>
<a name="line-26"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>release</span>
<a name="line-27"></a> <span class='hs-comment'>-- * Use references</span>
<a name="line-28"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>readRef</span>
<a name="line-29"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>writeRef</span>
<a name="line-30"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>newRef</span>
<a name="line-31"></a> <span class='hs-comment'>-- * Special actions</span>
<a name="line-32"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>resourceForkIO</span>
<a name="line-33"></a> <span class='hs-comment'>-- * Monad transformation</span>
<a name="line-34"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>transResourceT</span>
<a name="line-35"></a> <span class='hs-comment'>-- * A specific Exception transformer</span>
<a name="line-36"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-37"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>runExceptionT_</span>
<a name="line-38"></a> <span class='hs-comment'>-- * Type class/associated types</span>
<a name="line-39"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Resource</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-40"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-41"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ResourceIO</span>
<a name="line-42"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ResourceBaseIO</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-43"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ResourceThrow</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-44"></a> <span class='hs-comment'>-- ** Low-level</span>
<a name="line-45"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>HasRef</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-46"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-47"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>resourceActive</span>
<a name="line-48"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-49"></a>
<a name="line-50"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Typeable</span>
<a name="line-51"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IntMap</span> <span class='hs-layout'>(</span><span class='hs-conid'>IntMap</span><span class='hs-layout'>)</span>
<a name="line-52"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IntMap</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>IntMap</span>
<a name="line-53"></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-layout'>(</span><span class='hs-conid'>SomeException</span><span class='hs-layout'>,</span> <span class='hs-varid'>throw</span><span class='hs-layout'>,</span> <span class='hs-conid'>Exception</span><span class='hs-layout'>)</span>
<a name="line-54"></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'>Control</span>
<a name="line-55"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>MonadTransControl</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-56"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ComposeSt</span><span class='hs-layout'>,</span> <span class='hs-varid'>defaultLiftBaseWith</span><span class='hs-layout'>,</span> <span class='hs-varid'>defaultRestoreM</span>
<a name="line-57"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>liftBaseDiscard</span>
<a name="line-58"></a> <span class='hs-layout'>)</span>
<a name="line-59"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IORef</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>I</span>
<a name="line-60"></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'>Base</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadBase</span><span class='hs-layout'>,</span> <span class='hs-varid'>liftBase</span><span class='hs-layout'>)</span>
<a name="line-61"></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-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-62"></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'>Class</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadTrans</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-63"></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-keyglyph'>..</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-64"></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-layout'>(</span><span class='hs-varid'>liftM</span><span class='hs-layout'>)</span>
<a name="line-65"></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-keyword'>as</span> <span class='hs-conid'>E</span>
<a name="line-66"></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'>ST</span> <span class='hs-layout'>(</span><span class='hs-conid'>ST</span><span class='hs-layout'>,</span> <span class='hs-varid'>unsafeIOToST</span><span class='hs-layout'>)</span>
<a name="line-67"></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'>ST</span><span class='hs-varop'>.</span><span class='hs-conid'>Lazy</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Lazy</span>
<a name="line-68"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>STRef</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>S</span>
<a name="line-69"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>STRef</span><span class='hs-varop'>.</span><span class='hs-conid'>Lazy</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>SL</span>
<a name="line-70"></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-71"></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'>Lifted</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>L</span>
<a name="line-72"></a>
<a name="line-73"></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>
<a name="line-74"></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>
<a name="line-75"></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>
<a name="line-76"></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-conid'>Error</span><span class='hs-layout'>)</span>
<a name="line-77"></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>
<a name="line-78"></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>
<a name="line-79"></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>
<a name="line-80"></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>
<a name="line-81"></a>
<a name="line-82"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Word</span> <span class='hs-layout'>(</span><span class='hs-conid'>Word</span><span class='hs-layout'>)</span>
<a name="line-83"></a>
<a name="line-84"></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>
<a name="line-85"></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>
<a name="line-86"></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>
<a name="line-87"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Concurrent</span> <span class='hs-layout'>(</span><span class='hs-conid'>ThreadId</span><span class='hs-layout'>,</span> <span class='hs-varid'>forkIO</span><span class='hs-layout'>)</span>
<a name="line-88"></a>
<a name="line-89"></a><a name="newRef"></a><span class='hs-comment'>-- | Create a new reference.</span>
<a name="line-90"></a><span class='hs-definition'>newRef</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Ref</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-91"></a><span class='hs-definition'>newRef</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>.</span> <span class='hs-varid'>newRef'</span>
<a name="line-92"></a><span class='hs-comment'>{-# INLINE newRef #-}</span>
<a name="line-93"></a>
<a name="line-94"></a><a name="readRef"></a><span class='hs-comment'>-- | Read a value from a reference.</span>
<a name="line-95"></a><span class='hs-definition'>readRef</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Ref</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-96"></a><span class='hs-definition'>readRef</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>.</span> <span class='hs-varid'>readRef'</span>
<a name="line-97"></a><span class='hs-comment'>{-# INLINE readRef #-}</span>
<a name="line-98"></a>
<a name="line-99"></a><a name="writeRef"></a><span class='hs-comment'>-- | Write a value to a reference.</span>
<a name="line-100"></a><span class='hs-definition'>writeRef</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Ref</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-101"></a><span class='hs-definition'>writeRef</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>.</span> <span class='hs-varid'>writeRef'</span> <span class='hs-varid'>r</span>
<a name="line-102"></a><span class='hs-comment'>{-# INLINE writeRef #-}</span>
<a name="line-103"></a>
<a name="line-104"></a><a name="HasRef"></a><span class='hs-comment'>-- | A base monad which provides mutable references and some exception-safe way</span>
<a name="line-105"></a><a name="HasRef"></a><span class='hs-comment'>-- of interacting with them. For monads which cannot handle exceptions (e.g.,</span>
<a name="line-106"></a><a name="HasRef"></a><span class='hs-comment'>-- 'ST'), exceptions may be ignored. However, in such cases, scarce resources</span>
<a name="line-107"></a><a name="HasRef"></a><span class='hs-comment'>-- should /not/ be allocated in those monads, as exceptions may cause the</span>
<a name="line-108"></a><a name="HasRef"></a><span class='hs-comment'>-- cleanup functions to not run.</span>
<a name="line-109"></a><a name="HasRef"></a><span class='hs-comment'>--</span>
<a name="line-110"></a><a name="HasRef"></a><span class='hs-comment'>-- The instance for 'IO', however, is fully exception-safe.</span>
<a name="line-111"></a><a name="HasRef"></a><span class='hs-comment'>--</span>
<a name="line-112"></a><a name="HasRef"></a><span class='hs-comment'>-- Minimal complete definition: @Ref@, @newRef'@, @readRef'@ and @writeRef'@.</span>
<a name="line-113"></a><a name="HasRef"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>HasRef</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>where</span>
<a name="line-114"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Ref</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>::</span> <span class='hs-varop'>*</span> <span class='hs-keyglyph'>-></span> <span class='hs-varop'>*</span>
<a name="line-115"></a> <span class='hs-varid'>newRef'</span> <span class='hs-keyglyph'>::</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'>Ref</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-116"></a> <span class='hs-varid'>readRef'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ref</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-117"></a> <span class='hs-varid'>writeRef'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ref</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-118"></a>
<a name="line-119"></a> <span class='hs-comment'>-- | For monads supporting multi-threaded access (e.g., @IO@), this much be</span>
<a name="line-120"></a> <span class='hs-comment'>-- an atomic modification.</span>
<a name="line-121"></a> <span class='hs-varid'>atomicModifyRef'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Ref</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-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-122"></a> <span class='hs-varid'>atomicModifyRef'</span> <span class='hs-varid'>sa</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-123"></a> <span class='hs-varid'>a0</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>readRef'</span> <span class='hs-varid'>sa</span>
<a name="line-124"></a> <span class='hs-keyword'>let</span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a0</span>
<a name="line-125"></a> <span class='hs-varid'>writeRef'</span> <span class='hs-varid'>sa</span> <span class='hs-varid'>a</span>
<a name="line-126"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>b</span>
<a name="line-127"></a>
<a name="line-128"></a> <span class='hs-varid'>mask</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-keyword'>forall</span> <span class='hs-varid'>a</span><span class='hs-varop'>.</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><span class='hs-layout'>)</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-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-129"></a> <span class='hs-varid'>mask</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>id</span>
<a name="line-130"></a>
<a name="line-131"></a> <span class='hs-varid'>mask_</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-132"></a> <span class='hs-varid'>mask_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mask</span> <span class='hs-varop'>.</span> <span class='hs-varid'>const</span>
<a name="line-133"></a>
<a name="line-134"></a> <span class='hs-varid'>try</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-conid'>SomeException</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-135"></a> <span class='hs-varid'>try</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftM</span> <span class='hs-conid'>Right</span>
<a name="line-136"></a>
<a name="line-137"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>HasRef</span> <span class='hs-conid'>IO</span> <span class='hs-keyword'>where</span>
<a name="line-138"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Ref</span> <span class='hs-conid'>IO</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-conid'>IORef</span>
<a name="line-139"></a> <span class='hs-varid'>newRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-varid'>newIORef</span>
<a name="line-140"></a> <span class='hs-comment'>{-# INLINE newRef' #-}</span>
<a name="line-141"></a> <span class='hs-varid'>atomicModifyRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-varid'>atomicModifyIORef</span>
<a name="line-142"></a> <span class='hs-comment'>{-# INLINE atomicModifyRef' #-}</span>
<a name="line-143"></a> <span class='hs-varid'>readRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-varid'>readIORef</span>
<a name="line-144"></a> <span class='hs-comment'>{-# INLINE readRef' #-}</span>
<a name="line-145"></a> <span class='hs-varid'>writeRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>I</span><span class='hs-varop'>.</span><span class='hs-varid'>writeIORef</span>
<a name="line-146"></a> <span class='hs-comment'>{-# INLINE writeRef' #-}</span>
<a name="line-147"></a> <span class='hs-varid'>mask</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>mask</span>
<a name="line-148"></a> <span class='hs-comment'>{-# INLINE mask #-}</span>
<a name="line-149"></a> <span class='hs-varid'>mask_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>mask_</span>
<a name="line-150"></a> <span class='hs-comment'>{-# INLINE mask_ #-}</span>
<a name="line-151"></a> <span class='hs-varid'>try</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>try</span>
<a name="line-152"></a> <span class='hs-comment'>{-# INLINE try #-}</span>
<a name="line-153"></a>
<a name="line-154"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>HasRef</span> <span class='hs-layout'>(</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-155"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Ref</span> <span class='hs-layout'>(</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>S</span><span class='hs-varop'>.</span><span class='hs-conid'>STRef</span> <span class='hs-varid'>s</span>
<a name="line-156"></a> <span class='hs-varid'>newRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>S</span><span class='hs-varop'>.</span><span class='hs-varid'>newSTRef</span>
<a name="line-157"></a> <span class='hs-varid'>readRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>S</span><span class='hs-varop'>.</span><span class='hs-varid'>readSTRef</span>
<a name="line-158"></a> <span class='hs-varid'>writeRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>S</span><span class='hs-varop'>.</span><span class='hs-varid'>writeSTRef</span>
<a name="line-159"></a>
<a name="line-160"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>HasRef</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-161"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Ref</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>SL</span><span class='hs-varop'>.</span><span class='hs-conid'>STRef</span> <span class='hs-varid'>s</span>
<a name="line-162"></a> <span class='hs-varid'>newRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>SL</span><span class='hs-varop'>.</span><span class='hs-varid'>newSTRef</span>
<a name="line-163"></a> <span class='hs-varid'>readRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>SL</span><span class='hs-varop'>.</span><span class='hs-varid'>readSTRef</span>
<a name="line-164"></a> <span class='hs-varid'>writeRef'</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>SL</span><span class='hs-varop'>.</span><span class='hs-varid'>writeSTRef</span>
<a name="line-165"></a>
<a name="line-166"></a><a name="Resource"></a><span class='hs-comment'>-- | A 'Monad' with a base that has mutable references, and allows some way to</span>
<a name="line-167"></a><a name="Resource"></a><span class='hs-comment'>-- run base actions and clean up properly.</span>
<a name="line-168"></a><a name="Resource"></a><span class='hs-keyword'>class</span> <span class='hs-layout'>(</span><span class='hs-conid'>HasRef</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>where</span>
<a name="line-169"></a> <span class='hs-comment'>-- | The base monad for the current monad stack. This will usually be @IO@</span>
<a name="line-170"></a> <span class='hs-comment'>-- or @ST@.</span>
<a name="line-171"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Base</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>::</span> <span class='hs-varop'>*</span> <span class='hs-keyglyph'>-></span> <span class='hs-varop'>*</span>
<a name="line-172"></a>
<a name="line-173"></a> <span class='hs-comment'>-- | Run some action in the @Base@ monad. This function corresponds to</span>
<a name="line-174"></a> <span class='hs-comment'>-- 'liftBase', but due to various type issues, we need to have our own</span>
<a name="line-175"></a> <span class='hs-comment'>-- version here.</span>
<a name="line-176"></a> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Base</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-177"></a>
<a name="line-178"></a> <span class='hs-comment'>-- | Guarantee that some initialization and cleanup code is called before</span>
<a name="line-179"></a> <span class='hs-comment'>-- and after some action. Note that the initialization and cleanup lives in</span>
<a name="line-180"></a> <span class='hs-comment'>-- the base monad, while the body is in the top monad.</span>
<a name="line-181"></a> <span class='hs-varid'>resourceBracket_</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Base</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span> <span class='hs-comment'>-- ^ init</span>
<a name="line-182"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Base</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span> <span class='hs-comment'>-- ^ cleanup</span>
<a name="line-183"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span> <span class='hs-comment'>-- ^ body</span>
<a name="line-184"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>c</span>
<a name="line-185"></a>
<a name="line-186"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Resource</span> <span class='hs-conid'>IO</span> <span class='hs-keyword'>where</span>
<a name="line-187"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Base</span> <span class='hs-conid'>IO</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>IO</span>
<a name="line-188"></a> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>id</span>
<a name="line-189"></a> <span class='hs-varid'>resourceBracket_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>bracket_</span>
<a name="line-190"></a>
<a name="line-191"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Resource</span> <span class='hs-layout'>(</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-192"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Base</span> <span class='hs-layout'>(</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ST</span> <span class='hs-varid'>s</span>
<a name="line-193"></a> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>id</span>
<a name="line-194"></a> <span class='hs-varid'>resourceBracket_</span> <span class='hs-varid'>ma</span> <span class='hs-varid'>mb</span> <span class='hs-varid'>mc</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-195"></a> <span class='hs-varid'>ma</span>
<a name="line-196"></a> <span class='hs-varid'>c</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>mc</span>
<a name="line-197"></a> <span class='hs-varid'>mb</span>
<a name="line-198"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>c</span>
<a name="line-199"></a>
<a name="line-200"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Resource</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-201"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Base</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span>
<a name="line-202"></a> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>id</span>
<a name="line-203"></a> <span class='hs-varid'>resourceBracket_</span> <span class='hs-varid'>ma</span> <span class='hs-varid'>mb</span> <span class='hs-varid'>mc</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-204"></a> <span class='hs-varid'>ma</span>
<a name="line-205"></a> <span class='hs-varid'>c</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>mc</span>
<a name="line-206"></a> <span class='hs-varid'>mb</span>
<a name="line-207"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>c</span>
<a name="line-208"></a>
<a name="line-209"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadTransControl</span> <span class='hs-varid'>t</span><span class='hs-layout'>,</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-210"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Resource</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-211"></a> <span class='hs-keyword'>type</span> <span class='hs-conid'>Base</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Base</span> <span class='hs-varid'>m</span>
<a name="line-212"></a>
<a name="line-213"></a> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>resourceLiftBase</span>
<a name="line-214"></a> <span class='hs-varid'>resourceBracket_</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-varid'>c</span> <span class='hs-keyglyph'>=</span>
<a name="line-215"></a> <span class='hs-varid'>control'</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>run</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>resourceBracket_</span> <span class='hs-varid'>a</span> <span class='hs-varid'>b</span> <span class='hs-layout'>(</span><span class='hs-varid'>run</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span>
<a name="line-216"></a> <span class='hs-keyword'>where</span>
<a name="line-217"></a> <span class='hs-varid'>control'</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftWith</span> <span class='hs-varid'>f</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>restoreT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span>
<a name="line-218"></a>
<a name="line-219"></a><a name="ResourceUnsafeIO"></a><span class='hs-comment'>-- | A 'Resource' based on some monad which allows running of some 'IO'</span>
<a name="line-220"></a><a name="ResourceUnsafeIO"></a><span class='hs-comment'>-- actions, via unsafe calls. This applies to 'IO' and 'ST', for instance.</span>
<a name="line-221"></a><a name="ResourceUnsafeIO"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>where</span>
<a name="line-222"></a> <span class='hs-varid'>unsafeFromIO</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-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-223"></a>
<a name="line-224"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-conid'>IO</span> <span class='hs-keyword'>where</span>
<a name="line-225"></a> <span class='hs-varid'>unsafeFromIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>id</span>
<a name="line-226"></a>
<a name="line-227"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-228"></a> <span class='hs-varid'>unsafeFromIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unsafeIOToST</span>
<a name="line-229"></a>
<a name="line-230"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-conid'>ST</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-231"></a> <span class='hs-varid'>unsafeFromIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Lazy</span><span class='hs-varop'>.</span><span class='hs-varid'>unsafeIOToST</span>
<a name="line-232"></a>
<a name="line-233"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadTransControl</span> <span class='hs-varid'>t</span><span class='hs-layout'>,</span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-234"></a> <span class='hs-varid'>unsafeFromIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>unsafeFromIO</span>
<a name="line-235"></a>
<a name="line-236"></a><a name="ResourceBaseIO"></a><span class='hs-comment'>-- | A helper class for 'ResourceIO', stating that the base monad provides @IO@</span>
<a name="line-237"></a><a name="ResourceBaseIO"></a><span class='hs-comment'>-- actions.</span>
<a name="line-238"></a><a name="ResourceBaseIO"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>ResourceBaseIO</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>where</span>
<a name="line-239"></a> <span class='hs-varid'>safeFromIOBase</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-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-240"></a>
<a name="line-241"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ResourceBaseIO</span> <span class='hs-conid'>IO</span> <span class='hs-keyword'>where</span>
<a name="line-242"></a> <span class='hs-varid'>safeFromIOBase</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>id</span>
<a name="line-243"></a>
<a name="line-244"></a><a name="ResourceIO"></a><span class='hs-comment'>-- | A 'Resource' which can safely run 'IO' calls.</span>
<a name="line-245"></a><a name="ResourceIO"></a><span class='hs-keyword'>class</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceBaseIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>ResourceUnsafeIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>ResourceThrow</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span>
<a name="line-246"></a> <span class='hs-conid'>MonadIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-conid'>IO</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-247"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceIO</span> <span class='hs-varid'>m</span>
<a name="line-248"></a>
<a name="line-249"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ResourceIO</span> <span class='hs-conid'>IO</span>
<a name="line-250"></a>
<a name="line-251"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadTransControl</span> <span class='hs-varid'>t</span><span class='hs-layout'>,</span> <span class='hs-conid'>ResourceIO</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>ResourceThrow</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span>
<a name="line-252"></a> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-253"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>t</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-254"></a>
<a name="line-255"></a><a name="ReleaseKey"></a><span class='hs-comment'>-- | A lookup key for a specific release action. This value is returned by</span>
<a name="line-256"></a><a name="ReleaseKey"></a><span class='hs-comment'>-- 'register', 'with' and 'withIO', and is passed to 'release'.</span>
<a name="line-257"></a><a name="ReleaseKey"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>ReleaseKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ReleaseKey</span> <span class='hs-conid'>Int</span>
<a name="line-258"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Typeable</span>
<a name="line-259"></a>
<a name="line-260"></a><a name="RefCount"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>RefCount</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Word</span>
<a name="line-261"></a><a name="NextKey"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>NextKey</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Int</span>
<a name="line-262"></a>
<a name="line-263"></a><a name="ReleaseMap"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>base</span> <span class='hs-keyglyph'>=</span>
<a name="line-264"></a> <span class='hs-conid'>ReleaseMap</span> <span class='hs-varop'>!</span><span class='hs-conid'>NextKey</span> <span class='hs-varop'>!</span><span class='hs-conid'>RefCount</span> <span class='hs-varop'>!</span><span class='hs-layout'>(</span><span class='hs-conid'>IntMap</span> <span class='hs-layout'>(</span><span class='hs-varid'>base</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-265"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>ReleaseMapClosed</span>
<a name="line-266"></a>
<a name="line-267"></a><a name="ResourceT"></a><span class='hs-comment'>-- | The Resource transformer. This transformer keeps track of all registered</span>
<a name="line-268"></a><a name="ResourceT"></a><span class='hs-comment'>-- actions, and calls them upon exit (via 'runResourceT'). Actions may be</span>
<a name="line-269"></a><a name="ResourceT"></a><span class='hs-comment'>-- registered via 'register', or resources may be allocated atomically via</span>
<a name="line-270"></a><a name="ResourceT"></a><span class='hs-comment'>-- 'with' or 'withIO'. The with functions correspond closely to @bracket@.</span>
<a name="line-271"></a><a name="ResourceT"></a><span class='hs-comment'>--</span>
<a name="line-272"></a><a name="ResourceT"></a><span class='hs-comment'>-- Releasing may be performed before exit via the 'release' function. This is a</span>
<a name="line-273"></a><a name="ResourceT"></a><span class='hs-comment'>-- highly recommended optimization, as it will ensure that scarce resources are</span>
<a name="line-274"></a><a name="ResourceT"></a><span class='hs-comment'>-- freed early. Note that calling @release@ will deregister the action, so that</span>
<a name="line-275"></a><a name="ResourceT"></a><span class='hs-comment'>-- a release action will only ever be called once.</span>
<a name="line-276"></a><a name="ResourceT"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span>
<a name="line-277"></a> <span class='hs-conid'>ResourceT</span> <span class='hs-layout'>(</span><span class='hs-conid'>Ref</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</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-layout'>)</span>
<a name="line-278"></a>
<a name="line-279"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Typeable1</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Typeable1</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-280"></a> <span class='hs-varid'>typeOf1</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>goType</span> <span class='hs-varid'>undefined</span>
<a name="line-281"></a> <span class='hs-keyword'>where</span>
<a name="line-282"></a> <span class='hs-varid'>goType</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Typeable1</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-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>TypeRep</span>
<a name="line-283"></a> <span class='hs-varid'>goType</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span>
<a name="line-284"></a> <span class='hs-varid'>mkTyConApp</span>
<a name="line-285"></a> <span class='hs-layout'>(</span><span class='hs-varid'>mkTyCon</span> <span class='hs-str'>"Control.Monad.Trans.Resource.ResourceT"</span><span class='hs-layout'>)</span>
<a name="line-286"></a> <span class='hs-keyglyph'>[</span> <span class='hs-varid'>typeOf1</span> <span class='hs-varid'>m</span>
<a name="line-287"></a> <span class='hs-keyglyph'>]</span>
<a name="line-288"></a>
<a name="line-289"></a><a name="with"></a><span class='hs-comment'>-- | Perform some allocation, and automatically register a cleanup action.</span>
<a name="line-290"></a><span class='hs-comment'>--</span>
<a name="line-291"></a><span class='hs-comment'>-- If you are performing an @IO@ action, it will likely be easier to use the</span>
<a name="line-292"></a><span class='hs-comment'>-- 'withIO' function, which handles types more cleanly.</span>
<a name="line-293"></a><span class='hs-definition'>with</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span>
<a name="line-294"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Base</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ allocate</span>
<a name="line-295"></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-conid'>Base</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ free resource</span>
<a name="line-296"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseKey</span><span class='hs-layout'>,</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-297"></a><span class='hs-definition'>with</span> <span class='hs-varid'>acquire</span> <span class='hs-varid'>rel</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>istate</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mask</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>restore</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-298"></a> <span class='hs-varid'>a</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>restore</span> <span class='hs-varid'>acquire</span>
<a name="line-299"></a> <span class='hs-varid'>key</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>register'</span> <span class='hs-varid'>istate</span> <span class='hs-varop'>$</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>a</span>
<a name="line-300"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>key</span><span class='hs-layout'>,</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-301"></a>
<a name="line-302"></a><a name="withIO"></a><span class='hs-comment'>-- | Same as 'with', but explicitly uses @IO@ as a base.</span>
<a name="line-303"></a><span class='hs-definition'>withIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ResourceIO</span> <span class='hs-varid'>m</span>
<a name="line-304"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ allocate</span>
<a name="line-305"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-comment'>-- ^ free resource</span>
<a name="line-306"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseKey</span><span class='hs-layout'>,</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-307"></a><span class='hs-definition'>withIO</span> <span class='hs-varid'>acquire</span> <span class='hs-varid'>rel</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>istate</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>mask</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>restore</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-308"></a> <span class='hs-varid'>a</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>restore</span> <span class='hs-varop'>$</span> <span class='hs-varid'>safeFromIOBase</span> <span class='hs-varid'>acquire</span>
<a name="line-309"></a> <span class='hs-varid'>key</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>register'</span> <span class='hs-varid'>istate</span> <span class='hs-varop'>$</span> <span class='hs-varid'>safeFromIOBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>safeFromIOBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>a</span>
<a name="line-310"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>key</span><span class='hs-layout'>,</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-311"></a>
<a name="line-312"></a><a name="register"></a><span class='hs-comment'>-- | Register some action that will be called precisely once, either when</span>
<a name="line-313"></a><span class='hs-comment'>-- 'runResourceT' is called, or when the 'ReleaseKey' is passed to 'release'.</span>
<a name="line-314"></a><span class='hs-definition'>register</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span>
<a name="line-315"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Base</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-316"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-conid'>ReleaseKey</span>
<a name="line-317"></a><span class='hs-definition'>register</span> <span class='hs-varid'>rel</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>istate</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>register'</span> <span class='hs-varid'>istate</span> <span class='hs-varid'>rel</span>
<a name="line-318"></a>
<a name="line-319"></a><a name="register'"></a><span class='hs-definition'>register'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>HasRef</span> <span class='hs-varid'>base</span>
<a name="line-320"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Ref</span> <span class='hs-varid'>base</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>base</span><span class='hs-layout'>)</span>
<a name="line-321"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>base</span> <span class='hs-conid'>()</span>
<a name="line-322"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>base</span> <span class='hs-conid'>ReleaseKey</span>
<a name="line-323"></a><span class='hs-definition'>register'</span> <span class='hs-varid'>istate</span> <span class='hs-varid'>rel</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>atomicModifyRef'</span> <span class='hs-varid'>istate</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>rm</span> <span class='hs-keyglyph'>-></span>
<a name="line-324"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>rm</span> <span class='hs-keyword'>of</span>
<a name="line-325"></a> <span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>key</span> <span class='hs-varid'>rf</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>-></span>
<a name="line-326"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>ReleaseMap</span> <span class='hs-layout'>(</span><span class='hs-varid'>key</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>rf</span> <span class='hs-layout'>(</span><span class='hs-conid'>IntMap</span><span class='hs-varop'>.</span><span class='hs-varid'>insert</span> <span class='hs-varid'>key</span> <span class='hs-varid'>rel</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-327"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>ReleaseKey</span> <span class='hs-varid'>key</span>
<a name="line-328"></a> <span class='hs-layout'>)</span>
<a name="line-329"></a> <span class='hs-conid'>ReleaseMapClosed</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>throw</span> <span class='hs-varop'>$</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-str'>"register'"</span>
<a name="line-330"></a>
<a name="line-331"></a><a name="InvalidAccess"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-layout'>{</span> <span class='hs-varid'>functionName</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-layout'>}</span>
<a name="line-332"></a> <span class='hs-keyword'>deriving</span> <span class='hs-conid'>Typeable</span>
<a name="line-333"></a>
<a name="line-334"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Show</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-keyword'>where</span>
<a name="line-335"></a> <span class='hs-varid'>show</span> <span class='hs-layout'>(</span><span class='hs-conid'>InvalidAccess</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>concat</span>
<a name="line-336"></a> <span class='hs-keyglyph'>[</span> <span class='hs-str'>"Control.Monad.Trans.Resource."</span>
<a name="line-337"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>f</span>
<a name="line-338"></a> <span class='hs-layout'>,</span> <span class='hs-str'>": The mutable state is being accessed after cleanup. Please contact the maintainers."</span>
<a name="line-339"></a> <span class='hs-keyglyph'>]</span>
<a name="line-340"></a>
<a name="line-341"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Exception</span> <span class='hs-conid'>InvalidAccess</span>
<a name="line-342"></a>
<a name="line-343"></a><a name="release"></a><span class='hs-comment'>-- | Call a release action early, and deregister it from the list of cleanup</span>
<a name="line-344"></a><span class='hs-comment'>-- actions to be performed.</span>
<a name="line-345"></a><span class='hs-definition'>release</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span>
<a name="line-346"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ReleaseKey</span>
<a name="line-347"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-348"></a><span class='hs-definition'>release</span> <span class='hs-varid'>rk</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>istate</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>release'</span> <span class='hs-varid'>istate</span> <span class='hs-varid'>rk</span>
<a name="line-349"></a>
<a name="line-350"></a><a name="release'"></a><span class='hs-definition'>release'</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>HasRef</span> <span class='hs-varid'>base</span>
<a name="line-351"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Ref</span> <span class='hs-varid'>base</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>base</span><span class='hs-layout'>)</span>
<a name="line-352"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ReleaseKey</span>
<a name="line-353"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>base</span> <span class='hs-conid'>()</span>
<a name="line-354"></a><span class='hs-definition'>release'</span> <span class='hs-varid'>istate</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseKey</span> <span class='hs-varid'>key</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mask</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>restore</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-355"></a> <span class='hs-varid'>maction</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>atomicModifyRef'</span> <span class='hs-varid'>istate</span> <span class='hs-varid'>lookupAction</span>
<a name="line-356"></a> <span class='hs-varid'>maybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>restore</span> <span class='hs-varid'>maction</span>
<a name="line-357"></a> <span class='hs-keyword'>where</span>
<a name="line-358"></a> <span class='hs-varid'>lookupAction</span> <span class='hs-varid'>rm</span><span class='hs-keyglyph'>@</span><span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>next</span> <span class='hs-varid'>rf</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span>
<a name="line-359"></a> <span class='hs-keyword'>case</span> <span class='hs-conid'>IntMap</span><span class='hs-varop'>.</span><span class='hs-varid'>lookup</span> <span class='hs-varid'>key</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>of</span>
<a name="line-360"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-varid'>rm</span><span class='hs-layout'>,</span> <span class='hs-conid'>Nothing</span><span class='hs-layout'>)</span>
<a name="line-361"></a> <span class='hs-conid'>Just</span> <span class='hs-varid'>action</span> <span class='hs-keyglyph'>-></span>
<a name="line-362"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>next</span> <span class='hs-varid'>rf</span> <span class='hs-varop'>$</span> <span class='hs-conid'>IntMap</span><span class='hs-varop'>.</span><span class='hs-varid'>delete</span> <span class='hs-varid'>key</span> <span class='hs-varid'>m</span>
<a name="line-363"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>action</span>
<a name="line-364"></a> <span class='hs-layout'>)</span>
<a name="line-365"></a> <span class='hs-varid'>lookupAction</span> <span class='hs-conid'>ReleaseMapClosed</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>throw</span> <span class='hs-varop'>$</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-str'>"release'"</span>
<a name="line-366"></a>
<a name="line-367"></a><a name="stateAlloc"></a><span class='hs-definition'>stateAlloc</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>HasRef</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Ref</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-368"></a><span class='hs-definition'>stateAlloc</span> <span class='hs-varid'>istate</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-369"></a> <span class='hs-varid'>atomicModifyRef'</span> <span class='hs-varid'>istate</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>rm</span> <span class='hs-keyglyph'>-></span>
<a name="line-370"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>rm</span> <span class='hs-keyword'>of</span>
<a name="line-371"></a> <span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>nk</span> <span class='hs-varid'>rf</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>-></span>
<a name="line-372"></a> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>nk</span> <span class='hs-layout'>(</span><span class='hs-varid'>rf</span> <span class='hs-varop'>+</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-373"></a> <span class='hs-conid'>ReleaseMapClosed</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>throw</span> <span class='hs-varop'>$</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-str'>"stateAlloc"</span>
<a name="line-374"></a>
<a name="line-375"></a><a name="stateCleanup"></a><span class='hs-definition'>stateCleanup</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>HasRef</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Ref</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span>
<a name="line-376"></a><span class='hs-definition'>stateCleanup</span> <span class='hs-varid'>istate</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mask_</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-377"></a> <span class='hs-varid'>mm</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>atomicModifyRef'</span> <span class='hs-varid'>istate</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>rm</span> <span class='hs-keyglyph'>-></span>
<a name="line-378"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>rm</span> <span class='hs-keyword'>of</span>
<a name="line-379"></a> <span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>nk</span> <span class='hs-varid'>rf</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>-></span>
<a name="line-380"></a> <span class='hs-keyword'>let</span> <span class='hs-varid'>rf'</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>rf</span> <span class='hs-comment'>-</span> <span class='hs-num'>1</span>
<a name="line-381"></a> <span class='hs-keyword'>in</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>rf'</span> <span class='hs-varop'>==</span> <span class='hs-varid'>minBound</span>
<a name="line-382"></a> <span class='hs-keyword'>then</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMapClosed</span><span class='hs-layout'>,</span> <span class='hs-conid'>Just</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-383"></a> <span class='hs-keyword'>else</span> <span class='hs-layout'>(</span><span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>nk</span> <span class='hs-varid'>rf'</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>Nothing</span><span class='hs-layout'>)</span>
<a name="line-384"></a> <span class='hs-conid'>ReleaseMapClosed</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>throw</span> <span class='hs-varop'>$</span> <span class='hs-conid'>InvalidAccess</span> <span class='hs-str'>"stateCleanup"</span>
<a name="line-385"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>mm</span> <span class='hs-keyword'>of</span>
<a name="line-386"></a> <span class='hs-conid'>Just</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>-></span>
<a name="line-387"></a> <span class='hs-varid'>mapM_</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>x</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>try</span> <span class='hs-varid'>x</span> <span class='hs-varop'>>></span> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-conid'>IntMap</span><span class='hs-varop'>.</span><span class='hs-varid'>elems</span> <span class='hs-varid'>m</span>
<a name="line-388"></a> <span class='hs-conid'>Nothing</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>()</span>
<a name="line-389"></a>
<a name="line-390"></a><a name="runResourceT"></a><span class='hs-comment'>-- | Unwrap a 'ResourceT' transformer, and call all registered release actions.</span>
<a name="line-391"></a><span class='hs-comment'>--</span>
<a name="line-392"></a><span class='hs-comment'>-- Note that there is some reference counting involved due to 'resourceForkIO'.</span>
<a name="line-393"></a><span class='hs-comment'>-- If multiple threads are sharing the same collection of resources, only the</span>
<a name="line-394"></a><span class='hs-comment'>-- last call to @runResourceT@ will deallocate the resources.</span>
<a name="line-395"></a><span class='hs-definition'>runResourceT</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-396"></a><span class='hs-definition'>runResourceT</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-397"></a> <span class='hs-varid'>istate</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>newRef'</span>
<a name="line-398"></a> <span class='hs-varop'>$</span> <span class='hs-conid'>ReleaseMap</span> <span class='hs-varid'>minBound</span> <span class='hs-varid'>minBound</span> <span class='hs-conid'>IntMap</span><span class='hs-varop'>.</span><span class='hs-varid'>empty</span>
<a name="line-399"></a> <span class='hs-varid'>resourceBracket_</span>
<a name="line-400"></a> <span class='hs-layout'>(</span><span class='hs-varid'>stateAlloc</span> <span class='hs-varid'>istate</span><span class='hs-layout'>)</span>
<a name="line-401"></a> <span class='hs-layout'>(</span><span class='hs-varid'>stateCleanup</span> <span class='hs-varid'>istate</span><span class='hs-layout'>)</span>
<a name="line-402"></a> <span class='hs-layout'>(</span><span class='hs-varid'>r</span> <span class='hs-varid'>istate</span><span class='hs-layout'>)</span>
<a name="line-403"></a>
<a name="line-404"></a><a name="transResourceT"></a><span class='hs-comment'>-- | Transform the monad a @ResourceT@ lives in. This is most often used to</span>
<a name="line-405"></a><span class='hs-comment'>-- strip or add new transformers to a stack, e.g. to run a @ReaderT@. Note that</span>
<a name="line-406"></a><span class='hs-comment'>-- the original and new monad must both have the same 'Base' monad.</span>
<a name="line-407"></a><span class='hs-definition'>transResourceT</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>~</span> <span class='hs-conid'>Base</span> <span class='hs-varid'>n</span><span class='hs-layout'>)</span>
<a name="line-408"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>n</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-409"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-410"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>n</span> <span class='hs-varid'>b</span>
<a name="line-411"></a><span class='hs-definition'>transResourceT</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>mx</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>mx</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-412"></a>
<a name="line-413"></a><span class='hs-comment'>-------- All of our monad et al instances</span>
<a name="line-414"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Functor</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-415"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</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'>liftM</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-416"></a>
<a name="line-417"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-418"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>const</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span>
<a name="line-419"></a> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>mf</span> <span class='hs-varop'><*></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>ma</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-420"></a> <span class='hs-varid'>f</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>mf</span> <span class='hs-varid'>r</span>
<a name="line-421"></a> <span class='hs-varid'>a</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>ma</span> <span class='hs-varid'>r</span>
<a name="line-422"></a> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>a</span>
<a name="line-423"></a>
<a name="line-424"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-425"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pure</span>
<a name="line-426"></a> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>ma</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span>
<a name="line-427"></a> <span class='hs-conid'>ResourceT</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'>ma</span> <span class='hs-varid'>r</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>flip</span> <span class='hs-varid'>un</span> <span class='hs-varid'>r</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span>
<a name="line-428"></a> <span class='hs-keyword'>where</span>
<a name="line-429"></a> <span class='hs-varid'>un</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>x</span>
<a name="line-430"></a>
<a name="line-431"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadTrans</span> <span class='hs-conid'>ResourceT</span> <span class='hs-keyword'>where</span>
<a name="line-432"></a> <span class='hs-varid'>lift</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>const</span>
<a name="line-433"></a>
<a name="line-434"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-435"></a> <span class='hs-varid'>liftIO</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>liftIO</span>
<a name="line-436"></a>
<a name="line-437"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadBase</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadBase</span> <span class='hs-varid'>b</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-438"></a> <span class='hs-varid'>liftBase</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>liftBase</span>
<a name="line-439"></a>
<a name="line-440"></a><span class='hs-comment'>{-
<a name="line-441"></a>instance MonadTransControl ResourceT where
<a name="line-442"></a> newtype StT ResourceT a = StReader {unStReader :: a}
<a name="line-443"></a> liftWith f = ResourceT $ \r -> f $ \(ResourceT t) -> liftM StReader $ t r
<a name="line-444"></a> restoreT = ResourceT . const . liftM unStReader
<a name="line-445"></a> {-# INLINE liftWith #-}
<a name="line-446"></a> {-# INLINE restoreT #-}
<a name="line-447"></a>-}</span>
<a name="line-448"></a>
<a name="line-449"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-varid'>b</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-450"></a> <span class='hs-keyword'>newtype</span> <span class='hs-conid'>StM</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>StMT</span> <span class='hs-layout'>(</span><span class='hs-conid'>StM</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-451"></a> <span class='hs-varid'>liftBaseWith</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>reader</span> <span class='hs-keyglyph'>-></span>
<a name="line-452"></a> <span class='hs-varid'>liftBaseWith</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>runInBase</span> <span class='hs-keyglyph'>-></span>
<a name="line-453"></a> <span class='hs-varid'>f</span> <span class='hs-varop'>$</span> <span class='hs-varid'>liftM</span> <span class='hs-conid'>StMT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runInBase</span> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>\</span><span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>r</span> <span class='hs-varid'>reader</span><span class='hs-layout'>)</span>
<a name="line-454"></a> <span class='hs-varid'>restoreM</span> <span class='hs-layout'>(</span><span class='hs-conid'>StMT</span> <span class='hs-varid'>base</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>const</span> <span class='hs-varop'>$</span> <span class='hs-varid'>restoreM</span> <span class='hs-varid'>base</span>
<a name="line-455"></a>
<a name="line-456"></a><a name="ExceptionT"></a><span class='hs-comment'>-- | The express purpose of this transformer is to allow the 'ST' monad to</span>
<a name="line-457"></a><a name="ExceptionT"></a><span class='hs-comment'>-- catch exceptions via the 'ResourceThrow' typeclass.</span>
<a name="line-458"></a><a name="ExceptionT"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-layout'>{</span> <span class='hs-varid'>runExceptionT</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-conid'>SomeException</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-layout'>}</span>
<a name="line-459"></a>
<a name="line-460"></a><a name="runExceptionT_"></a><span class='hs-comment'>-- | Same as 'runExceptionT', but immediately 'E.throw' any exception returned.</span>
<a name="line-461"></a><span class='hs-definition'>runExceptionT_</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ExceptionT</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-462"></a><span class='hs-definition'>runExceptionT_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftM</span> <span class='hs-layout'>(</span><span class='hs-varid'>either</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>throw</span> <span class='hs-varid'>id</span><span class='hs-layout'>)</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runExceptionT</span>
<a name="line-463"></a>
<a name="line-464"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Functor</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-465"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-varid'>liftM</span> <span class='hs-varop'>.</span> <span class='hs-varid'>fmap</span><span class='hs-layout'>)</span> <span class='hs-varid'>f</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runExceptionT</span>
<a name="line-466"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-467"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-conid'>Right</span>
<a name="line-468"></a> <span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>mf</span> <span class='hs-varop'><*></span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>ma</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-469"></a> <span class='hs-varid'>ef</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>mf</span>
<a name="line-470"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>ef</span> <span class='hs-keyword'>of</span>
<a name="line-471"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>e</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'>e</span><span class='hs-layout'>)</span>
<a name="line-472"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-473"></a> <span class='hs-varid'>ea</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>ma</span>
<a name="line-474"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>ea</span> <span class='hs-keyword'>of</span>
<a name="line-475"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>e</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'>e</span><span class='hs-layout'>)</span>
<a name="line-476"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>x</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-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-477"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Monad</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-478"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>pure</span>
<a name="line-479"></a> <span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>ma</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-480"></a> <span class='hs-varid'>ea</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>ma</span>
<a name="line-481"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>ea</span> <span class='hs-keyword'>of</span>
<a name="line-482"></a> <span class='hs-conid'>Left</span> <span class='hs-varid'>e</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'>e</span><span class='hs-layout'>)</span>
<a name="line-483"></a> <span class='hs-conid'>Right</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runExceptionT</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-484"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadBase</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadBase</span> <span class='hs-varid'>b</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-485"></a> <span class='hs-varid'>liftBase</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lift</span> <span class='hs-varop'>.</span> <span class='hs-varid'>liftBase</span>
<a name="line-486"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadTrans</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-keyword'>where</span>
<a name="line-487"></a> <span class='hs-varid'>lift</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>liftM</span> <span class='hs-conid'>Right</span>
<a name="line-488"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadTransControl</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-keyword'>where</span>
<a name="line-489"></a> <span class='hs-keyword'>newtype</span> <span class='hs-conid'>StT</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>StExc</span> <span class='hs-layout'>{</span> <span class='hs-varid'>unStExc</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Either</span> <span class='hs-conid'>SomeException</span> <span class='hs-varid'>a</span> <span class='hs-layout'>}</span>
<a name="line-490"></a> <span class='hs-varid'>liftWith</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>$</span> <span class='hs-varid'>liftM</span> <span class='hs-varid'>return</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varop'>$</span> <span class='hs-varid'>liftM</span> <span class='hs-conid'>StExc</span> <span class='hs-varop'>.</span> <span class='hs-varid'>runExceptionT</span>
<a name="line-491"></a> <span class='hs-varid'>restoreT</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>liftM</span> <span class='hs-varid'>unStExc</span>
<a name="line-492"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-varid'>b</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-varid'>b</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-493"></a> <span class='hs-keyword'>newtype</span> <span class='hs-conid'>StM</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>StE</span> <span class='hs-layout'>{</span> <span class='hs-varid'>unStE</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ComposeSt</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span> <span class='hs-layout'>}</span>
<a name="line-494"></a> <span class='hs-varid'>liftBaseWith</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>defaultLiftBaseWith</span> <span class='hs-conid'>StE</span>
<a name="line-495"></a> <span class='hs-varid'>restoreM</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>defaultRestoreM</span> <span class='hs-varid'>unStE</span>
<a name="line-496"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span><span class='hs-layout'>,</span> <span class='hs-conid'>MonadBaseControl</span> <span class='hs-layout'>(</span><span class='hs-conid'>Base</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span>
<a name="line-497"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceThrow</span> <span class='hs-layout'>(</span><span class='hs-conid'>ExceptionT</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-498"></a> <span class='hs-varid'>resourceThrow</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ExceptionT</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span> <span class='hs-varop'>.</span> <span class='hs-conid'>Left</span> <span class='hs-varop'>.</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>toException</span>
<a name="line-499"></a>
<a name="line-500"></a><a name="ResourceThrow"></a><span class='hs-comment'>-- | A 'Resource' which can throw exceptions. Note that this does not work in a</span>
<a name="line-501"></a><a name="ResourceThrow"></a><span class='hs-comment'>-- vanilla @ST@ monad. Instead, you should use the 'ExceptionT' transformer on</span>
<a name="line-502"></a><a name="ResourceThrow"></a><span class='hs-comment'>-- top of @ST@.</span>
<a name="line-503"></a><a name="ResourceThrow"></a><span class='hs-keyword'>class</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceThrow</span> <span class='hs-varid'>m</span> <span class='hs-keyword'>where</span>
<a name="line-504"></a> <span class='hs-varid'>resourceThrow</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'>e</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>m</span> <span class='hs-varid'>a</span>
<a name="line-505"></a>
<a name="line-506"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>ResourceThrow</span> <span class='hs-conid'>IO</span> <span class='hs-keyword'>where</span>
<a name="line-507"></a> <span class='hs-varid'>resourceThrow</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>E</span><span class='hs-varop'>.</span><span class='hs-varid'>throwIO</span>
<a name="line-508"></a>
<a name="line-509"></a><span class='hs-cpp'>#define GO(T) instance (ResourceThrow m) => ResourceThrow (T m) where resourceThrow = lift . resourceThrow</span>
<a name="line-510"></a><span class='hs-cpp'>#define GOX(X, T) instance (X, ResourceThrow m) => ResourceThrow (T m) where resourceThrow = lift . resourceThrow</span>
<a name="line-511"></a><span class='hs-conid'>GO</span><span class='hs-layout'>(</span><span class='hs-conid'>IdentityT</span><span class='hs-layout'>)</span>
<a name="line-512"></a><span class='hs-conid'>GO</span><span class='hs-layout'>(</span><span class='hs-conid'>ListT</span><span class='hs-layout'>)</span>
<a name="line-513"></a><span class='hs-conid'>GO</span><span class='hs-layout'>(</span><span class='hs-conid'>MaybeT</span><span class='hs-layout'>)</span>
<a name="line-514"></a><span class='hs-conid'>GOX</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-conid'>ErrorT</span> <span class='hs-varid'>e</span><span class='hs-layout'>)</span>
<a name="line-515"></a><span class='hs-conid'>GO</span><span class='hs-layout'>(</span><span class='hs-conid'>ReaderT</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-516"></a><span class='hs-conid'>GO</span><span class='hs-layout'>(</span><span class='hs-conid'>StateT</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span>
<a name="line-517"></a><span class='hs-conid'>GOX</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'>WriterT</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-518"></a><span class='hs-conid'>GOX</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'>RWST</span> <span class='hs-varid'>r</span> <span class='hs-varid'>w</span> <span class='hs-varid'>s</span><span class='hs-layout'>)</span>
<a name="line-519"></a><span class='hs-conid'>GOX</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'>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-layout'>)</span>
<a name="line-520"></a><span class='hs-conid'>GO</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-layout'>)</span>
<a name="line-521"></a><span class='hs-conid'>GOX</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'>Strict</span><span class='hs-varop'>.</span><span class='hs-conid'>WriterT</span> <span class='hs-varid'>w</span><span class='hs-layout'>)</span>
<a name="line-522"></a><span class='hs-cpp'>#undef GO</span>
<a name="line-523"></a><span class='hs-cpp'>#undef GOX</span>
<a name="line-524"></a>
<a name="line-525"></a><a name="resourceForkIO"></a><span class='hs-comment'>-- | Introduce a reference-counting scheme to allow a resource context to be</span>
<a name="line-526"></a><span class='hs-comment'>-- shared by multiple threads. Once the last thread exits, all remaining</span>
<a name="line-527"></a><span class='hs-comment'>-- resources will be released.</span>
<a name="line-528"></a><span class='hs-comment'>--</span>
<a name="line-529"></a><span class='hs-comment'>-- Note that abuse of this function will greatly delay the deallocation of</span>
<a name="line-530"></a><span class='hs-comment'>-- registered resources. This function should be used with care. A general</span>
<a name="line-531"></a><span class='hs-comment'>-- guideline:</span>
<a name="line-532"></a><span class='hs-comment'>--</span>
<a name="line-533"></a><span class='hs-comment'>-- If you are allocating a resource that should be shared by multiple threads,</span>
<a name="line-534"></a><span class='hs-comment'>-- and will be held for a long time, you should allocate it at the beginning of</span>
<a name="line-535"></a><span class='hs-comment'>-- a new @ResourceT@ block and then call @resourceForkIO@ from there.</span>
<a name="line-536"></a><span class='hs-definition'>resourceForkIO</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>ResourceIO</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-conid'>()</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-conid'>ThreadId</span>
<a name="line-537"></a><span class='hs-definition'>resourceForkIO</span> <span class='hs-layout'>(</span><span class='hs-conid'>ResourceT</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>L</span><span class='hs-varop'>.</span><span class='hs-varid'>mask</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>restore</span> <span class='hs-keyglyph'>-></span>
<a name="line-538"></a> <span class='hs-comment'>-- We need to make sure the counter is incremented before this call</span>
<a name="line-539"></a> <span class='hs-comment'>-- returns. Otherwise, the parent thread may call runResourceT before</span>
<a name="line-540"></a> <span class='hs-comment'>-- the child thread increments, and all resources will be freed</span>
<a name="line-541"></a> <span class='hs-comment'>-- before the child gets called.</span>
<a name="line-542"></a> <span class='hs-varid'>resourceBracket_</span>
<a name="line-543"></a> <span class='hs-layout'>(</span><span class='hs-varid'>stateAlloc</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-544"></a> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-545"></a> <span class='hs-layout'>(</span><span class='hs-varid'>liftBaseDiscard</span> <span class='hs-varid'>forkIO</span> <span class='hs-varop'>$</span> <span class='hs-varid'>resourceBracket_</span>
<a name="line-546"></a> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-547"></a> <span class='hs-layout'>(</span><span class='hs-varid'>stateCleanup</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-548"></a> <span class='hs-layout'>(</span><span class='hs-varid'>restore</span> <span class='hs-varop'>$</span> <span class='hs-varid'>f</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-549"></a>
<a name="line-550"></a><a name="resourceActive"></a><span class='hs-comment'>-- | Determine if the current @ResourceT@ is still active. This is necessary</span>
<a name="line-551"></a><span class='hs-comment'>-- for such cases as lazy I\/O, where an unevaluated thunk may still refer to a</span>
<a name="line-552"></a><span class='hs-comment'>-- closed @ResourceT@.</span>
<a name="line-553"></a><span class='hs-definition'>resourceActive</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Resource</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>ResourceT</span> <span class='hs-varid'>m</span> <span class='hs-conid'>Bool</span>
<a name="line-554"></a><span class='hs-definition'>resourceActive</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>ResourceT</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>rmMap</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-555"></a> <span class='hs-varid'>rm</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>resourceLiftBase</span> <span class='hs-varop'>$</span> <span class='hs-varid'>readRef'</span> <span class='hs-varid'>rmMap</span>
<a name="line-556"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>rm</span> <span class='hs-keyword'>of</span>
<a name="line-557"></a> <span class='hs-conid'>ReleaseMapClosed</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>False</span>
<a name="line-558"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>True</span>
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