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<pre><a name="line-1"></a><span class='hs-comment'>-- |</span>
<a name="line-2"></a><span class='hs-comment'>-- Module: Data.Enumerator.Internal</span>
<a name="line-3"></a><span class='hs-comment'>-- Copyright: 2010-2011 John Millikin</span>
<a name="line-4"></a><span class='hs-comment'>-- License: MIT</span>
<a name="line-5"></a><span class='hs-comment'>--</span>
<a name="line-6"></a><span class='hs-comment'>-- Maintainer: jmillikin@gmail.com</span>
<a name="line-7"></a><span class='hs-comment'>-- Portability: portable</span>
<a name="line-8"></a><span class='hs-comment'>--</span>
<a name="line-9"></a><span class='hs-comment'>-- Core enumerator types, and some useful primitives.</span>
<a name="line-10"></a><span class='hs-comment'>--</span>
<a name="line-11"></a><span class='hs-comment'>-- Be careful when using the functions defined in this module, as they will</span>
<a name="line-12"></a><span class='hs-comment'>-- allow you to create iteratees which violate the monad laws.</span>
<a name="line-13"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Enumerator</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span>
<a name="line-14"></a> <span class='hs-layout'>(</span> <span class='hs-conid'>Stream</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-15"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Iteratee</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-16"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Step</span> <span class='hs-layout'>(</span><span class='hs-keyglyph'>..</span><span class='hs-layout'>)</span>
<a name="line-17"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Enumerator</span>
<a name="line-18"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Enumeratee</span>
<a name="line-19"></a>
<a name="line-20"></a> <span class='hs-comment'>-- * Primitives</span>
<a name="line-21"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>returnI</span>
<a name="line-22"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>continue</span>
<a name="line-23"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>yield</span>
<a name="line-24"></a>
<a name="line-25"></a> <span class='hs-comment'>-- * Operators</span>
<a name="line-26"></a> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>>>==</span><span class='hs-layout'>)</span>
<a name="line-27"></a> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>==<<</span><span class='hs-layout'>)</span>
<a name="line-28"></a> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>$$</span><span class='hs-layout'>)</span>
<a name="line-29"></a> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'>>==></span><span class='hs-layout'>)</span>
<a name="line-30"></a> <span class='hs-layout'>,</span> <span class='hs-layout'>(</span><span class='hs-varop'><==<</span><span class='hs-layout'>)</span>
<a name="line-31"></a>
<a name="line-32"></a> <span class='hs-comment'>-- * Miscellaneous</span>
<a name="line-33"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>enumEOF</span>
<a name="line-34"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>checkContinue0</span>
<a name="line-35"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>checkContinue1</span>
<a name="line-36"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>checkDoneEx</span>
<a name="line-37"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>checkDone</span>
<a name="line-38"></a>
<a name="line-39"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-40"></a>
<a name="line-41"></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-keyword'>as</span> <span class='hs-conid'>A</span>
<a name="line-42"></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'>Exc</span>
<a name="line-43"></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-keyword'>as</span> <span class='hs-conid'>CM</span>
<a name="line-44"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Class</span> <span class='hs-layout'>(</span><span class='hs-conid'>MonadIO</span><span class='hs-layout'>,</span> <span class='hs-varid'>liftIO</span><span class='hs-layout'>)</span>
<a name="line-45"></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-varid'>lift</span><span class='hs-layout'>)</span>
<a name="line-46"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Function</span> <span class='hs-layout'>(</span><span class='hs-varid'>fix</span><span class='hs-layout'>)</span>
<a name="line-47"></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> <span class='hs-varid'>mempty</span><span class='hs-layout'>,</span> <span class='hs-varid'>mappend</span><span class='hs-layout'>,</span> <span class='hs-varid'>mconcat</span><span class='hs-layout'>)</span>
<a name="line-48"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>Typeable</span> <span class='hs-layout'>(</span> <span class='hs-conid'>Typeable</span><span class='hs-layout'>,</span> <span class='hs-varid'>typeOf</span>
<a name="line-49"></a> <span class='hs-layout'>,</span> <span class='hs-conid'>Typeable1</span><span class='hs-layout'>,</span> <span class='hs-varid'>typeOf1</span>
<a name="line-50"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>mkTyConApp</span><span class='hs-layout'>,</span> <span class='hs-varid'>mkTyCon</span><span class='hs-layout'>)</span>
<a name="line-51"></a>
<a name="line-52"></a><a name="Stream"></a><span class='hs-comment'>-- | A 'Stream' is a sequence of chunks generated by an 'Enumerator'.</span>
<a name="line-53"></a><a name="Stream"></a><span class='hs-comment'>--</span>
<a name="line-54"></a><a name="Stream"></a><span class='hs-comment'>-- @('Chunks' [])@ is used to indicate that a stream is still active, but</span>
<a name="line-55"></a><a name="Stream"></a><span class='hs-comment'>-- currently has no available data. Iteratees should ignore empty chunks.</span>
<a name="line-56"></a><a name="Stream"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span>
<a name="line-57"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Chunks</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-58"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>EOF</span>
<a name="line-59"></a> <span class='hs-keyword'>deriving</span> <span class='hs-layout'>(</span><span class='hs-conid'>Show</span><span class='hs-layout'>,</span> <span class='hs-conid'>Eq</span><span class='hs-layout'>)</span>
<a name="line-60"></a>
<a name="line-61"></a><a name="instance%20Monad%20Stream"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monad</span> <span class='hs-conid'>Stream</span> <span class='hs-keyword'>where</span>
<a name="line-62"></a> <span class='hs-varid'>return</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Chunks</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span>
<a name="line-63"></a> <span class='hs-conid'>Chunks</span> <span class='hs-varid'>xs</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mconcat</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span>
<a name="line-64"></a> <span class='hs-conid'>EOF</span> <span class='hs-varop'>>>=</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>EOF</span>
<a name="line-65"></a>
<a name="line-66"></a><a name="instance%20Monoid%20(Stream%20a)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Monoid</span> <span class='hs-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-67"></a> <span class='hs-varid'>mempty</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Chunks</span> <span class='hs-varid'>mempty</span>
<a name="line-68"></a> <span class='hs-varid'>mappend</span> <span class='hs-layout'>(</span><span class='hs-conid'>Chunks</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-conid'>Chunks</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Chunks</span> <span class='hs-layout'>(</span><span class='hs-varid'>xs</span> <span class='hs-varop'>++</span> <span class='hs-varid'>ys</span><span class='hs-layout'>)</span>
<a name="line-69"></a> <span class='hs-varid'>mappend</span> <span class='hs-keyword'>_</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>EOF</span>
<a name="line-70"></a>
<a name="line-71"></a><a name="Step"></a><span class='hs-keyword'>data</span> <span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-72"></a> <span class='hs-comment'>-- | The 'Iteratee' is capable of accepting more input. Note that more input</span>
<a name="line-73"></a> <span class='hs-comment'>-- is not necessarily required; the 'Iteratee' might be able to generate a</span>
<a name="line-74"></a> <span class='hs-comment'>-- value immediately if it receives 'EOF'.</span>
<a name="line-75"></a> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Continue</span> <span class='hs-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-76"></a>
<a name="line-77"></a> <span class='hs-comment'>-- | The 'Iteratee' cannot receive any more input, and has generated a</span>
<a name="line-78"></a> <span class='hs-comment'>-- result. Included in this value is left-over input, which can be passed to</span>
<a name="line-79"></a> <span class='hs-comment'>-- composed 'Iteratee's.</span>
<a name="line-80"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Yield</span> <span class='hs-varid'>b</span> <span class='hs-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-81"></a>
<a name="line-82"></a> <span class='hs-comment'>-- | The 'Iteratee' encountered an error which prevents it from proceeding</span>
<a name="line-83"></a> <span class='hs-comment'>-- further.</span>
<a name="line-84"></a> <span class='hs-keyglyph'>|</span> <span class='hs-conid'>Error</span> <span class='hs-conid'>Exc</span><span class='hs-varop'>.</span><span class='hs-conid'>SomeException</span>
<a name="line-85"></a>
<a name="line-86"></a><span class='hs-comment'>-- | The primary data type for this library; an iteratee consumes</span>
<a name="line-87"></a><span class='hs-comment'>-- chunks of input from a stream until it either yields a value or</span>
<a name="line-88"></a><span class='hs-comment'>-- encounters an error.</span>
<a name="line-89"></a><span class='hs-comment'>--</span>
<a name="line-90"></a><span class='hs-comment'>-- Compatibility note: @Iteratee@ will become abstract in @enumerator_0.5@. If</span>
<a name="line-91"></a><span class='hs-comment'>-- you depend on internal implementation details, please import</span>
<a name="line-92"></a><span class='hs-comment'>-- @"Data.Enumerator.Internal"@.</span>
<a name="line-93"></a>
<a name="line-94"></a><a name="Iteratee"></a><span class='hs-comment'>-- In general, iteratees begin in the 'Continue' state. As each chunk is</span>
<a name="line-95"></a><a name="Iteratee"></a><span class='hs-comment'>-- passed to the continuation, the iteratee returns the next step:</span>
<a name="line-96"></a><a name="Iteratee"></a><span class='hs-comment'>-- 'Continue' for more data, 'Yield' when it's finished, or 'Error' to</span>
<a name="line-97"></a><a name="Iteratee"></a><span class='hs-comment'>-- abort processing.</span>
<a name="line-98"></a><a name="Iteratee"></a><span class='hs-keyword'>newtype</span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Iteratee</span>
<a name="line-99"></a> <span class='hs-layout'>{</span> <span class='hs-varid'>runIteratee</span> <span class='hs-keyglyph'>::</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-100"></a> <span class='hs-layout'>}</span>
<a name="line-101"></a>
<a name="line-102"></a><a name="instance%20Monad%20(Iteratee%20a%20m)"></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'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-103"></a> <span class='hs-varid'>return</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>yield</span> <span class='hs-varid'>x</span> <span class='hs-layout'>(</span><span class='hs-conid'>Chunks</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span>
<a name="line-104"></a>
<a name="line-105"></a> <span class='hs-varid'>m0</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varop'>$</span> <span class='hs-varid'>m0</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-varid'>fix</span> <span class='hs-varop'>$</span>
<a name="line-106"></a> <span class='hs-keyglyph'>\</span><span class='hs-varid'>bind</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varop'>$</span> <span class='hs-varid'>runIteratee</span> <span class='hs-varid'>m</span> <span class='hs-varop'>>>=</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r1</span> <span class='hs-keyglyph'>-></span>
<a name="line-107"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>r1</span> <span class='hs-keyword'>of</span>
<a name="line-108"></a> <span class='hs-conid'>Continue</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Continue</span> <span class='hs-layout'>(</span><span class='hs-varid'>bind</span> <span class='hs-varop'>.</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-109"></a> <span class='hs-conid'>Error</span> <span class='hs-varid'>err</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Error</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span>
<a name="line-110"></a> <span class='hs-conid'>Yield</span> <span class='hs-varid'>x</span> <span class='hs-layout'>(</span><span class='hs-conid'>Chunks</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runIteratee</span> <span class='hs-layout'>(</span><span class='hs-varid'>f</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-111"></a> <span class='hs-conid'>Yield</span> <span class='hs-varid'>x</span> <span class='hs-varid'>extra</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runIteratee</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-varop'>>>=</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>r2</span> <span class='hs-keyglyph'>-></span>
<a name="line-112"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>r2</span> <span class='hs-keyword'>of</span>
<a name="line-113"></a> <span class='hs-conid'>Continue</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>runIteratee</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span> <span class='hs-varid'>extra</span><span class='hs-layout'>)</span>
<a name="line-114"></a> <span class='hs-conid'>Error</span> <span class='hs-varid'>err</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Error</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span>
<a name="line-115"></a> <span class='hs-conid'>Yield</span> <span class='hs-varid'>x'</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Yield</span> <span class='hs-varid'>x'</span> <span class='hs-varid'>extra</span><span class='hs-layout'>)</span>
<a name="line-116"></a>
<a name="line-117"></a><a name="instance%20MonadTrans%20(Iteratee%20a)"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>MonadTrans</span> <span class='hs-layout'>(</span><span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-118"></a> <span class='hs-varid'>lift</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Iteratee</span> <span class='hs-layout'>(</span><span class='hs-varid'>m</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>runIteratee</span> <span class='hs-varop'>.</span> <span class='hs-varid'>return</span><span class='hs-layout'>)</span>
<a name="line-119"></a>
<a name="line-120"></a><a name="instance%20MonadIO%20(Iteratee%20a%20m)"></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'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-121"></a> <span class='hs-varid'>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-122"></a>
<a name="line-123"></a><span class='hs-comment'>-- | Enumerators are sources of data, to be consumed by iteratees.</span>
<a name="line-124"></a><span class='hs-comment'>-- Enumerators typically read from an external source (parser, handle,</span>
<a name="line-125"></a><span class='hs-comment'>-- random generator, etc), then feed chunks into an tteratee until:</span>
<a name="line-126"></a><span class='hs-comment'>--</span>
<a name="line-127"></a><span class='hs-comment'>-- * The input source runs out of data.</span>
<a name="line-128"></a><span class='hs-comment'>--</span>
<a name="line-129"></a><span class='hs-comment'>-- * The iteratee yields a result value.</span>
<a name="line-130"></a><span class='hs-comment'>--</span>
<a name="line-131"></a><span class='hs-comment'>-- * The iteratee throws an exception.</span>
<a name="line-132"></a>
<a name="line-133"></a><a name="Enumerator"></a><span class='hs-comment'>-- Since @'Iteratee'@ is an alias for @m ('Step' a m b)@, 'Enumerator's can</span>
<a name="line-134"></a><a name="Enumerator"></a><span class='hs-comment'>-- be considered step transformers of type @'Step' a m b -> m ('Step' a m b)@.</span>
<a name="line-135"></a><a name="Enumerator"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-136"></a>
<a name="line-137"></a><a name="Enumeratee"></a><span class='hs-comment'>-- | An enumeratee acts as a stream adapter; place one between an enumerator</span>
<a name="line-138"></a><a name="Enumeratee"></a><span class='hs-comment'>-- and an iteratee, and it changes the type or contents of the input stream.</span>
<a name="line-139"></a><a name="Enumeratee"></a><span class='hs-comment'>--</span>
<a name="line-140"></a><a name="Enumeratee"></a><span class='hs-comment'>-- Most users will want to combine enumerators, enumeratees, and iteratees</span>
<a name="line-141"></a><a name="Enumeratee"></a><span class='hs-comment'>-- using the stream combinators @joinI@ and @joinE@, or their operator aliases</span>
<a name="line-142"></a><a name="Enumeratee"></a><span class='hs-comment'>-- @(=$)@ and @($=)@. These combinators are used to manage how left-over input</span>
<a name="line-143"></a><a name="Enumeratee"></a><span class='hs-comment'>-- is passed between elements of the data processing pipeline.</span>
<a name="line-144"></a><a name="Enumeratee"></a><span class='hs-keyword'>type</span> <span class='hs-conid'>Enumeratee</span> <span class='hs-varid'>ao</span> <span class='hs-varid'>ai</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Step</span> <span class='hs-varid'>ai</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>ao</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>ai</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-145"></a>
<a name="line-146"></a><a name="instance%20Typeable1%20Stream"></a><span class='hs-comment'>-- | Since: 0.4.8</span>
<a name="line-147"></a><a name="instance%20Typeable1%20Stream"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Typeable1</span> <span class='hs-conid'>Stream</span> <span class='hs-keyword'>where</span>
<a name="line-148"></a> <span class='hs-varid'>typeOf1</span> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTyConApp</span> <span class='hs-varid'>tyCon</span> <span class='hs-conid'>[]</span> <span class='hs-keyword'>where</span>
<a name="line-149"></a> <span class='hs-varid'>tyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTyCon</span> <span class='hs-str'>"Data.Enumerator.Stream"</span>
<a name="line-150"></a>
<a name="line-151"></a><a name="instance%20Typeable1%20(Iteratee%20a%20m)"></a><span class='hs-comment'>-- | Since: 0.4.6</span>
<a name="line-152"></a><a name="instance%20Typeable1%20(Iteratee%20a%20m)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Typeable</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Typeable1</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span>
<a name="line-153"></a> <span class='hs-conid'>Typeable1</span> <span class='hs-layout'>(</span><span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-154"></a> <span class='hs-varid'>typeOf1</span> <span class='hs-varid'>i</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span>
<a name="line-155"></a> <span class='hs-varid'>tyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTyCon</span> <span class='hs-str'>"Data.Enumerator.Iteratee"</span>
<a name="line-156"></a> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>peel</span> <span class='hs-varid'>i</span>
<a name="line-157"></a>
<a name="line-158"></a> <span class='hs-varid'>peel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</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'>m</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-159"></a> <span class='hs-varid'>peel</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>undefined</span>
<a name="line-160"></a>
<a name="line-161"></a> <span class='hs-keyword'>in</span> <span class='hs-varid'>mkTyConApp</span> <span class='hs-varid'>tyCon</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>typeOf</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>typeOf1</span> <span class='hs-varid'>m</span><span class='hs-keyglyph'>]</span>
<a name="line-162"></a>
<a name="line-163"></a><a name="instance%20Typeable1%20(Step%20a%20m)"></a><span class='hs-comment'>-- | Since: 0.4.8</span>
<a name="line-164"></a><a name="instance%20Typeable1%20(Step%20a%20m)"></a><span class='hs-keyword'>instance</span> <span class='hs-layout'>(</span><span class='hs-conid'>Typeable</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-conid'>Typeable1</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=></span>
<a name="line-165"></a> <span class='hs-conid'>Typeable1</span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-166"></a> <span class='hs-varid'>typeOf1</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span>
<a name="line-167"></a> <span class='hs-varid'>tyCon</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mkTyCon</span> <span class='hs-str'>"Data.Enumerator.Step"</span>
<a name="line-168"></a> <span class='hs-layout'>(</span><span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>peel</span> <span class='hs-varid'>s</span>
<a name="line-169"></a>
<a name="line-170"></a> <span class='hs-varid'>peel</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</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'>m</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span>
<a name="line-171"></a> <span class='hs-varid'>peel</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>undefined</span>
<a name="line-172"></a>
<a name="line-173"></a> <span class='hs-keyword'>in</span> <span class='hs-varid'>mkTyConApp</span> <span class='hs-varid'>tyCon</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>typeOf</span> <span class='hs-varid'>a</span><span class='hs-layout'>,</span> <span class='hs-varid'>typeOf1</span> <span class='hs-varid'>m</span><span class='hs-keyglyph'>]</span>
<a name="line-174"></a>
<a name="line-175"></a><a name="instance%20Functor%20(Iteratee%20a%20m)"></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'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-176"></a> <span class='hs-varid'>fmap</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>CM</span><span class='hs-varop'>.</span><span class='hs-varid'>liftM</span>
<a name="line-177"></a>
<a name="line-178"></a><a name="instance%20A.Applicative%20(Iteratee%20a%20m)"></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'>A</span><span class='hs-varop'>.</span><span class='hs-conid'>Applicative</span> <span class='hs-layout'>(</span><span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-179"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span>
<a name="line-180"></a> <span class='hs-layout'>(</span><span class='hs-varop'><*></span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>CM</span><span class='hs-varop'>.</span><span class='hs-varid'>ap</span>
<a name="line-181"></a>
<a name="line-182"></a><a name="instance%20Functor%20Stream"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>Functor</span> <span class='hs-conid'>Stream</span> <span class='hs-keyword'>where</span>
<a name="line-183"></a> <span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Chunks</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Chunks</span> <span class='hs-layout'>(</span><span class='hs-varid'>fmap</span> <span class='hs-varid'>f</span> <span class='hs-varid'>xs</span><span class='hs-layout'>)</span>
<a name="line-184"></a> <span class='hs-varid'>fmap</span> <span class='hs-keyword'>_</span> <span class='hs-conid'>EOF</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>EOF</span>
<a name="line-185"></a>
<a name="line-186"></a><a name="instance%20A.Applicative%20Stream"></a><span class='hs-comment'>-- | Since: 0.4.5</span>
<a name="line-187"></a><a name="instance%20A.Applicative%20Stream"></a><span class='hs-keyword'>instance</span> <span class='hs-conid'>A</span><span class='hs-varop'>.</span><span class='hs-conid'>Applicative</span> <span class='hs-conid'>Stream</span> <span class='hs-keyword'>where</span>
<a name="line-188"></a> <span class='hs-varid'>pure</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>return</span>
<a name="line-189"></a> <span class='hs-layout'>(</span><span class='hs-varop'><*></span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>CM</span><span class='hs-varop'>.</span><span class='hs-varid'>ap</span>
<a name="line-190"></a>
<a name="line-191"></a><a name="returnI"></a><span class='hs-comment'>-- | @'returnI' step = 'Iteratee' (return step)@</span>
<a name="line-192"></a><span class='hs-definition'>returnI</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'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-193"></a><span class='hs-definition'>returnI</span> <span class='hs-varid'>step</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Iteratee</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varid'>step</span><span class='hs-layout'>)</span>
<a name="line-194"></a>
<a name="line-195"></a><a name="yield"></a><span class='hs-comment'>-- | @'yield' x extra = 'returnI' ('Yield' x extra)@</span>
<a name="line-196"></a><span class='hs-comment'>--</span>
<a name="line-197"></a><span class='hs-comment'>-- WARNING: due to the current encoding of iteratees in this library,</span>
<a name="line-198"></a><span class='hs-comment'>-- careless use of the 'yield' primitive may violate the monad laws.</span>
<a name="line-199"></a><span class='hs-comment'>-- To prevent this, always make sure that an iteratee never yields</span>
<a name="line-200"></a><span class='hs-comment'>-- extra data unless it has received at least one input element.</span>
<a name="line-201"></a><span class='hs-comment'>--</span>
<a name="line-202"></a><span class='hs-comment'>-- More strictly, iteratees may not yield data that they did not</span>
<a name="line-203"></a><span class='hs-comment'>-- receive as input. Don't use 'yield' to &#x201c;inject&#x201d; elements</span>
<a name="line-204"></a><span class='hs-comment'>-- into the stream.</span>
<a name="line-205"></a><span class='hs-definition'>yield</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-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-206"></a><span class='hs-definition'>yield</span> <span class='hs-varid'>x</span> <span class='hs-varid'>extra</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>returnI</span> <span class='hs-layout'>(</span><span class='hs-conid'>Yield</span> <span class='hs-varid'>x</span> <span class='hs-varid'>extra</span><span class='hs-layout'>)</span>
<a name="line-207"></a>
<a name="line-208"></a><a name="continue"></a><span class='hs-comment'>-- | @'continue' k = 'returnI' ('Continue' k)@</span>
<a name="line-209"></a><span class='hs-definition'>continue</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-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</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-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-210"></a><span class='hs-definition'>continue</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>returnI</span> <span class='hs-layout'>(</span><span class='hs-conid'>Continue</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span>
<a name="line-211"></a>
<a name="line-212"></a><span class='hs-keyword'>infixl</span> <span class='hs-num'>1</span> <span class='hs-varop'>>>==</span>
<a name="line-213"></a><span class='hs-keyword'>infixr</span> <span class='hs-num'>1</span> <span class='hs-varop'>==<<</span>
<a name="line-214"></a><span class='hs-keyword'>infixr</span> <span class='hs-num'>0</span> <span class='hs-varop'>$$</span>
<a name="line-215"></a><span class='hs-keyword'>infixr</span> <span class='hs-num'>1</span> <span class='hs-varop'>>==></span>
<a name="line-216"></a><span class='hs-keyword'>infixr</span> <span class='hs-num'>1</span> <span class='hs-varop'><==<</span>
<a name="line-217"></a>
<a name="line-218"></a><a name="%3e%3e=="></a><span class='hs-comment'>-- | The most primitive stream operator. @iter >>== enum@ returns a new</span>
<a name="line-219"></a><span class='hs-comment'>-- iteratee which will read from @enum@ before continuing.</span>
<a name="line-220"></a><span class='hs-layout'>(</span><span class='hs-varop'>>>==</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-221"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-222"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span><span class='hs-layout'>)</span>
<a name="line-223"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span>
<a name="line-224"></a><a name="i"></a><span class='hs-definition'>i</span> <span class='hs-varop'>>>==</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Iteratee</span> <span class='hs-layout'>(</span><span class='hs-varid'>runIteratee</span> <span class='hs-varid'>i</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>runIteratee</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span><span class='hs-layout'>)</span>
<a name="line-225"></a>
<a name="line-226"></a><a name="==%3c%3c"></a><span class='hs-comment'>-- | @('==<<') = flip ('>>==')@</span>
<a name="line-227"></a><span class='hs-layout'>(</span><span class='hs-varop'>==<<</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-228"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span><span class='hs-layout'>)</span>
<a name="line-229"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-230"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span>
<a name="line-231"></a><span class='hs-layout'>(</span><span class='hs-varop'>==<<</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>flip</span> <span class='hs-layout'>(</span><span class='hs-varop'>>>==</span><span class='hs-layout'>)</span>
<a name="line-232"></a>
<a name="line-233"></a><a name="$$"></a><span class='hs-comment'>-- | @('$$') = ('==<<')@</span>
<a name="line-234"></a><span class='hs-comment'>--</span>
<a name="line-235"></a><span class='hs-comment'>-- This is somewhat easier to read when constructing an iteratee from many</span>
<a name="line-236"></a><span class='hs-comment'>-- processing stages. You can treat it like @('$')@, and read the data flow</span>
<a name="line-237"></a><span class='hs-comment'>-- from left to right.</span>
<a name="line-238"></a><span class='hs-comment'>--</span>
<a name="line-239"></a><span class='hs-comment'>-- Since: 0.1.1</span>
<a name="line-240"></a><span class='hs-layout'>(</span><span class='hs-varop'>$$</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-241"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span><span class='hs-layout'>)</span>
<a name="line-242"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-243"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span>
<a name="line-244"></a><span class='hs-layout'>(</span><span class='hs-varop'>$$</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-layout'>(</span><span class='hs-varop'>==<<</span><span class='hs-layout'>)</span>
<a name="line-245"></a>
<a name="line-246"></a><a name="%3e==%3e"></a><span class='hs-comment'>-- | @('>==>') enum1 enum2 step = enum1 step '>>==' enum2@</span>
<a name="line-247"></a><span class='hs-comment'>--</span>
<a name="line-248"></a><span class='hs-comment'>-- The moral equivalent of @('CM.>=>')@ for iteratees.</span>
<a name="line-249"></a><span class='hs-comment'>--</span>
<a name="line-250"></a><span class='hs-comment'>-- Since: 0.1.1</span>
<a name="line-251"></a><span class='hs-layout'>(</span><span class='hs-varop'>>==></span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-252"></a> <span class='hs-keyglyph'>=></span> <span class='hs-conid'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-253"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span><span class='hs-layout'>)</span>
<a name="line-254"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-255"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span>
<a name="line-256"></a><span class='hs-layout'>(</span><span class='hs-varop'>>==></span><span class='hs-layout'>)</span> <span class='hs-varid'>e1</span> <span class='hs-varid'>e2</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>e1</span> <span class='hs-varid'>s</span> <span class='hs-varop'>>>==</span> <span class='hs-varid'>e2</span>
<a name="line-257"></a>
<a name="line-258"></a><a name="%3c==%3c"></a><span class='hs-comment'>-- | @('<==<') = flip ('>==>')@</span>
<a name="line-259"></a><span class='hs-comment'>--</span>
<a name="line-260"></a><span class='hs-comment'>-- Since: 0.1.1</span>
<a name="line-261"></a><span class='hs-layout'>(</span><span class='hs-varop'><==<</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-262"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span><span class='hs-layout'>)</span>
<a name="line-263"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-264"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-265"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b'</span>
<a name="line-266"></a><span class='hs-layout'>(</span><span class='hs-varop'><==<</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>flip</span> <span class='hs-layout'>(</span><span class='hs-varop'>>==></span><span class='hs-layout'>)</span>
<a name="line-267"></a>
<a name="line-268"></a><a name="enumEOF"></a><span class='hs-comment'>-- | Sends 'EOF' to its iteratee. Most clients should use 'run' or 'run_'</span>
<a name="line-269"></a><span class='hs-comment'>-- instead.</span>
<a name="line-270"></a><span class='hs-definition'>enumEOF</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'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-271"></a><span class='hs-definition'>enumEOF</span> <span class='hs-layout'>(</span><span class='hs-conid'>Yield</span> <span class='hs-varid'>x</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>yield</span> <span class='hs-varid'>x</span> <span class='hs-conid'>EOF</span>
<a name="line-272"></a><span class='hs-definition'>enumEOF</span> <span class='hs-layout'>(</span><span class='hs-conid'>Error</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>returnI</span> <span class='hs-layout'>(</span><span class='hs-conid'>Error</span> <span class='hs-varid'>err</span><span class='hs-layout'>)</span>
<a name="line-273"></a><span class='hs-definition'>enumEOF</span> <span class='hs-layout'>(</span><span class='hs-conid'>Continue</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>k</span> <span class='hs-conid'>EOF</span> <span class='hs-varop'>>>==</span> <span class='hs-varid'>check</span> <span class='hs-keyword'>where</span>
<a name="line-274"></a> <span class='hs-varid'>check</span> <span class='hs-layout'>(</span><span class='hs-conid'>Continue</span> <span class='hs-keyword'>_</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>error</span> <span class='hs-str'>"enumEOF: divergent iteratee"</span>
<a name="line-275"></a> <span class='hs-varid'>check</span> <span class='hs-varid'>s</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>enumEOF</span> <span class='hs-varid'>s</span>
<a name="line-276"></a>
<a name="line-277"></a><a name="checkDoneEx"></a><span class='hs-comment'>-- | A common pattern in 'Enumeratee' implementations is to check whether</span>
<a name="line-278"></a><span class='hs-comment'>-- the inner 'Iteratee' has finished, and if so, to return its output.</span>
<a name="line-279"></a><span class='hs-comment'>-- 'checkDone' passes its parameter a continuation if the 'Iteratee'</span>
<a name="line-280"></a><span class='hs-comment'>-- can still consume input, or yields otherwise.</span>
<a name="line-281"></a><span class='hs-comment'>--</span>
<a name="line-282"></a><span class='hs-comment'>-- Since: 0.4.3</span>
<a name="line-283"></a><span class='hs-definition'>checkDoneEx</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span>
<a name="line-284"></a> <span class='hs-conid'>Stream</span> <span class='hs-varid'>a'</span> <span class='hs-keyglyph'>-></span>
<a name="line-285"></a> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</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-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span>
<a name="line-286"></a> <span class='hs-conid'>Enumeratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-287"></a><span class='hs-definition'>checkDoneEx</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>f</span> <span class='hs-layout'>(</span><span class='hs-conid'>Continue</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>f</span> <span class='hs-varid'>k</span>
<a name="line-288"></a><span class='hs-definition'>checkDoneEx</span> <span class='hs-varid'>extra</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>step</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>yield</span> <span class='hs-varid'>step</span> <span class='hs-varid'>extra</span>
<a name="line-289"></a>
<a name="line-290"></a><a name="checkDone"></a><span class='hs-comment'>-- | @'checkDone' = 'checkDoneEx' ('Chunks' [])@</span>
<a name="line-291"></a><span class='hs-comment'>--</span>
<a name="line-292"></a><span class='hs-comment'>-- Use this for enumeratees which do not have an input buffer.</span>
<a name="line-293"></a><span class='hs-definition'>checkDone</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span> <span class='hs-keyglyph'>=></span>
<a name="line-294"></a> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</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-conid'>Iteratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>m</span> <span class='hs-layout'>(</span><span class='hs-conid'>Step</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span>
<a name="line-295"></a> <span class='hs-conid'>Enumeratee</span> <span class='hs-varid'>a'</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-296"></a><span class='hs-definition'>checkDone</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>checkDoneEx</span> <span class='hs-layout'>(</span><span class='hs-conid'>Chunks</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span>
<a name="line-297"></a>
<a name="line-298"></a><a name="checkContinue0"></a><span class='hs-comment'>-- | A common pattern in 'Enumerator' implementations is to check whether</span>
<a name="line-299"></a><span class='hs-comment'>-- the inner 'Iteratee' has finished, and if so, to return its output.</span>
<a name="line-300"></a><span class='hs-comment'>-- 'checkContinue0' passes its parameter a continuation if the 'Iteratee'</span>
<a name="line-301"></a><span class='hs-comment'>-- can still consume input; if not, it returns the iteratee's step.</span>
<a name="line-302"></a><span class='hs-comment'>--</span>
<a name="line-303"></a><span class='hs-comment'>-- The type signature here is a bit crazy, but it's actually very easy to</span>
<a name="line-304"></a><span class='hs-comment'>-- use. Take this code:</span>
<a name="line-305"></a><span class='hs-comment'>--</span>
<a name="line-306"></a><span class='hs-comment'>-- > repeat :: Monad m => a -> Enumerator a m b</span>
<a name="line-307"></a><span class='hs-comment'>-- > repeat x = loop where</span>
<a name="line-308"></a><span class='hs-comment'>-- > loop (Continue k) = k (Chunks [x]) >>== loop</span>
<a name="line-309"></a><span class='hs-comment'>-- > loop step = returnI step</span>
<a name="line-310"></a><span class='hs-comment'>--</span>
<a name="line-311"></a><span class='hs-comment'>-- And rewrite it without the boilerplate:</span>
<a name="line-312"></a><span class='hs-comment'>--</span>
<a name="line-313"></a><span class='hs-comment'>-- > repeat :: Monad m => a -> Enumerator a m b</span>
<a name="line-314"></a><span class='hs-comment'>-- > repeat x = checkContinue0 $ \loop k -> k (Chunks [x] >>== loop</span>
<a name="line-315"></a><span class='hs-comment'>--</span>
<a name="line-316"></a><span class='hs-comment'>-- Since: 0.4.9</span>
<a name="line-317"></a><span class='hs-definition'>checkContinue0</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-318"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-conid'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-319"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-320"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-321"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-322"></a><span class='hs-definition'>checkContinue0</span> <span class='hs-varid'>inner</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>loop</span> <span class='hs-keyword'>where</span>
<a name="line-323"></a> <span class='hs-varid'>loop</span> <span class='hs-layout'>(</span><span class='hs-conid'>Continue</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>inner</span> <span class='hs-varid'>loop</span> <span class='hs-varid'>k</span>
<a name="line-324"></a> <span class='hs-varid'>loop</span> <span class='hs-varid'>step</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>returnI</span> <span class='hs-varid'>step</span>
<a name="line-325"></a>
<a name="line-326"></a>
<a name="line-327"></a><a name="checkContinue1"></a><span class='hs-comment'>-- | Like 'checkContinue0', but allows each loop step to use a state value:</span>
<a name="line-328"></a><span class='hs-comment'>--</span>
<a name="line-329"></a><span class='hs-comment'>-- > iterate :: Monad m => (a -> a) -> a -> Enumerator a m b</span>
<a name="line-330"></a><span class='hs-comment'>-- > iterate f = checkContinue1 $ \loop a k -> k (Chunks [a]) >>== loop (f a)</span>
<a name="line-331"></a><span class='hs-comment'>--</span>
<a name="line-332"></a><span class='hs-comment'>-- Since: 0.4.9</span>
<a name="line-333"></a><span class='hs-definition'>checkContinue1</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Monad</span> <span class='hs-varid'>m</span>
<a name="line-334"></a> <span class='hs-keyglyph'>=></span> <span class='hs-layout'>(</span><span class='hs-layout'>(</span><span class='hs-varid'>s1</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-335"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>s1</span>
<a name="line-336"></a> <span class='hs-keyglyph'>-></span> <span class='hs-layout'>(</span><span class='hs-conid'>Stream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-337"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Iteratee</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span>
<a name="line-338"></a> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>s1</span>
<a name="line-339"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>Enumerator</span> <span class='hs-varid'>a</span> <span class='hs-varid'>m</span> <span class='hs-varid'>b</span>
<a name="line-340"></a><span class='hs-definition'>checkContinue1</span> <span class='hs-varid'>inner</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>loop</span> <span class='hs-keyword'>where</span>
<a name="line-341"></a> <span class='hs-varid'>loop</span> <span class='hs-varid'>s</span> <span class='hs-layout'>(</span><span class='hs-conid'>Continue</span> <span class='hs-varid'>k</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>inner</span> <span class='hs-varid'>loop</span> <span class='hs-varid'>s</span> <span class='hs-varid'>k</span>
<a name="line-342"></a> <span class='hs-varid'>loop</span> <span class='hs-keyword'>_</span> <span class='hs-varid'>step</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>returnI</span> <span class='hs-varid'>step</span>
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