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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE BangPatterns #-}</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='hs-comment'>-- | List conversions and utilities.</span>
<a name="line-4"></a>
<a name="line-5"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Streams</span><span class='hs-varop'>.</span><span class='hs-conid'>List</span>
<a name="line-6"></a> <span class='hs-layout'>(</span> <span class='hs-comment'>-- * List conversions</span>
<a name="line-7"></a> <span class='hs-varid'>fromList</span>
<a name="line-8"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>toList</span>
<a name="line-9"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>outputToList</span>
<a name="line-10"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>writeList</span>
<a name="line-11"></a>
<a name="line-12"></a> <span class='hs-comment'>-- * Utility</span>
<a name="line-13"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>chunkList</span>
<a name="line-14"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>concatLists</span>
<a name="line-15"></a> <span class='hs-layout'>,</span> <span class='hs-varid'>listOutputStream</span>
<a name="line-16"></a> <span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-17"></a>
<a name="line-18"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-19"></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-varop'>.</span><span class='hs-conid'>MVar</span> <span class='hs-layout'>(</span><span class='hs-varid'>modifyMVar</span><span class='hs-layout'>,</span> <span class='hs-varid'>modifyMVar_</span><span class='hs-layout'>,</span> <span class='hs-varid'>newMVar</span><span class='hs-layout'>)</span>
<a name="line-20"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>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-21"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Data</span><span class='hs-varop'>.</span><span class='hs-conid'>IORef</span> <span class='hs-layout'>(</span><span class='hs-varid'>newIORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>readIORef</span><span class='hs-layout'>,</span> <span class='hs-varid'>writeIORef</span><span class='hs-layout'>)</span>
<a name="line-22"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span> <span class='hs-varid'>hiding</span> <span class='hs-layout'>(</span><span class='hs-varid'>read</span><span class='hs-layout'>)</span>
<a name="line-23"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-24"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>IO</span><span class='hs-varop'>.</span><span class='hs-conid'>Streams</span><span class='hs-varop'>.</span><span class='hs-conid'>Internal</span> <span class='hs-layout'>(</span><span class='hs-conid'>InputStream</span><span class='hs-layout'>,</span> <span class='hs-conid'>OutputStream</span><span class='hs-layout'>,</span> <span class='hs-varid'>await</span><span class='hs-layout'>,</span> <span class='hs-varid'>connect</span><span class='hs-layout'>,</span> <span class='hs-varid'>fromConsumer</span><span class='hs-layout'>,</span> <span class='hs-varid'>fromGenerator</span><span class='hs-layout'>,</span> <span class='hs-varid'>makeInputStream</span><span class='hs-layout'>,</span> <span class='hs-varid'>read</span><span class='hs-layout'>,</span> <span class='hs-varid'>write</span><span class='hs-layout'>,</span> <span class='hs-varid'>yield</span><span class='hs-layout'>)</span>
<a name="line-25"></a>
<a name="line-26"></a>
<a name="line-27"></a><a name="fromList"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-28"></a><span class='hs-comment'>-- | Transforms a list into an 'InputStream' that produces no side effects.</span>
<a name="line-29"></a><span class='hs-comment'>--</span>
<a name="line-30"></a><span class='hs-comment'>-- @</span>
<a name="line-31"></a><span class='hs-comment'>-- ghci> is <- Streams.'fromList' [1, 2]</span>
<a name="line-32"></a><span class='hs-comment'>-- ghci> 'replicateM' 3 (Streams.'read' is)</span>
<a name="line-33"></a><span class='hs-comment'>-- [Just 1, Just 2, Nothing]</span>
<a name="line-34"></a><span class='hs-comment'>-- @</span>
<a name="line-35"></a><span class='hs-definition'>fromList</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>c</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>InputStream</span> <span class='hs-varid'>c</span><span class='hs-layout'>)</span>
<a name="line-36"></a><span class='hs-definition'>fromList</span> <span class='hs-varid'>inp</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>newIORef</span> <span class='hs-varid'>inp</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>makeInputStream</span> <span class='hs-varop'>.</span> <span class='hs-varid'>f</span>
<a name="line-37"></a> <span class='hs-keyword'>where</span>
<a name="line-38"></a> <span class='hs-varid'>f</span> <span class='hs-varid'>ref</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>readIORef</span> <span class='hs-varid'>ref</span> <span class='hs-varop'>>>=</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>l</span> <span class='hs-keyglyph'>-></span>
<a name="line-39"></a> <span class='hs-keyword'>case</span> <span class='hs-varid'>l</span> <span class='hs-keyword'>of</span>
<a name="line-40"></a> <span class='hs-conid'>[]</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-conid'>Nothing</span>
<a name="line-41"></a> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-varid'>xs</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>writeIORef</span> <span class='hs-varid'>ref</span> <span class='hs-varid'>xs</span> <span class='hs-varop'>>></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-conid'>Just</span> <span class='hs-varid'>x</span><span class='hs-layout'>)</span>
<a name="line-42"></a><span class='hs-comment'>{-# INLINE fromList #-}</span>
<a name="line-43"></a>
<a name="line-44"></a>
<a name="line-45"></a><a name="listOutputStream"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-46"></a><span class='hs-comment'>-- | 'listOutputStream' returns an 'OutputStream' which stores values fed into</span>
<a name="line-47"></a><span class='hs-comment'>-- it and an action which flushes all stored values to a list.</span>
<a name="line-48"></a><span class='hs-comment'>--</span>
<a name="line-49"></a><span class='hs-comment'>-- The flush action resets the store.</span>
<a name="line-50"></a><span class='hs-comment'>--</span>
<a name="line-51"></a><span class='hs-comment'>-- Note that this function /will/ buffer any input sent to it on the heap.</span>
<a name="line-52"></a><span class='hs-comment'>-- Please don't use this unless you're sure that the amount of input provided</span>
<a name="line-53"></a><span class='hs-comment'>-- is bounded and will fit in memory without issues.</span>
<a name="line-54"></a><span class='hs-comment'>--</span>
<a name="line-55"></a><span class='hs-comment'>-- @</span>
<a name="line-56"></a><span class='hs-comment'>-- ghci> (os, flush) <- Streams.'listOutputStream' :: IO ('OutputStream' Int, IO [Int])</span>
<a name="line-57"></a><span class='hs-comment'>-- ghci> Streams.'writeList' [1, 2] os</span>
<a name="line-58"></a><span class='hs-comment'>-- ghci> flush</span>
<a name="line-59"></a><span class='hs-comment'>-- [1, 2]</span>
<a name="line-60"></a><span class='hs-comment'>-- ghci> Streams.'writeList' [3, 4] os</span>
<a name="line-61"></a><span class='hs-comment'>-- ghci> flush</span>
<a name="line-62"></a><span class='hs-comment'>-- [3, 4]</span>
<a name="line-63"></a><span class='hs-comment'>-- @</span>
<a name="line-64"></a><span class='hs-definition'>listOutputStream</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>OutputStream</span> <span class='hs-varid'>c</span><span class='hs-layout'>,</span> <span class='hs-conid'>IO</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>c</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span>
<a name="line-65"></a><span class='hs-definition'>listOutputStream</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-66"></a> <span class='hs-varid'>r</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>newMVar</span> <span class='hs-varid'>id</span>
<a name="line-67"></a> <span class='hs-varid'>c</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>fromConsumer</span> <span class='hs-varop'>$</span> <span class='hs-varid'>consumer</span> <span class='hs-varid'>r</span>
<a name="line-68"></a> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-layout'>,</span> <span class='hs-varid'>flush</span> <span class='hs-varid'>r</span><span class='hs-layout'>)</span>
<a name="line-69"></a>
<a name="line-70"></a> <span class='hs-keyword'>where</span>
<a name="line-71"></a> <span class='hs-varid'>consumer</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span>
<a name="line-72"></a> <span class='hs-keyword'>where</span>
<a name="line-73"></a> <span class='hs-varid'>go</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>await</span> <span class='hs-varop'>>>=</span> <span class='hs-layout'>(</span><span class='hs-varid'>maybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varop'>$!</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>c</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-74"></a> <span class='hs-varid'>liftIO</span> <span class='hs-varop'>$</span> <span class='hs-varid'>modifyMVar_</span> <span class='hs-varid'>r</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>dl</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>dl</span> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-varid'>c</span><span class='hs-conop'>:</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-75"></a> <span class='hs-varid'>go</span><span class='hs-layout'>)</span>
<a name="line-76"></a>
<a name="line-77"></a> <span class='hs-varid'>flush</span> <span class='hs-varid'>r</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>modifyMVar</span> <span class='hs-varid'>r</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>dl</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>return</span> <span class='hs-layout'>(</span><span class='hs-varid'>id</span><span class='hs-layout'>,</span> <span class='hs-varid'>dl</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span>
<a name="line-78"></a><span class='hs-comment'>{-# INLINE listOutputStream #-}</span>
<a name="line-79"></a>
<a name="line-80"></a>
<a name="line-81"></a><a name="toList"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-82"></a><span class='hs-comment'>-- | Drains an 'InputStream', converting it to a list. N.B. that this function</span>
<a name="line-83"></a><span class='hs-comment'>-- reads the entire 'InputStream' strictly into memory and as such is not</span>
<a name="line-84"></a><span class='hs-comment'>-- recommended for streaming applications or where the size of the input is not</span>
<a name="line-85"></a><span class='hs-comment'>-- bounded or known.</span>
<a name="line-86"></a><span class='hs-comment'>--</span>
<a name="line-87"></a><span class='hs-comment'>-- @</span>
<a name="line-88"></a><span class='hs-comment'>-- ghci> is <- Streams.'fromList' [1, 2]</span>
<a name="line-89"></a><span class='hs-comment'>-- ghci> Streams.'toList' is</span>
<a name="line-90"></a><span class='hs-comment'>-- [1, 2]</span>
<a name="line-91"></a><span class='hs-comment'>-- @</span>
<a name="line-92"></a><span class='hs-definition'>toList</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>InputStream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-93"></a><span class='hs-definition'>toList</span> <span class='hs-varid'>is</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>outputToList</span> <span class='hs-layout'>(</span><span class='hs-varid'>connect</span> <span class='hs-varid'>is</span><span class='hs-layout'>)</span>
<a name="line-94"></a><span class='hs-comment'>{-# INLINE toList #-}</span>
<a name="line-95"></a>
<a name="line-96"></a>
<a name="line-97"></a><a name="outputToList"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-98"></a><span class='hs-comment'>-- | Given an IO action that requires an 'OutputStream', creates one and</span>
<a name="line-99"></a><span class='hs-comment'>-- captures all the output the action sends to it as a list.</span>
<a name="line-100"></a><span class='hs-comment'>--</span>
<a name="line-101"></a><span class='hs-comment'>-- Example:</span>
<a name="line-102"></a><span class='hs-comment'>--</span>
<a name="line-103"></a><span class='hs-comment'>-- @</span>
<a name="line-104"></a><span class='hs-comment'>-- ghci> import "Control.Applicative"</span>
<a name="line-105"></a><span class='hs-comment'>-- ghci> ('connect' <$> 'fromList' [\"a\", \"b\", \"c\"]) >>= 'outputToList'</span>
<a name="line-106"></a><span class='hs-comment'>-- [\"a\",\"b\",\"c\"]</span>
<a name="line-107"></a><span class='hs-comment'>-- @</span>
<a name="line-108"></a><span class='hs-definition'>outputToList</span> <span class='hs-keyglyph'>::</span> <span class='hs-layout'>(</span><span class='hs-conid'>OutputStream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-varid'>b</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span>
<a name="line-109"></a><span class='hs-definition'>outputToList</span> <span class='hs-varid'>f</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-110"></a> <span class='hs-layout'>(</span><span class='hs-varid'>os</span><span class='hs-layout'>,</span> <span class='hs-varid'>getList</span><span class='hs-layout'>)</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>listOutputStream</span>
<a name="line-111"></a> <span class='hs-keyword'>_</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>f</span> <span class='hs-varid'>os</span>
<a name="line-112"></a> <span class='hs-varid'>getList</span>
<a name="line-113"></a><span class='hs-comment'>{-# INLINE outputToList #-}</span>
<a name="line-114"></a>
<a name="line-115"></a>
<a name="line-116"></a><a name="writeList"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-117"></a><span class='hs-comment'>-- | Feeds a list to an 'OutputStream'. Does /not/ write an end-of-stream to</span>
<a name="line-118"></a><span class='hs-comment'>-- the stream.</span>
<a name="line-119"></a><span class='hs-comment'>--</span>
<a name="line-120"></a><span class='hs-comment'>-- @</span>
<a name="line-121"></a><span class='hs-comment'>-- ghci> os \<- Streams.'unlines' Streams.'System.IO.Streams.stdout' >>= Streams.'System.IO.Streams.contramap' (S.pack . show) :: IO ('OutputStream' Int)</span>
<a name="line-122"></a><span class='hs-comment'>-- ghci> Streams.'writeList' [1, 2] os</span>
<a name="line-123"></a><span class='hs-comment'>-- 1</span>
<a name="line-124"></a><span class='hs-comment'>-- 2</span>
<a name="line-125"></a><span class='hs-comment'>-- ghci> Streams.'writeList' [3, 4] os</span>
<a name="line-126"></a><span class='hs-comment'>-- 3</span>
<a name="line-127"></a><span class='hs-comment'>-- 4</span>
<a name="line-128"></a><span class='hs-comment'>-- @</span>
<a name="line-129"></a><span class='hs-definition'>writeList</span> <span class='hs-keyglyph'>::</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>OutputStream</span> <span class='hs-varid'>a</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-130"></a><span class='hs-definition'>writeList</span> <span class='hs-varid'>xs</span> <span class='hs-varid'>os</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>mapM_</span> <span class='hs-layout'>(</span><span class='hs-varid'>flip</span> <span class='hs-varid'>write</span> <span class='hs-varid'>os</span> <span class='hs-varop'>.</span> <span class='hs-conid'>Just</span><span class='hs-layout'>)</span> <span class='hs-varid'>xs</span>
<a name="line-131"></a><span class='hs-comment'>{-# INLINE writeList #-}</span>
<a name="line-132"></a>
<a name="line-133"></a>
<a name="line-134"></a><a name="chunkList"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-135"></a><span class='hs-comment'>-- | Splits an input stream into chunks of at most size @n@.</span>
<a name="line-136"></a><span class='hs-comment'>--</span>
<a name="line-137"></a><span class='hs-comment'>-- Example:</span>
<a name="line-138"></a><span class='hs-comment'>--</span>
<a name="line-139"></a><span class='hs-comment'>-- @</span>
<a name="line-140"></a><span class='hs-comment'>-- ghci> 'fromList' [1..14::Int] >>= 'chunkList' 4 >>= 'toList'</span>
<a name="line-141"></a><span class='hs-comment'>-- [[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14]]</span>
<a name="line-142"></a><span class='hs-comment'>-- @</span>
<a name="line-143"></a><span class='hs-definition'>chunkList</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>Int</span> <span class='hs-comment'>-- ^ chunk size</span>
<a name="line-144"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>InputStream</span> <span class='hs-varid'>a</span> <span class='hs-comment'>-- ^ stream to process</span>
<a name="line-145"></a> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>InputStream</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span><span class='hs-layout'>)</span>
<a name="line-146"></a><span class='hs-definition'>chunkList</span> <span class='hs-varid'>n</span> <span class='hs-varid'>input</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>n</span> <span class='hs-varop'><=</span> <span class='hs-num'>0</span>
<a name="line-147"></a> <span class='hs-keyword'>then</span> <span class='hs-varid'>error</span> <span class='hs-varop'>$</span> <span class='hs-str'>"chunkList: bad size: "</span> <span class='hs-varop'>++</span> <span class='hs-varid'>show</span> <span class='hs-varid'>n</span>
<a name="line-148"></a> <span class='hs-keyword'>else</span> <span class='hs-varid'>fromGenerator</span> <span class='hs-varop'>$</span> <span class='hs-varid'>go</span> <span class='hs-varid'>n</span> <span class='hs-varid'>id</span>
<a name="line-149"></a> <span class='hs-keyword'>where</span>
<a name="line-150"></a> <span class='hs-varid'>go</span> <span class='hs-varop'>!</span><span class='hs-varid'>k</span> <span class='hs-varid'>dl</span> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>k</span> <span class='hs-varop'><=</span> <span class='hs-num'>0</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>yield</span> <span class='hs-layout'>(</span><span class='hs-varid'>dl</span> <span class='hs-conid'>[]</span><span class='hs-layout'>)</span> <span class='hs-varop'>>></span> <span class='hs-varid'>go</span> <span class='hs-varid'>n</span> <span class='hs-varid'>id</span>
<a name="line-151"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>do</span>
<a name="line-152"></a> <span class='hs-varid'>liftIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>read</span> <span class='hs-varid'>input</span><span class='hs-layout'>)</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>maybe</span> <span class='hs-varid'>finish</span> <span class='hs-varid'>chunk</span>
<a name="line-153"></a> <span class='hs-keyword'>where</span>
<a name="line-154"></a> <span class='hs-varid'>finish</span> <span class='hs-keyglyph'>=</span> <span class='hs-keyword'>let</span> <span class='hs-varid'>l</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>dl</span> <span class='hs-conid'>[]</span>
<a name="line-155"></a> <span class='hs-keyword'>in</span> <span class='hs-keyword'>if</span> <span class='hs-varid'>null</span> <span class='hs-varid'>l</span> <span class='hs-keyword'>then</span> <span class='hs-varid'>return</span> <span class='hs-varop'>$!</span> <span class='hs-conid'>()</span> <span class='hs-keyword'>else</span> <span class='hs-varid'>yield</span> <span class='hs-varid'>l</span>
<a name="line-156"></a> <span class='hs-varid'>chunk</span> <span class='hs-varid'>x</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>go</span> <span class='hs-layout'>(</span><span class='hs-varid'>k</span> <span class='hs-comment'>-</span> <span class='hs-num'>1</span><span class='hs-layout'>)</span> <span class='hs-layout'>(</span><span class='hs-varid'>dl</span> <span class='hs-varop'>.</span> <span class='hs-layout'>(</span><span class='hs-varid'>x</span><span class='hs-conop'>:</span><span class='hs-layout'>)</span><span class='hs-layout'>)</span>
<a name="line-157"></a>
<a name="line-158"></a>
<a name="line-159"></a><a name="concatLists"></a><span class='hs-comment'>------------------------------------------------------------------------------</span>
<a name="line-160"></a><span class='hs-comment'>-- | Given an input stream containing lists, produces a new input stream that</span>
<a name="line-161"></a><span class='hs-comment'>-- will yield the concatenation of these lists. See 'Prelude.concat'.</span>
<a name="line-162"></a><span class='hs-comment'>--</span>
<a name="line-163"></a><span class='hs-comment'>-- Example:</span>
<a name="line-164"></a><span class='hs-comment'>--</span>
<a name="line-165"></a><span class='hs-comment'>-- @</span>
<a name="line-166"></a><span class='hs-comment'>-- ghci> Streams.'fromList' [[1,2,3::Int], [4,5,6]] >>=</span>
<a name="line-167"></a><span class='hs-comment'>-- Streams.'concatLists' >>=</span>
<a name="line-168"></a><span class='hs-comment'>-- Streams.'toList'</span>
<a name="line-169"></a><span class='hs-comment'>-- [1,2,3,4,5,6]</span>
<a name="line-170"></a><span class='hs-comment'>-- @</span>
<a name="line-171"></a><span class='hs-definition'>concatLists</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>InputStream</span> <span class='hs-keyglyph'>[</span><span class='hs-varid'>a</span><span class='hs-keyglyph'>]</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>InputStream</span> <span class='hs-varid'>a</span><span class='hs-layout'>)</span>
<a name="line-172"></a><span class='hs-definition'>concatLists</span> <span class='hs-varid'>input</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>fromGenerator</span> <span class='hs-varid'>go</span>
<a name="line-173"></a> <span class='hs-keyword'>where</span>
<a name="line-174"></a> <span class='hs-varid'>go</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>liftIO</span> <span class='hs-layout'>(</span><span class='hs-varid'>read</span> <span class='hs-varid'>input</span><span class='hs-layout'>)</span> <span class='hs-varop'>>>=</span> <span class='hs-varid'>maybe</span> <span class='hs-layout'>(</span><span class='hs-varid'>return</span> <span class='hs-varop'>$!</span> <span class='hs-conid'>()</span><span class='hs-layout'>)</span> <span class='hs-varid'>chunk</span>
<a name="line-175"></a> <span class='hs-varid'>chunk</span> <span class='hs-varid'>l</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>sequence_</span> <span class='hs-layout'>(</span><span class='hs-varid'>map</span> <span class='hs-varid'>yield</span> <span class='hs-varid'>l</span><span class='hs-layout'>)</span> <span class='hs-varop'>>></span> <span class='hs-varid'>go</span>
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