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<pre><a name="line-1"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-2"></a>
<a name="line-3"></a><span class='comment'>{- |
<a name="line-4"></a> Module : Control.Arrow.ListArrow
<a name="line-5"></a> Copyright : Copyright (C) 2005 Uwe Schmidt
<a name="line-6"></a> License : MIT
<a name="line-7"></a>
<a name="line-8"></a> Maintainer : Uwe Schmidt (uwe\@fh-wedel.de)
<a name="line-9"></a> Stability : experimental
<a name="line-10"></a> Portability: portable
<a name="line-11"></a> Version : $Id: ListArrow.hs,v 1.7 2006/05/04 14:17:53 hxml Exp $
<a name="line-12"></a>
<a name="line-13"></a>Implementation of pure list arrows
<a name="line-14"></a>
<a name="line-15"></a>-}</span>
<a name="line-16"></a>
<a name="line-17"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-18"></a>
<a name="line-19"></a><span class='keyword'>module</span> <span class='conid'>Control</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>ListArrow</span>
<a name="line-20"></a> <span class='layout'>(</span> <span class='conid'>LA</span><span class='layout'>(</span><span class='keyglyph'>..</span><span class='layout'>)</span>
<a name="line-21"></a> <span class='layout'>,</span> <span class='varid'>fromLA</span>
<a name="line-22"></a> <span class='layout'>)</span>
<a name="line-23"></a><span class='keyword'>where</span>
<a name="line-24"></a>
<a name="line-25"></a><span class='keyword'>import</span> <span class='conid'>Control</span><span class='varop'>.</span><span class='conid'>Arrow</span>
<a name="line-26"></a><span class='keyword'>import</span> <span class='conid'>Control</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>ArrowList</span>
<a name="line-27"></a><span class='keyword'>import</span> <span class='conid'>Control</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>ArrowIf</span>
<a name="line-28"></a><span class='keyword'>import</span> <span class='conid'>Control</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>ArrowTree</span>
<a name="line-29"></a>
<a name="line-30"></a><span class='keyword'>import</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>List</span>
<a name="line-31"></a> <span class='layout'>(</span> <span class='varid'>partition</span> <span class='layout'>)</span>
<a name="line-32"></a>
<a name="line-33"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-34"></a>
<a name="line-35"></a><span class='comment'>-- | pure list arrow data type</span>
<a name="line-36"></a>
<a name="line-37"></a><a name="LA"></a><span class='keyword'>newtype</span> <span class='conid'>LA</span> <span class='varid'>a</span> <span class='varid'>b</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='layout'>{</span> <span class='varid'>runLA</span> <span class='keyglyph'>::</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='varid'>b</span><span class='keyglyph'>]</span> <span class='layout'>}</span>
<a name="line-38"></a>
<a name="line-39"></a><span class='keyword'>instance</span> <span class='conid'>Arrow</span> <span class='conid'>LA</span> <span class='keyword'>where</span>
<a name="line-40"></a> <span class='varid'>arr</span> <span class='varid'>f</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='varid'>f</span> <span class='varid'>x</span><span class='keyglyph'>]</span>
<a name="line-41"></a> <span class='conid'>LA</span> <span class='varid'>f</span> <span class='varop'>>>></span> <span class='conid'>LA</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='varid'>concatMap</span> <span class='varid'>g</span> <span class='varop'>.</span> <span class='varid'>f</span>
<a name="line-42"></a> <span class='varid'>first</span> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>x1</span><span class='layout'>,</span> <span class='varid'>x2</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span> <span class='layout'>(</span><span class='varid'>y1</span><span class='layout'>,</span> <span class='varid'>x2</span><span class='layout'>)</span> <span class='keyglyph'>|</span> <span class='varid'>y1</span> <span class='keyglyph'><-</span> <span class='varid'>f</span> <span class='varid'>x1</span> <span class='keyglyph'>]</span>
<a name="line-43"></a>
<a name="line-44"></a> <span class='comment'>-- just for efficiency</span>
<a name="line-45"></a>
<a name="line-46"></a> <span class='varid'>second</span> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>g</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>x1</span><span class='layout'>,</span> <span class='varid'>x2</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span> <span class='layout'>(</span><span class='varid'>x1</span><span class='layout'>,</span> <span class='varid'>y2</span><span class='layout'>)</span> <span class='keyglyph'>|</span> <span class='varid'>y2</span> <span class='keyglyph'><-</span> <span class='varid'>g</span> <span class='varid'>x2</span> <span class='keyglyph'>]</span>
<a name="line-47"></a> <span class='conid'>LA</span> <span class='varid'>f</span> <span class='varop'>***</span> <span class='conid'>LA</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>x1</span><span class='layout'>,</span> <span class='varid'>x2</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span> <span class='layout'>(</span><span class='varid'>y1</span><span class='layout'>,</span> <span class='varid'>y2</span><span class='layout'>)</span> <span class='keyglyph'>|</span> <span class='varid'>y1</span> <span class='keyglyph'><-</span> <span class='varid'>f</span> <span class='varid'>x1</span><span class='layout'>,</span> <span class='varid'>y2</span> <span class='keyglyph'><-</span> <span class='varid'>g</span> <span class='varid'>x2</span><span class='keyglyph'>]</span>
<a name="line-48"></a> <span class='conid'>LA</span> <span class='varid'>f</span> <span class='varop'>&&&</span> <span class='conid'>LA</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span> <span class='layout'>(</span><span class='varid'>y1</span><span class='layout'>,</span> <span class='varid'>y2</span><span class='layout'>)</span> <span class='keyglyph'>|</span> <span class='varid'>y1</span> <span class='keyglyph'><-</span> <span class='varid'>f</span> <span class='varid'>x</span> <span class='layout'>,</span> <span class='varid'>y2</span> <span class='keyglyph'><-</span> <span class='varid'>g</span> <span class='varid'>x</span> <span class='keyglyph'>]</span>
<a name="line-49"></a>
<a name="line-50"></a><span class='keyword'>instance</span> <span class='conid'>ArrowZero</span> <span class='conid'>LA</span> <span class='keyword'>where</span>
<a name="line-51"></a> <span class='varid'>zeroArrow</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='varid'>const</span> <span class='conid'>[]</span>
<a name="line-52"></a>
<a name="line-53"></a>
<a name="line-54"></a><span class='keyword'>instance</span> <span class='conid'>ArrowPlus</span> <span class='conid'>LA</span> <span class='keyword'>where</span>
<a name="line-55"></a> <span class='conid'>LA</span> <span class='varid'>f</span> <span class='varop'><+></span> <span class='conid'>LA</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='varid'>f</span> <span class='varid'>x</span> <span class='varop'>++</span> <span class='varid'>g</span> <span class='varid'>x</span>
<a name="line-56"></a>
<a name="line-57"></a>
<a name="line-58"></a><span class='keyword'>instance</span> <span class='conid'>ArrowChoice</span> <span class='conid'>LA</span> <span class='keyword'>where</span>
<a name="line-59"></a> <span class='varid'>left</span> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='varid'>either</span> <span class='layout'>(</span><span class='varid'>map</span> <span class='conid'>Left</span> <span class='varop'>.</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='layout'>(</span><span class='layout'>(</span><span class='conop'>:</span><span class='conid'>[]</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='conid'>Right</span><span class='layout'>)</span>
<a name="line-60"></a> <span class='varid'>right</span> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='varid'>either</span> <span class='layout'>(</span><span class='layout'>(</span><span class='conop'>:</span><span class='conid'>[]</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='conid'>Left</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>map</span> <span class='conid'>Right</span> <span class='varop'>.</span> <span class='varid'>f</span><span class='layout'>)</span>
<a name="line-61"></a> <span class='conid'>LA</span> <span class='varid'>f</span> <span class='varop'>+++</span> <span class='conid'>LA</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='varid'>either</span> <span class='layout'>(</span><span class='varid'>map</span> <span class='conid'>Left</span> <span class='varop'>.</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>map</span> <span class='conid'>Right</span> <span class='varop'>.</span> <span class='varid'>g</span><span class='layout'>)</span>
<a name="line-62"></a> <span class='conid'>LA</span> <span class='varid'>f</span> <span class='varop'>|||</span> <span class='conid'>LA</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='varid'>either</span> <span class='varid'>f</span> <span class='varid'>g</span>
<a name="line-63"></a>
<a name="line-64"></a>
<a name="line-65"></a><span class='keyword'>instance</span> <span class='conid'>ArrowApply</span> <span class='conid'>LA</span> <span class='keyword'>where</span>
<a name="line-66"></a> <span class='varid'>app</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>f</span><span class='layout'>,</span> <span class='varid'>x</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='varid'>f</span> <span class='varid'>x</span>
<a name="line-67"></a>
<a name="line-68"></a><span class='keyword'>instance</span> <span class='conid'>ArrowList</span> <span class='conid'>LA</span> <span class='keyword'>where</span>
<a name="line-69"></a> <span class='varid'>arrL</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span>
<a name="line-70"></a> <span class='varid'>arr2A</span> <span class='varid'>f</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>x</span><span class='layout'>,</span> <span class='varid'>y</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='varid'>runLA</span> <span class='layout'>(</span><span class='varid'>f</span> <span class='varid'>x</span><span class='layout'>)</span> <span class='varid'>y</span>
<a name="line-71"></a> <span class='varid'>isA</span> <span class='varid'>p</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='keyword'>if</span> <span class='varid'>p</span> <span class='varid'>x</span> <span class='keyword'>then</span> <span class='keyglyph'>[</span><span class='varid'>x</span><span class='keyglyph'>]</span> <span class='keyword'>else</span> <span class='conid'>[]</span>
<a name="line-72"></a> <span class='conid'>LA</span> <span class='varid'>f</span> <span class='varop'>>>.</span> <span class='varid'>g</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='varid'>g</span> <span class='varop'>.</span> <span class='varid'>f</span>
<a name="line-73"></a> <span class='varid'>withDefault</span> <span class='varid'>a</span> <span class='varid'>d</span> <span class='keyglyph'>=</span> <span class='varid'>a</span> <span class='varop'>>>.</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='keyword'>if</span> <span class='varid'>null</span> <span class='varid'>x</span> <span class='keyword'>then</span> <span class='keyglyph'>[</span><span class='varid'>d</span><span class='keyglyph'>]</span> <span class='keyword'>else</span> <span class='varid'>x</span>
<a name="line-74"></a>
<a name="line-75"></a>
<a name="line-76"></a><span class='keyword'>instance</span> <span class='conid'>ArrowIf</span> <span class='conid'>LA</span> <span class='keyword'>where</span>
<a name="line-77"></a> <span class='varid'>ifA</span> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>p</span><span class='layout'>)</span> <span class='varid'>t</span> <span class='varid'>e</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='varid'>runLA</span> <span class='layout'>(</span> <span class='keyword'>if</span> <span class='varid'>null</span> <span class='layout'>(</span><span class='varid'>p</span> <span class='varid'>x</span><span class='layout'>)</span>
<a name="line-78"></a> <span class='keyword'>then</span> <span class='varid'>e</span>
<a name="line-79"></a> <span class='keyword'>else</span> <span class='varid'>t</span>
<a name="line-80"></a> <span class='layout'>)</span> <span class='varid'>x</span>
<a name="line-81"></a>
<a name="line-82"></a> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='varop'>`orElse`</span> <span class='layout'>(</span><span class='conid'>LA</span> <span class='varid'>g</span><span class='layout'>)</span>
<a name="line-83"></a> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='layout'>(</span> <span class='keyword'>let</span>
<a name="line-84"></a> <span class='varid'>res</span> <span class='keyglyph'>=</span> <span class='varid'>f</span> <span class='varid'>x</span>
<a name="line-85"></a> <span class='keyword'>in</span>
<a name="line-86"></a> <span class='keyword'>if</span> <span class='varid'>null</span> <span class='varid'>res</span>
<a name="line-87"></a> <span class='keyword'>then</span> <span class='varid'>g</span> <span class='varid'>x</span>
<a name="line-88"></a> <span class='keyword'>else</span> <span class='varid'>res</span>
<a name="line-89"></a> <span class='layout'>)</span>
<a name="line-90"></a>
<a name="line-91"></a> <span class='varid'>spanA</span> <span class='varid'>p</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='layout'>(</span><span class='conop'>:</span><span class='conid'>[]</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='varid'>span</span> <span class='layout'>(</span><span class='varid'>not</span> <span class='varop'>.</span> <span class='varid'>null</span> <span class='varop'>.</span> <span class='varid'>runLA</span> <span class='varid'>p</span><span class='layout'>)</span>
<a name="line-92"></a>
<a name="line-93"></a> <span class='varid'>partitionA</span> <span class='varid'>p</span> <span class='keyglyph'>=</span> <span class='conid'>LA</span> <span class='varop'>$</span> <span class='layout'>(</span><span class='conop'>:</span><span class='conid'>[]</span><span class='layout'>)</span> <span class='varop'>.</span> <span class='varid'>partition</span> <span class='layout'>(</span><span class='varid'>not</span> <span class='varop'>.</span> <span class='varid'>null</span> <span class='varop'>.</span> <span class='varid'>runLA</span> <span class='varid'>p</span><span class='layout'>)</span>
<a name="line-94"></a>
<a name="line-95"></a><span class='keyword'>instance</span> <span class='conid'>ArrowTree</span> <span class='conid'>LA</span>
<a name="line-96"></a>
<a name="line-97"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-98"></a>
<a name="line-99"></a><span class='comment'>-- | conversion of pure list arrows into other possibly more complex</span>
<a name="line-100"></a><span class='comment'>-- list arrows</span>
<a name="line-101"></a>
<a name="line-102"></a><a name="fromLA"></a><span class='definition'>fromLA</span> <span class='keyglyph'>::</span> <span class='conid'>ArrowList</span> <span class='varid'>a</span> <span class='keyglyph'>=></span> <span class='conid'>LA</span> <span class='varid'>b</span> <span class='varid'>c</span> <span class='keyglyph'>-></span> <span class='varid'>a</span> <span class='varid'>b</span> <span class='varid'>c</span>
<a name="line-103"></a><span class='definition'>fromLA</span> <span class='varid'>f</span> <span class='keyglyph'>=</span> <span class='varid'>arrL</span> <span class='layout'>(</span><span class='varid'>runLA</span> <span class='varid'>f</span><span class='layout'>)</span>
<a name="line-104"></a>
<a name="line-105"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-106"></a>
</pre></body>
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