hxt-8.0.0: doc/hdoc/src/Text-XML-HXT-Arrow-Pickle-Xml.html
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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 : Text.XML.HXT.Arrow.Pickle.Xml
<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 : $Id$
<a name="line-12"></a>
<a name="line-13"></a>Pickler functions for converting between user defined data types
<a name="line-14"></a>and XmlTree data. Usefull for persistent storage and retreival
<a name="line-15"></a>of arbitray data as XML documents
<a name="line-16"></a>
<a name="line-17"></a>This module is an adaptation of the pickler combinators
<a name="line-18"></a>developed by Andrew Kennedy
<a name="line-19"></a>( http:\/\/research.microsoft.com\/~akenn\/fun\/picklercombinators.pdf )
<a name="line-20"></a>
<a name="line-21"></a>The difference to Kennedys approach is that the target is not
<a name="line-22"></a>a list of Chars but a list of XmlTrees. The basic picklers will
<a name="line-23"></a>convert data into XML text nodes. New are the picklers for
<a name="line-24"></a>creating elements and attributes.
<a name="line-25"></a>
<a name="line-26"></a>One extension was neccessary: The unpickling may fail.
<a name="line-27"></a>Therefore the unpickler has a Maybe result type.
<a name="line-28"></a>Failure is used to unpickle optional elements
<a name="line-29"></a>(Maybe data) and lists of arbitray length
<a name="line-30"></a>
<a name="line-31"></a>There is an example program demonstrating the use
<a name="line-32"></a>of the picklers for a none trivial data structure.
<a name="line-33"></a>(see \"examples\/arrows\/pickle\" directory)
<a name="line-34"></a>
<a name="line-35"></a>-}</span>
<a name="line-36"></a>
<a name="line-37"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-38"></a>
<a name="line-39"></a><span class='keyword'>module</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>Pickle</span><span class='varop'>.</span><span class='conid'>Xml</span>
<a name="line-40"></a><span class='keyword'>where</span>
<a name="line-41"></a>
<a name="line-42"></a><span class='keyword'>import</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>Maybe</span>
<a name="line-43"></a>
<a name="line-44"></a><span class='keyword'>import</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>DOM</span><span class='varop'>.</span><span class='conid'>Interface</span>
<a name="line-45"></a><span class='keyword'>import</span> <span class='keyword'>qualified</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>DOM</span><span class='varop'>.</span><span class='conid'>XmlNode</span> <span class='keyword'>as</span> <span class='conid'>XN</span>
<a name="line-46"></a>
<a name="line-47"></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'>ListArrows</span>
<a name="line-48"></a><span class='keyword'>import</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>XmlArrow</span>
<a name="line-49"></a><span class='keyword'>import</span> <span class='conid'>Text</span><span class='varop'>.</span><span class='conid'>XML</span><span class='varop'>.</span><span class='conid'>HXT</span><span class='varop'>.</span><span class='conid'>Arrow</span><span class='varop'>.</span><span class='conid'>Pickle</span><span class='varop'>.</span><span class='conid'>Schema</span>
<a name="line-50"></a>
<a name="line-51"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-52"></a>
<a name="line-53"></a><a name="St"></a><span class='keyword'>data</span> <span class='conid'>St</span> <span class='keyglyph'>=</span> <span class='conid'>St</span> <span class='layout'>{</span> <span class='varid'>attributes</span> <span class='keyglyph'>::</span> <span class='keyglyph'>[</span><span class='conid'>XmlTree</span><span class='keyglyph'>]</span>
<a name="line-54"></a> <span class='layout'>,</span> <span class='varid'>contents</span> <span class='keyglyph'>::</span> <span class='keyglyph'>[</span><span class='conid'>XmlTree</span><span class='keyglyph'>]</span>
<a name="line-55"></a> <span class='layout'>}</span>
<a name="line-56"></a>
<a name="line-57"></a><a name="PU"></a><span class='keyword'>data</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='conid'>St</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>St</span>
<a name="line-58"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>::</span> <span class='conid'>St</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='conid'>Maybe</span> <span class='varid'>a</span><span class='layout'>,</span> <span class='conid'>St</span><span class='layout'>)</span>
<a name="line-59"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>::</span> <span class='conid'>Schema</span>
<a name="line-60"></a> <span class='layout'>}</span>
<a name="line-61"></a>
<a name="line-62"></a><a name="emptySt"></a><span class='definition'>emptySt</span> <span class='keyglyph'>::</span> <span class='conid'>St</span>
<a name="line-63"></a><span class='definition'>emptySt</span> <span class='keyglyph'>=</span> <span class='conid'>St</span> <span class='layout'>{</span> <span class='varid'>attributes</span> <span class='keyglyph'>=</span> <span class='conid'>[]</span>
<a name="line-64"></a> <span class='layout'>,</span> <span class='varid'>contents</span> <span class='keyglyph'>=</span> <span class='conid'>[]</span>
<a name="line-65"></a> <span class='layout'>}</span>
<a name="line-66"></a>
<a name="line-67"></a><a name="addAtt"></a><span class='definition'>addAtt</span> <span class='keyglyph'>::</span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>St</span> <span class='keyglyph'>-></span> <span class='conid'>St</span>
<a name="line-68"></a><span class='definition'>addAtt</span> <span class='varid'>x</span> <span class='varid'>s</span> <span class='keyglyph'>=</span> <span class='varid'>s</span> <span class='layout'>{</span><span class='varid'>attributes</span> <span class='keyglyph'>=</span> <span class='varid'>x</span> <span class='conop'>:</span> <span class='varid'>attributes</span> <span class='varid'>s</span><span class='layout'>}</span>
<a name="line-69"></a>
<a name="line-70"></a><a name="addCont"></a><span class='definition'>addCont</span> <span class='keyglyph'>::</span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>St</span> <span class='keyglyph'>-></span> <span class='conid'>St</span>
<a name="line-71"></a><span class='definition'>addCont</span> <span class='varid'>x</span> <span class='varid'>s</span> <span class='keyglyph'>=</span> <span class='varid'>s</span> <span class='layout'>{</span><span class='varid'>contents</span> <span class='keyglyph'>=</span> <span class='varid'>x</span> <span class='conop'>:</span> <span class='varid'>contents</span> <span class='varid'>s</span><span class='layout'>}</span>
<a name="line-72"></a>
<a name="line-73"></a><a name="dropCont"></a><span class='definition'>dropCont</span> <span class='keyglyph'>::</span> <span class='conid'>St</span> <span class='keyglyph'>-></span> <span class='conid'>St</span>
<a name="line-74"></a><span class='definition'>dropCont</span> <span class='varid'>s</span> <span class='keyglyph'>=</span> <span class='varid'>s</span> <span class='layout'>{</span> <span class='varid'>contents</span> <span class='keyglyph'>=</span> <span class='varid'>drop</span> <span class='num'>1</span> <span class='layout'>(</span><span class='varid'>contents</span> <span class='varid'>s</span><span class='layout'>)</span> <span class='layout'>}</span>
<a name="line-75"></a>
<a name="line-76"></a><a name="getAtt"></a><span class='definition'>getAtt</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>St</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='conid'>XmlTree</span>
<a name="line-77"></a><span class='definition'>getAtt</span> <span class='varid'>name</span> <span class='varid'>s</span>
<a name="line-78"></a> <span class='keyglyph'>=</span> <span class='varid'>listToMaybe</span> <span class='varop'>$</span>
<a name="line-79"></a> <span class='varid'>runLA</span> <span class='layout'>(</span> <span class='varid'>arrL</span> <span class='varid'>attributes</span>
<a name="line-80"></a> <span class='varop'>>>></span>
<a name="line-81"></a> <span class='varid'>isAttr</span> <span class='varop'>>>></span> <span class='varid'>hasName</span> <span class='varid'>name</span>
<a name="line-82"></a> <span class='layout'>)</span> <span class='varid'>s</span>
<a name="line-83"></a>
<a name="line-84"></a><a name="getCont"></a><span class='definition'>getCont</span> <span class='keyglyph'>::</span> <span class='conid'>St</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='conid'>XmlTree</span>
<a name="line-85"></a><span class='definition'>getCont</span> <span class='varid'>s</span> <span class='keyglyph'>=</span> <span class='varid'>listToMaybe</span> <span class='varop'>.</span> <span class='varid'>contents</span> <span class='varop'>$</span> <span class='varid'>s</span>
<a name="line-86"></a>
<a name="line-87"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-88"></a>
<a name="line-89"></a><span class='comment'>-- | conversion of an arbitrary value into an XML document tree.</span>
<a name="line-90"></a><span class='comment'>--</span>
<a name="line-91"></a><span class='comment'>-- The pickler, first parameter, controls the conversion process.</span>
<a name="line-92"></a><span class='comment'>-- Result is a complete document tree including a root node</span>
<a name="line-93"></a>
<a name="line-94"></a><a name="pickleDoc"></a><span class='definition'>pickleDoc</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTree</span>
<a name="line-95"></a><span class='definition'>pickleDoc</span> <span class='varid'>p</span> <span class='varid'>v</span>
<a name="line-96"></a> <span class='keyglyph'>=</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>mkRoot</span> <span class='layout'>(</span><span class='varid'>attributes</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>contents</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-97"></a> <span class='keyword'>where</span>
<a name="line-98"></a> <span class='varid'>st</span> <span class='keyglyph'>=</span> <span class='varid'>appPickle</span> <span class='varid'>p</span> <span class='layout'>(</span><span class='varid'>v</span><span class='layout'>,</span> <span class='varid'>emptySt</span><span class='layout'>)</span>
<a name="line-99"></a>
<a name="line-100"></a><span class='comment'>-- | Conversion of an XML document tree into an arbitrary data type</span>
<a name="line-101"></a><span class='comment'>--</span>
<a name="line-102"></a><span class='comment'>-- The inverse of 'pickleDoc'.</span>
<a name="line-103"></a><span class='comment'>-- This law should hold for all picklers: @ unpickle px . pickle px $ v == Just v @.</span>
<a name="line-104"></a><span class='comment'>-- Not every possible combination of picklers make sense.</span>
<a name="line-105"></a><span class='comment'>-- For reconverting a value from an XML tree, is becomes neccessary,</span>
<a name="line-106"></a><span class='comment'>-- to introduce \"enough\" markup for unpickling the value</span>
<a name="line-107"></a>
<a name="line-108"></a><a name="unpickleDoc"></a><span class='definition'>unpickleDoc</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTree</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='varid'>a</span>
<a name="line-109"></a><span class='definition'>unpickleDoc</span> <span class='varid'>p</span> <span class='varid'>t</span>
<a name="line-110"></a> <span class='keyglyph'>|</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>isRoot</span> <span class='varid'>t</span>
<a name="line-111"></a> <span class='keyglyph'>=</span> <span class='varid'>fst</span> <span class='varop'>.</span> <span class='varid'>appUnPickle</span> <span class='varid'>p</span> <span class='varop'>$</span> <span class='conid'>St</span> <span class='layout'>{</span> <span class='varid'>attributes</span> <span class='keyglyph'>=</span> <span class='varid'>fromJust</span> <span class='varop'>.</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>getAttrl</span> <span class='varop'>$</span> <span class='varid'>t</span>
<a name="line-112"></a> <span class='layout'>,</span> <span class='varid'>contents</span> <span class='keyglyph'>=</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>getChildren</span> <span class='varid'>t</span>
<a name="line-113"></a> <span class='layout'>}</span>
<a name="line-114"></a> <span class='keyglyph'>|</span> <span class='varid'>otherwise</span>
<a name="line-115"></a> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-116"></a>
<a name="line-117"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-118"></a>
<a name="line-119"></a><span class='comment'>-- | The zero pickler</span>
<a name="line-120"></a><span class='comment'>--</span>
<a name="line-121"></a><span class='comment'>-- Encodes nothing, fails always during unpickling</span>
<a name="line-122"></a>
<a name="line-123"></a><a name="xpZero"></a><span class='definition'>xpZero</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-124"></a><span class='definition'>xpZero</span> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='varid'>snd</span>
<a name="line-125"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='varid'>s</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='conid'>Nothing</span><span class='layout'>,</span> <span class='varid'>s</span><span class='layout'>)</span>
<a name="line-126"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scNull</span>
<a name="line-127"></a> <span class='layout'>}</span>
<a name="line-128"></a>
<a name="line-129"></a><span class='comment'>-- unit pickler</span>
<a name="line-130"></a>
<a name="line-131"></a><a name="xpUnit"></a><span class='definition'>xpUnit</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='conid'>()</span>
<a name="line-132"></a><span class='definition'>xpUnit</span> <span class='keyglyph'>=</span> <span class='varid'>xpLift</span> <span class='conid'>()</span>
<a name="line-133"></a>
<a name="line-134"></a><span class='comment'>-- | Lift a value to a pickler</span>
<a name="line-135"></a><span class='comment'>--</span>
<a name="line-136"></a><span class='comment'>-- When pickling, nothing is encoded, when unpickling, the given value is inserted.</span>
<a name="line-137"></a><span class='comment'>-- This pickler always succeeds.</span>
<a name="line-138"></a>
<a name="line-139"></a><a name="xpLift"></a><span class='definition'>xpLift</span> <span class='keyglyph'>::</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-140"></a><span class='definition'>xpLift</span> <span class='varid'>x</span> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='varid'>snd</span>
<a name="line-141"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='varid'>s</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varid'>x</span><span class='layout'>,</span> <span class='varid'>s</span><span class='layout'>)</span>
<a name="line-142"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scEmpty</span>
<a name="line-143"></a> <span class='layout'>}</span>
<a name="line-144"></a>
<a name="line-145"></a><span class='comment'>-- | Lift a Maybe value to a pickler.</span>
<a name="line-146"></a><span class='comment'>--</span>
<a name="line-147"></a><span class='comment'>-- @Nothing@ is mapped to the zero pickler, @Just x@ is pickled with @xpLift x@.</span>
<a name="line-148"></a>
<a name="line-149"></a><a name="xpLiftMaybe"></a><span class='definition'>xpLiftMaybe</span> <span class='keyglyph'>::</span> <span class='conid'>Maybe</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-150"></a><span class='definition'>xpLiftMaybe</span> <span class='varid'>v</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>xpLiftMaybe'</span> <span class='varid'>v</span><span class='layout'>)</span> <span class='layout'>{</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scOption</span> <span class='varid'>scEmpty</span> <span class='layout'>}</span>
<a name="line-151"></a> <span class='keyword'>where</span>
<a name="line-152"></a> <span class='varid'>xpLiftMaybe'</span> <span class='conid'>Nothing</span> <span class='keyglyph'>=</span> <span class='varid'>xpZero</span>
<a name="line-153"></a> <span class='varid'>xpLiftMaybe'</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varid'>x</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>xpLift</span> <span class='varid'>x</span>
<a name="line-154"></a>
<a name="line-155"></a>
<a name="line-156"></a><span class='comment'>-- | pickle\/unpickle combinator for sequence and choice.</span>
<a name="line-157"></a><span class='comment'>--</span>
<a name="line-158"></a><span class='comment'>-- When the first unpickler fails,</span>
<a name="line-159"></a><span class='comment'>-- the second one is taken, else the third one configured with the result from the first</span>
<a name="line-160"></a><span class='comment'>-- is taken. This pickler is a generalisation for 'xpSeq' and 'xpChoice' .</span>
<a name="line-161"></a><span class='comment'>--</span>
<a name="line-162"></a><span class='comment'>-- The schema must be attached later, e.g. in xpPair or other higher level combinators</span>
<a name="line-163"></a>
<a name="line-164"></a><a name="xpCondSeq"></a><span class='definition'>xpCondSeq</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='varid'>a</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span>
<a name="line-165"></a><span class='definition'>xpCondSeq</span> <span class='varid'>pd</span> <span class='varid'>f</span> <span class='varid'>pa</span> <span class='varid'>k</span>
<a name="line-166"></a> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>s</span><span class='layout'>)</span> <span class='keyglyph'>-></span>
<a name="line-167"></a> <span class='keyword'>let</span>
<a name="line-168"></a> <span class='varid'>a</span> <span class='keyglyph'>=</span> <span class='varid'>f</span> <span class='varid'>b</span>
<a name="line-169"></a> <span class='varid'>pb</span> <span class='keyglyph'>=</span> <span class='varid'>k</span> <span class='varid'>a</span>
<a name="line-170"></a> <span class='keyword'>in</span>
<a name="line-171"></a> <span class='varid'>appPickle</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>appPickle</span> <span class='varid'>pb</span> <span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>s</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-172"></a> <span class='layout'>)</span>
<a name="line-173"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='varid'>s</span> <span class='keyglyph'>-></span>
<a name="line-174"></a> <span class='keyword'>let</span>
<a name="line-175"></a> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>s'</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='varid'>appUnPickle</span> <span class='varid'>pa</span> <span class='varid'>s</span>
<a name="line-176"></a> <span class='keyword'>in</span>
<a name="line-177"></a> <span class='keyword'>case</span> <span class='varid'>a</span> <span class='keyword'>of</span>
<a name="line-178"></a> <span class='conid'>Nothing</span> <span class='keyglyph'>-></span> <span class='varid'>appUnPickle</span> <span class='varid'>pd</span> <span class='varid'>s</span>
<a name="line-179"></a> <span class='conid'>Just</span> <span class='varid'>a'</span> <span class='keyglyph'>-></span> <span class='varid'>appUnPickle</span> <span class='layout'>(</span><span class='varid'>k</span> <span class='varid'>a'</span><span class='layout'>)</span> <span class='varid'>s'</span>
<a name="line-180"></a> <span class='layout'>)</span>
<a name="line-181"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>undefined</span>
<a name="line-182"></a> <span class='layout'>}</span>
<a name="line-183"></a>
<a name="line-184"></a>
<a name="line-185"></a><span class='comment'>-- | Combine two picklers sequentially.</span>
<a name="line-186"></a><span class='comment'>--</span>
<a name="line-187"></a><span class='comment'>-- If the first fails during</span>
<a name="line-188"></a><span class='comment'>-- unpickling, the whole unpickler fails</span>
<a name="line-189"></a>
<a name="line-190"></a><a name="xpSeq"></a><span class='definition'>xpSeq</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='varid'>a</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span>
<a name="line-191"></a><span class='definition'>xpSeq</span> <span class='keyglyph'>=</span> <span class='varid'>xpCondSeq</span> <span class='varid'>xpZero</span>
<a name="line-192"></a>
<a name="line-193"></a>
<a name="line-194"></a><span class='comment'>-- | combine tow picklers with a choice</span>
<a name="line-195"></a><span class='comment'>--</span>
<a name="line-196"></a><span class='comment'>-- Run two picklers in sequence like with xpSeq.</span>
<a name="line-197"></a><span class='comment'>-- When during unpickling the first one fails,</span>
<a name="line-198"></a><span class='comment'>-- an alternative pickler (first argument) is applied.</span>
<a name="line-199"></a><span class='comment'>-- This pickler only is used as combinator for unpickling.</span>
<a name="line-200"></a>
<a name="line-201"></a><a name="xpChoice"></a><span class='definition'>xpChoice</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span>
<a name="line-202"></a><span class='definition'>xpChoice</span> <span class='varid'>pb</span> <span class='keyglyph'>=</span> <span class='varid'>xpCondSeq</span> <span class='varid'>pb</span> <span class='varid'>undefined</span>
<a name="line-203"></a>
<a name="line-204"></a>
<a name="line-205"></a><span class='comment'>-- | map value into another domain and apply pickler there</span>
<a name="line-206"></a><span class='comment'>--</span>
<a name="line-207"></a><span class='comment'>-- One of the most often used picklers.</span>
<a name="line-208"></a>
<a name="line-209"></a><a name="xpWrap"></a><span class='definition'>xpWrap</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='varid'>a</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span>
<a name="line-210"></a><span class='definition'>xpWrap</span> <span class='layout'>(</span><span class='varid'>i</span><span class='layout'>,</span> <span class='varid'>j</span><span class='layout'>)</span> <span class='varid'>pa</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>xpSeq</span> <span class='varid'>j</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpLift</span> <span class='varop'>.</span> <span class='varid'>i</span><span class='layout'>)</span><span class='layout'>)</span> <span class='layout'>{</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>theSchema</span> <span class='varid'>pa</span> <span class='layout'>}</span>
<a name="line-211"></a>
<a name="line-212"></a><span class='comment'>-- | like 'xpWrap', but if the inverse mapping is undefined, the unpickler fails</span>
<a name="line-213"></a><span class='comment'>--</span>
<a name="line-214"></a><span class='comment'>-- Map a value into another domain. If the inverse mapping is</span>
<a name="line-215"></a><span class='comment'>-- undefined (Nothing), the unpickler fails</span>
<a name="line-216"></a>
<a name="line-217"></a><a name="xpWrapMaybe"></a><span class='definition'>xpWrapMaybe</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='varid'>a</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span>
<a name="line-218"></a><span class='definition'>xpWrapMaybe</span> <span class='layout'>(</span><span class='varid'>i</span><span class='layout'>,</span> <span class='varid'>j</span><span class='layout'>)</span> <span class='varid'>pa</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>xpSeq</span> <span class='varid'>j</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpLiftMaybe</span> <span class='varop'>.</span> <span class='varid'>i</span><span class='layout'>)</span><span class='layout'>)</span> <span class='layout'>{</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>theSchema</span> <span class='varid'>pa</span> <span class='layout'>}</span>
<a name="line-219"></a>
<a name="line-220"></a><span class='comment'>-- | pickle a pair of values sequentially</span>
<a name="line-221"></a><span class='comment'>--</span>
<a name="line-222"></a><span class='comment'>-- Used for pairs or together with wrap for pickling</span>
<a name="line-223"></a><span class='comment'>-- algebraic data types with two components</span>
<a name="line-224"></a>
<a name="line-225"></a><a name="xpPair"></a><span class='definition'>xpPair</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>)</span>
<a name="line-226"></a><span class='definition'>xpPair</span> <span class='varid'>pa</span> <span class='varid'>pb</span>
<a name="line-227"></a> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='varid'>xpSeq</span> <span class='varid'>fst</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='keyglyph'>\</span> <span class='varid'>a</span> <span class='keyglyph'>-></span>
<a name="line-228"></a> <span class='varid'>xpSeq</span> <span class='varid'>snd</span> <span class='varid'>pb</span> <span class='layout'>(</span><span class='keyglyph'>\</span> <span class='varid'>b</span> <span class='keyglyph'>-></span>
<a name="line-229"></a> <span class='varid'>xpLift</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span><span class='varid'>b</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-230"></a> <span class='layout'>)</span> <span class='layout'>{</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scSeq</span> <span class='layout'>(</span><span class='varid'>theSchema</span> <span class='varid'>pa</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>theSchema</span> <span class='varid'>pb</span><span class='layout'>)</span> <span class='layout'>}</span>
<a name="line-231"></a>
<a name="line-232"></a><span class='comment'>-- | Like 'xpPair' but for triples</span>
<a name="line-233"></a>
<a name="line-234"></a><a name="xpTriple"></a><span class='definition'>xpTriple</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>c</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>)</span>
<a name="line-235"></a><span class='definition'>xpTriple</span> <span class='varid'>pa</span> <span class='varid'>pb</span> <span class='varid'>pc</span>
<a name="line-236"></a> <span class='keyglyph'>=</span> <span class='varid'>xpWrap</span> <span class='layout'>(</span><span class='varid'>toTriple</span><span class='layout'>,</span> <span class='varid'>fromTriple</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pb</span> <span class='varid'>pc</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-237"></a> <span class='keyword'>where</span>
<a name="line-238"></a> <span class='varid'>toTriple</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>)</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span> <span class='layout'>)</span>
<a name="line-239"></a> <span class='varid'>fromTriple</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span> <span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-240"></a>
<a name="line-241"></a><span class='comment'>-- | Like 'xpPair' and 'xpTriple' but for 4-tuples</span>
<a name="line-242"></a>
<a name="line-243"></a><a name="xp4Tuple"></a><span class='definition'>xp4Tuple</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>c</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>d</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>)</span>
<a name="line-244"></a><span class='definition'>xp4Tuple</span> <span class='varid'>pa</span> <span class='varid'>pb</span> <span class='varid'>pc</span> <span class='varid'>pd</span>
<a name="line-245"></a> <span class='keyglyph'>=</span> <span class='varid'>xpWrap</span> <span class='layout'>(</span><span class='varid'>toQuad</span><span class='layout'>,</span> <span class='varid'>fromQuad</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pb</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pc</span> <span class='varid'>pd</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-246"></a> <span class='keyword'>where</span>
<a name="line-247"></a> <span class='varid'>toQuad</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span> <span class='layout'>)</span>
<a name="line-248"></a> <span class='varid'>fromQuad</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span> <span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-249"></a>
<a name="line-250"></a><span class='comment'>-- | Like 'xpPair' and 'xpTriple' but for 5-tuples</span>
<a name="line-251"></a>
<a name="line-252"></a><a name="xp5Tuple"></a><span class='definition'>xp5Tuple</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>c</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>d</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>e</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span><span class='layout'>)</span>
<a name="line-253"></a><span class='definition'>xp5Tuple</span> <span class='varid'>pa</span> <span class='varid'>pb</span> <span class='varid'>pc</span> <span class='varid'>pd</span> <span class='varid'>pe</span>
<a name="line-254"></a> <span class='keyglyph'>=</span> <span class='varid'>xpWrap</span> <span class='layout'>(</span><span class='varid'>toQuint</span><span class='layout'>,</span> <span class='varid'>fromQuint</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pb</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pc</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pd</span> <span class='varid'>pe</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-255"></a> <span class='keyword'>where</span>
<a name="line-256"></a> <span class='varid'>toQuint</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>c</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span> <span class='layout'>)</span>
<a name="line-257"></a> <span class='varid'>fromQuint</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span> <span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>c</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-258"></a>
<a name="line-259"></a><span class='comment'>-- | Like 'xpPair' and 'xpTriple' but for 6-tuples</span>
<a name="line-260"></a>
<a name="line-261"></a><a name="xp6Tuple"></a><span class='definition'>xp6Tuple</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>c</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>d</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>e</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>f</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span><span class='layout'>,</span> <span class='varid'>f</span><span class='layout'>)</span>
<a name="line-262"></a><span class='definition'>xp6Tuple</span> <span class='varid'>pa</span> <span class='varid'>pb</span> <span class='varid'>pc</span> <span class='varid'>pd</span> <span class='varid'>pe</span> <span class='varid'>pf</span>
<a name="line-263"></a> <span class='keyglyph'>=</span> <span class='varid'>xpWrap</span> <span class='layout'>(</span><span class='varid'>toSix</span><span class='layout'>,</span> <span class='varid'>fromSix</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pb</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pc</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pd</span> <span class='layout'>(</span><span class='varid'>xpPair</span> <span class='varid'>pe</span> <span class='varid'>pf</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-264"></a> <span class='keyword'>where</span>
<a name="line-265"></a> <span class='varid'>toSix</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>c</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>d</span><span class='layout'>,</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>e</span><span class='layout'>,</span> <span class='varid'>f</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span><span class='layout'>,</span> <span class='varid'>f</span> <span class='layout'>)</span>
<a name="line-266"></a> <span class='varid'>fromSix</span> <span class='keyglyph'>~</span><span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='varid'>d</span><span class='layout'>,</span> <span class='varid'>e</span><span class='layout'>,</span> <span class='varid'>f</span><span class='layout'>)</span> <span class='keyglyph'>=</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>b</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>c</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>d</span><span class='layout'>,</span> <span class='layout'>(</span><span class='varid'>e</span><span class='layout'>,</span> <span class='varid'>f</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-267"></a>
<a name="line-268"></a><span class='comment'>-- | Pickle a string into an XML text node</span>
<a name="line-269"></a><span class='comment'>--</span>
<a name="line-270"></a><span class='comment'>-- One of the most often used primitive picklers. Attention:</span>
<a name="line-271"></a><span class='comment'>-- For pickling empty strings use 'xpText0'. If the text has a more</span>
<a name="line-272"></a><span class='comment'>-- specific datatype than xsd:string, use 'xpTextDT'</span>
<a name="line-273"></a>
<a name="line-274"></a><a name="xpText"></a><span class='definition'>xpText</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='conid'>String</span>
<a name="line-275"></a><span class='definition'>xpText</span> <span class='keyglyph'>=</span> <span class='varid'>xpTextDT</span> <span class='varid'>scString1</span>
<a name="line-276"></a>
<a name="line-277"></a><span class='comment'>-- | Pickle a string into an XML text node</span>
<a name="line-278"></a><span class='comment'>--</span>
<a name="line-279"></a><span class='comment'>-- Text pickler with a description of the structure of the text</span>
<a name="line-280"></a><span class='comment'>-- by a schema. A schema for a data type can be defined by 'Text.XML.HXT.Arrow.Pickle.Schema.scDT'.</span>
<a name="line-281"></a><span class='comment'>-- In 'Text.XML.HXT.Arrow.Pickle.Schema' there are some more functions for creating</span>
<a name="line-282"></a><span class='comment'>-- simple datatype descriptions.</span>
<a name="line-283"></a>
<a name="line-284"></a><a name="xpTextDT"></a><span class='definition'>xpTextDT</span> <span class='keyglyph'>::</span> <span class='conid'>Schema</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='conid'>String</span>
<a name="line-285"></a><span class='definition'>xpTextDT</span> <span class='varid'>sc</span>
<a name="line-286"></a> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>s</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='varid'>addCont</span> <span class='layout'>(</span><span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>mkText</span> <span class='varid'>s</span><span class='layout'>)</span> <span class='varid'>st</span>
<a name="line-287"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='varid'>st</span> <span class='keyglyph'>-></span> <span class='varid'>fromMaybe</span> <span class='layout'>(</span><span class='conid'>Nothing</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>unpickleString</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-288"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>sc</span>
<a name="line-289"></a> <span class='layout'>}</span>
<a name="line-290"></a> <span class='keyword'>where</span>
<a name="line-291"></a> <span class='varid'>unpickleString</span> <span class='varid'>st</span>
<a name="line-292"></a> <span class='keyglyph'>=</span> <span class='keyword'>do</span>
<a name="line-293"></a> <span class='varid'>t</span> <span class='keyglyph'><-</span> <span class='varid'>getCont</span> <span class='varid'>st</span>
<a name="line-294"></a> <span class='varid'>s</span> <span class='keyglyph'><-</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>getText</span> <span class='varid'>t</span>
<a name="line-295"></a> <span class='varid'>return</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varid'>s</span><span class='layout'>,</span> <span class='varid'>dropCont</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-296"></a>
<a name="line-297"></a><span class='comment'>-- | Pickle a possibly empty string into an XML node.</span>
<a name="line-298"></a><span class='comment'>--</span>
<a name="line-299"></a><span class='comment'>-- Must be used in all places, where empty strings are legal values.</span>
<a name="line-300"></a><span class='comment'>-- If the content of an element can be an empty string, this string disapears</span>
<a name="line-301"></a><span class='comment'>-- during storing the DOM into a document and reparse the document.</span>
<a name="line-302"></a><span class='comment'>-- So the empty text node becomes nothing, and the pickler must deliver an empty string,</span>
<a name="line-303"></a><span class='comment'>-- if there is no text node in the document.</span>
<a name="line-304"></a>
<a name="line-305"></a><a name="xpText0"></a><span class='definition'>xpText0</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='conid'>String</span>
<a name="line-306"></a><span class='definition'>xpText0</span> <span class='keyglyph'>=</span> <span class='varid'>xpText0DT</span> <span class='varid'>scString1</span>
<a name="line-307"></a>
<a name="line-308"></a><span class='comment'>-- | Pickle a possibly empty string with a datatype description into an XML node.</span>
<a name="line-309"></a><span class='comment'>--</span>
<a name="line-310"></a><span class='comment'>-- Like 'xpText0' but with extra Parameter for datatype description as in 'xpTextDT'.</span>
<a name="line-311"></a>
<a name="line-312"></a><a name="xpText0DT"></a><span class='definition'>xpText0DT</span> <span class='keyglyph'>::</span> <span class='conid'>Schema</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='conid'>String</span>
<a name="line-313"></a><span class='definition'>xpText0DT</span> <span class='varid'>sc</span>
<a name="line-314"></a> <span class='keyglyph'>=</span> <span class='varid'>xpWrap</span> <span class='layout'>(</span><span class='varid'>fromMaybe</span> <span class='str'>""</span><span class='layout'>,</span> <span class='varid'>emptyToNothing</span><span class='layout'>)</span> <span class='varop'>$</span> <span class='varid'>xpOption</span> <span class='varop'>$</span> <span class='varid'>xpTextDT</span> <span class='varid'>sc</span>
<a name="line-315"></a> <span class='keyword'>where</span>
<a name="line-316"></a> <span class='varid'>emptyToNothing</span> <span class='str'>""</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-317"></a> <span class='varid'>emptyToNothing</span> <span class='varid'>x</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='varid'>x</span>
<a name="line-318"></a>
<a name="line-319"></a><span class='comment'>-- | Pickle an arbitrary value by applyling show during pickling</span>
<a name="line-320"></a><span class='comment'>-- and read during unpickling.</span>
<a name="line-321"></a><span class='comment'>--</span>
<a name="line-322"></a><span class='comment'>-- Real pickling is then done with 'xpText'.</span>
<a name="line-323"></a><span class='comment'>-- One of the most often used pimitive picklers. Applicable for all</span>
<a name="line-324"></a><span class='comment'>-- types which are instances of @Read@ and @Show@</span>
<a name="line-325"></a>
<a name="line-326"></a><a name="xpPrim"></a><span class='definition'>xpPrim</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='conid'>Read</span> <span class='varid'>a</span><span class='layout'>,</span> <span class='conid'>Show</span> <span class='varid'>a</span><span class='layout'>)</span> <span class='keyglyph'>=></span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-327"></a><span class='definition'>xpPrim</span>
<a name="line-328"></a> <span class='keyglyph'>=</span> <span class='varid'>xpWrapMaybe</span> <span class='layout'>(</span><span class='varid'>readMaybe</span><span class='layout'>,</span> <span class='varid'>show</span><span class='layout'>)</span> <span class='varid'>xpText</span>
<a name="line-329"></a> <span class='keyword'>where</span>
<a name="line-330"></a> <span class='varid'>readMaybe</span> <span class='keyglyph'>::</span> <span class='conid'>Read</span> <span class='varid'>a</span> <span class='keyglyph'>=></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>Maybe</span> <span class='varid'>a</span>
<a name="line-331"></a> <span class='varid'>readMaybe</span> <span class='varid'>str</span>
<a name="line-332"></a> <span class='keyglyph'>=</span> <span class='varid'>val</span> <span class='layout'>(</span><span class='varid'>reads</span> <span class='varid'>str</span><span class='layout'>)</span>
<a name="line-333"></a> <span class='keyword'>where</span>
<a name="line-334"></a> <span class='varid'>val</span> <span class='keyglyph'>[</span><span class='layout'>(</span><span class='varid'>x</span><span class='layout'>,</span><span class='str'>""</span><span class='layout'>)</span><span class='keyglyph'>]</span> <span class='keyglyph'>=</span> <span class='conid'>Just</span> <span class='varid'>x</span>
<a name="line-335"></a> <span class='varid'>val</span> <span class='keyword'>_</span> <span class='keyglyph'>=</span> <span class='conid'>Nothing</span>
<a name="line-336"></a>
<a name="line-337"></a><span class='comment'>-- | Pickle an XmlTree by just adding it</span>
<a name="line-338"></a><span class='comment'>--</span>
<a name="line-339"></a><span class='comment'>-- Usefull for components of type XmlTree in other data structures</span>
<a name="line-340"></a>
<a name="line-341"></a><a name="xpTree"></a><span class='definition'>xpTree</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='conid'>XmlTree</span>
<a name="line-342"></a><span class='definition'>xpTree</span> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>s</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='varid'>addCont</span> <span class='varid'>s</span> <span class='varid'>st</span>
<a name="line-343"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='varid'>st</span> <span class='keyglyph'>-></span> <span class='varid'>fromMaybe</span> <span class='layout'>(</span><span class='conid'>Nothing</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>unpickleTree</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-344"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='conid'>Any</span>
<a name="line-345"></a> <span class='layout'>}</span>
<a name="line-346"></a> <span class='keyword'>where</span>
<a name="line-347"></a> <span class='varid'>unpickleTree</span> <span class='varid'>st</span>
<a name="line-348"></a> <span class='keyglyph'>=</span> <span class='keyword'>do</span>
<a name="line-349"></a> <span class='varid'>t</span> <span class='keyglyph'><-</span> <span class='varid'>getCont</span> <span class='varid'>st</span>
<a name="line-350"></a> <span class='varid'>return</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varid'>t</span><span class='layout'>,</span> <span class='varid'>dropCont</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-351"></a>
<a name="line-352"></a><span class='comment'>-- | Encoding of optional data by ignoring the Nothing case during pickling</span>
<a name="line-353"></a><span class='comment'>-- and relying on failure during unpickling to recompute the Nothing case</span>
<a name="line-354"></a><span class='comment'>--</span>
<a name="line-355"></a><span class='comment'>-- The default pickler for Maybe types</span>
<a name="line-356"></a>
<a name="line-357"></a><a name="xpOption"></a><span class='definition'>xpOption</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='layout'>(</span><span class='conid'>Maybe</span> <span class='varid'>a</span><span class='layout'>)</span>
<a name="line-358"></a><span class='definition'>xpOption</span> <span class='varid'>pa</span>
<a name="line-359"></a> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='keyglyph'>-></span>
<a name="line-360"></a> <span class='keyword'>case</span> <span class='varid'>a</span> <span class='keyword'>of</span>
<a name="line-361"></a> <span class='conid'>Nothing</span> <span class='keyglyph'>-></span> <span class='varid'>st</span>
<a name="line-362"></a> <span class='conid'>Just</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='varid'>appPickle</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>x</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-363"></a> <span class='layout'>)</span>
<a name="line-364"></a>
<a name="line-365"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='varid'>appUnPickle</span> <span class='varop'>$</span>
<a name="line-366"></a> <span class='varid'>xpChoice</span> <span class='layout'>(</span><span class='varid'>xpLift</span> <span class='conid'>Nothing</span><span class='layout'>)</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpLift</span> <span class='varop'>.</span> <span class='conid'>Just</span><span class='layout'>)</span>
<a name="line-367"></a>
<a name="line-368"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scOption</span> <span class='layout'>(</span><span class='varid'>theSchema</span> <span class='varid'>pa</span><span class='layout'>)</span>
<a name="line-369"></a> <span class='layout'>}</span>
<a name="line-370"></a>
<a name="line-371"></a><span class='comment'>-- | Encoding of list values by pickling all list elements sequentially.</span>
<a name="line-372"></a><span class='comment'>--</span>
<a name="line-373"></a><span class='comment'>-- Unpickler relies on failure for detecting the end of the list.</span>
<a name="line-374"></a><span class='comment'>-- The standard pickler for lists. Can also be used in combination with 'xpWrap'</span>
<a name="line-375"></a><span class='comment'>-- for constructing set and map picklers</span>
<a name="line-376"></a>
<a name="line-377"></a><a name="xpList"></a><span class='definition'>xpList</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='keyglyph'>[</span><span class='varid'>a</span><span class='keyglyph'>]</span>
<a name="line-378"></a><span class='definition'>xpList</span> <span class='varid'>pa</span>
<a name="line-379"></a> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='keyglyph'>-></span>
<a name="line-380"></a> <span class='keyword'>case</span> <span class='varid'>a</span> <span class='keyword'>of</span>
<a name="line-381"></a> <span class='conid'>[]</span> <span class='keyglyph'>-></span> <span class='varid'>st</span>
<a name="line-382"></a> <span class='keyword'>_</span><span class='conop'>:</span><span class='keyword'>_</span> <span class='keyglyph'>-></span> <span class='varid'>appPickle</span> <span class='varid'>pc</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-383"></a> <span class='layout'>)</span>
<a name="line-384"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='varid'>appUnPickle</span> <span class='varop'>$</span>
<a name="line-385"></a> <span class='varid'>xpChoice</span> <span class='layout'>(</span><span class='varid'>xpLift</span> <span class='conid'>[]</span><span class='layout'>)</span> <span class='varid'>pa</span>
<a name="line-386"></a> <span class='layout'>(</span><span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span> <span class='varid'>xpSeq</span> <span class='varid'>id</span> <span class='layout'>(</span><span class='varid'>xpList</span> <span class='varid'>pa</span><span class='layout'>)</span> <span class='layout'>(</span><span class='keyglyph'>\</span><span class='varid'>xs</span> <span class='keyglyph'>-></span> <span class='varid'>xpLift</span> <span class='layout'>(</span><span class='varid'>x</span><span class='conop'>:</span><span class='varid'>xs</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-387"></a>
<a name="line-388"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scList</span> <span class='layout'>(</span><span class='varid'>theSchema</span> <span class='varid'>pa</span><span class='layout'>)</span>
<a name="line-389"></a> <span class='layout'>}</span>
<a name="line-390"></a> <span class='keyword'>where</span>
<a name="line-391"></a> <span class='varid'>pc</span> <span class='keyglyph'>=</span> <span class='varid'>xpSeq</span> <span class='varid'>head</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='keyglyph'>\</span> <span class='varid'>x</span> <span class='keyglyph'>-></span>
<a name="line-392"></a> <span class='varid'>xpSeq</span> <span class='varid'>tail</span> <span class='layout'>(</span><span class='varid'>xpList</span> <span class='varid'>pa</span><span class='layout'>)</span> <span class='layout'>(</span><span class='keyglyph'>\</span> <span class='varid'>xs</span> <span class='keyglyph'>-></span>
<a name="line-393"></a> <span class='varid'>xpLift</span> <span class='layout'>(</span><span class='varid'>x</span><span class='conop'>:</span><span class='varid'>xs</span><span class='layout'>)</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-394"></a>
<a name="line-395"></a><span class='comment'>-- | Encoding of a none empty list of values</span>
<a name="line-396"></a><span class='comment'>--</span>
<a name="line-397"></a><span class='comment'>-- Attention: when calling this pickler with an empty list,</span>
<a name="line-398"></a><span class='comment'>-- an internal error \"head of empty list is raised\".</span>
<a name="line-399"></a>
<a name="line-400"></a><a name="xpList1"></a><span class='definition'>xpList1</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='keyglyph'>[</span><span class='varid'>a</span><span class='keyglyph'>]</span>
<a name="line-401"></a><span class='definition'>xpList1</span> <span class='varid'>pa</span>
<a name="line-402"></a> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='varid'>xpWrap</span> <span class='layout'>(</span><span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>x</span><span class='layout'>,</span> <span class='varid'>xs</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='varid'>x</span> <span class='conop'>:</span> <span class='varid'>xs</span>
<a name="line-403"></a> <span class='layout'>,</span><span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>x</span> <span class='conop'>:</span> <span class='varid'>xs</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='layout'>(</span><span class='varid'>x</span><span class='layout'>,</span> <span class='varid'>xs</span><span class='layout'>)</span>
<a name="line-404"></a> <span class='layout'>)</span> <span class='varop'>$</span>
<a name="line-405"></a> <span class='varid'>xpPair</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>xpList</span> <span class='varid'>pa</span><span class='layout'>)</span>
<a name="line-406"></a> <span class='layout'>)</span> <span class='layout'>{</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scList1</span> <span class='layout'>(</span><span class='varid'>theSchema</span> <span class='varid'>pa</span><span class='layout'>)</span> <span class='layout'>}</span>
<a name="line-407"></a>
<a name="line-408"></a><span class='comment'>-- | Pickler for sum data types.</span>
<a name="line-409"></a><span class='comment'>--</span>
<a name="line-410"></a><span class='comment'>-- Every constructor is mapped to an index into the list of picklers.</span>
<a name="line-411"></a><span class='comment'>-- The index is used only during pickling, not during unpickling, there the 1. match is taken</span>
<a name="line-412"></a>
<a name="line-413"></a><a name="xpAlt"></a><span class='definition'>xpAlt</span> <span class='keyglyph'>::</span> <span class='layout'>(</span><span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>Int</span><span class='layout'>)</span> <span class='keyglyph'>-></span> <span class='keyglyph'>[</span><span class='conid'>PU</span> <span class='varid'>a</span><span class='keyglyph'>]</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-414"></a><span class='definition'>xpAlt</span> <span class='varid'>tag</span> <span class='varid'>ps</span>
<a name="line-415"></a> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='keyglyph'>-></span>
<a name="line-416"></a> <span class='keyword'>let</span>
<a name="line-417"></a> <span class='varid'>pa</span> <span class='keyglyph'>=</span> <span class='varid'>ps</span> <span class='varop'>!!</span> <span class='layout'>(</span><span class='varid'>tag</span> <span class='varid'>a</span><span class='layout'>)</span>
<a name="line-418"></a> <span class='keyword'>in</span>
<a name="line-419"></a> <span class='varid'>appPickle</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-420"></a> <span class='layout'>)</span>
<a name="line-421"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='varid'>appUnPickle</span> <span class='varop'>$</span>
<a name="line-422"></a> <span class='layout'>(</span> <span class='keyword'>case</span> <span class='varid'>ps</span> <span class='keyword'>of</span>
<a name="line-423"></a> <span class='conid'>[]</span> <span class='keyglyph'>-></span> <span class='varid'>xpZero</span>
<a name="line-424"></a> <span class='varid'>pa</span><span class='conop'>:</span><span class='varid'>ps1</span> <span class='keyglyph'>-></span> <span class='varid'>xpChoice</span> <span class='layout'>(</span><span class='varid'>xpAlt</span> <span class='varid'>tag</span> <span class='varid'>ps1</span><span class='layout'>)</span> <span class='varid'>pa</span> <span class='varid'>xpLift</span>
<a name="line-425"></a> <span class='layout'>)</span>
<a name="line-426"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scAlts</span> <span class='layout'>(</span><span class='varid'>map</span> <span class='varid'>theSchema</span> <span class='varid'>ps</span><span class='layout'>)</span>
<a name="line-427"></a> <span class='layout'>}</span>
<a name="line-428"></a>
<a name="line-429"></a><span class='comment'>-- | Pickler for wrapping\/unwrapping data into an XML element</span>
<a name="line-430"></a><span class='comment'>--</span>
<a name="line-431"></a><span class='comment'>-- Extra parameter is the element name. THE pickler for constructing</span>
<a name="line-432"></a><span class='comment'>-- nested structures</span>
<a name="line-433"></a>
<a name="line-434"></a><a name="xpElem"></a><span class='definition'>xpElem</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-435"></a><span class='definition'>xpElem</span> <span class='varid'>name</span> <span class='varid'>pa</span>
<a name="line-436"></a> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='keyglyph'>-></span>
<a name="line-437"></a> <span class='keyword'>let</span>
<a name="line-438"></a> <span class='varid'>st'</span> <span class='keyglyph'>=</span> <span class='varid'>appPickle</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>emptySt</span><span class='layout'>)</span>
<a name="line-439"></a> <span class='keyword'>in</span>
<a name="line-440"></a> <span class='varid'>addCont</span> <span class='layout'>(</span><span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>mkElement</span> <span class='layout'>(</span><span class='varid'>mkName</span> <span class='varid'>name</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>attributes</span> <span class='varid'>st'</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>contents</span> <span class='varid'>st'</span><span class='layout'>)</span><span class='layout'>)</span> <span class='varid'>st</span>
<a name="line-441"></a> <span class='layout'>)</span>
<a name="line-442"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='varid'>st</span> <span class='keyglyph'>-></span> <span class='varid'>fromMaybe</span> <span class='layout'>(</span><span class='conid'>Nothing</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>unpickleElement</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-443"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scElem</span> <span class='varid'>name</span> <span class='layout'>(</span><span class='varid'>theSchema</span> <span class='varid'>pa</span><span class='layout'>)</span>
<a name="line-444"></a> <span class='layout'>}</span>
<a name="line-445"></a> <span class='keyword'>where</span>
<a name="line-446"></a> <span class='varid'>unpickleElement</span> <span class='varid'>st</span>
<a name="line-447"></a> <span class='keyglyph'>=</span> <span class='keyword'>do</span>
<a name="line-448"></a> <span class='varid'>t</span> <span class='keyglyph'><-</span> <span class='varid'>getCont</span> <span class='varid'>st</span>
<a name="line-449"></a> <span class='varid'>n</span> <span class='keyglyph'><-</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>getElemName</span> <span class='varid'>t</span>
<a name="line-450"></a> <span class='keyword'>if</span> <span class='varid'>qualifiedName</span> <span class='varid'>n</span> <span class='varop'>/=</span> <span class='varid'>name</span>
<a name="line-451"></a> <span class='keyword'>then</span> <span class='varid'>fail</span> <span class='str'>"element name does not match"</span>
<a name="line-452"></a> <span class='keyword'>else</span> <span class='keyword'>do</span>
<a name="line-453"></a> <span class='keyword'>let</span> <span class='varid'>cs</span> <span class='keyglyph'>=</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>getChildren</span> <span class='varid'>t</span>
<a name="line-454"></a> <span class='varid'>al</span> <span class='keyglyph'><-</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>getAttrl</span> <span class='varid'>t</span>
<a name="line-455"></a> <span class='varid'>res</span> <span class='keyglyph'><-</span> <span class='varid'>fst</span> <span class='varop'>.</span> <span class='varid'>appUnPickle</span> <span class='varid'>pa</span> <span class='varop'>$</span> <span class='conid'>St</span> <span class='layout'>{</span><span class='varid'>attributes</span> <span class='keyglyph'>=</span> <span class='varid'>al</span><span class='layout'>,</span> <span class='varid'>contents</span> <span class='keyglyph'>=</span> <span class='varid'>cs</span><span class='layout'>}</span>
<a name="line-456"></a> <span class='varid'>return</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varid'>res</span><span class='layout'>,</span> <span class='varid'>dropCont</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-457"></a>
<a name="line-458"></a><span class='comment'>-- | Pickler for storing\/retreiving data into\/from an attribute value</span>
<a name="line-459"></a><span class='comment'>--</span>
<a name="line-460"></a><span class='comment'>-- The attribute is inserted in the surrounding element constructed by the 'xpElem' pickler</span>
<a name="line-461"></a>
<a name="line-462"></a><a name="xpAttr"></a><span class='definition'>xpAttr</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-463"></a><span class='definition'>xpAttr</span> <span class='varid'>name</span> <span class='varid'>pa</span>
<a name="line-464"></a> <span class='keyglyph'>=</span> <span class='conid'>PU</span> <span class='layout'>{</span> <span class='varid'>appPickle</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='keyglyph'>-></span>
<a name="line-465"></a> <span class='keyword'>let</span>
<a name="line-466"></a> <span class='varid'>st'</span> <span class='keyglyph'>=</span> <span class='varid'>appPickle</span> <span class='varid'>pa</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span> <span class='varid'>emptySt</span><span class='layout'>)</span>
<a name="line-467"></a> <span class='keyword'>in</span>
<a name="line-468"></a> <span class='varid'>addAtt</span> <span class='layout'>(</span><span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>mkAttr</span> <span class='layout'>(</span><span class='varid'>mkName</span> <span class='varid'>name</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>contents</span> <span class='varid'>st'</span><span class='layout'>)</span><span class='layout'>)</span> <span class='varid'>st</span>
<a name="line-469"></a> <span class='layout'>)</span>
<a name="line-470"></a> <span class='layout'>,</span> <span class='varid'>appUnPickle</span> <span class='keyglyph'>=</span> <span class='keyglyph'>\</span> <span class='varid'>st</span> <span class='keyglyph'>-></span> <span class='varid'>fromMaybe</span> <span class='layout'>(</span><span class='conid'>Nothing</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='layout'>(</span><span class='varid'>unpickleAttr</span> <span class='varid'>st</span><span class='layout'>)</span>
<a name="line-471"></a> <span class='layout'>,</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scAttr</span> <span class='varid'>name</span> <span class='layout'>(</span><span class='varid'>theSchema</span> <span class='varid'>pa</span><span class='layout'>)</span>
<a name="line-472"></a> <span class='layout'>}</span>
<a name="line-473"></a> <span class='keyword'>where</span>
<a name="line-474"></a> <span class='varid'>unpickleAttr</span> <span class='varid'>st</span>
<a name="line-475"></a> <span class='keyglyph'>=</span> <span class='keyword'>do</span>
<a name="line-476"></a> <span class='varid'>a</span> <span class='keyglyph'><-</span> <span class='varid'>getAtt</span> <span class='varid'>name</span> <span class='varid'>st</span>
<a name="line-477"></a> <span class='keyword'>let</span> <span class='varid'>av</span> <span class='keyglyph'>=</span> <span class='conid'>XN</span><span class='varop'>.</span><span class='varid'>getChildren</span> <span class='varid'>a</span>
<a name="line-478"></a> <span class='varid'>res</span> <span class='keyglyph'><-</span> <span class='varid'>fst</span> <span class='varop'>.</span> <span class='varid'>appUnPickle</span> <span class='varid'>pa</span> <span class='varop'>$</span> <span class='conid'>St</span> <span class='layout'>{</span><span class='varid'>attributes</span> <span class='keyglyph'>=</span> <span class='conid'>[]</span><span class='layout'>,</span> <span class='varid'>contents</span> <span class='keyglyph'>=</span> <span class='varid'>av</span><span class='layout'>}</span>
<a name="line-479"></a> <span class='varid'>return</span> <span class='layout'>(</span><span class='conid'>Just</span> <span class='varid'>res</span><span class='layout'>,</span> <span class='varid'>st</span><span class='layout'>)</span> <span class='comment'>-- attribute is not removed from attribute list,</span>
<a name="line-480"></a> <span class='comment'>-- attributes are selected by name</span>
<a name="line-481"></a>
<a name="line-482"></a><span class='comment'>-- | Add an optional attribute for an optional value (Maybe a).</span>
<a name="line-483"></a>
<a name="line-484"></a><a name="xpAttrImplied"></a><span class='definition'>xpAttrImplied</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='layout'>(</span><span class='conid'>Maybe</span> <span class='varid'>a</span><span class='layout'>)</span>
<a name="line-485"></a><span class='definition'>xpAttrImplied</span> <span class='varid'>name</span> <span class='varid'>pa</span>
<a name="line-486"></a> <span class='keyglyph'>=</span> <span class='varid'>xpOption</span> <span class='varop'>$</span> <span class='varid'>xpAttr</span> <span class='varid'>name</span> <span class='varid'>pa</span>
<a name="line-487"></a>
<a name="line-488"></a><a name="xpAttrFixed"></a><span class='definition'>xpAttrFixed</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='conid'>()</span>
<a name="line-489"></a><span class='definition'>xpAttrFixed</span> <span class='varid'>name</span> <span class='varid'>val</span>
<a name="line-490"></a> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='varid'>xpWrapMaybe</span> <span class='layout'>(</span> <span class='keyglyph'>\</span> <span class='varid'>v</span> <span class='keyglyph'>-></span> <span class='keyword'>if</span> <span class='varid'>v</span> <span class='varop'>==</span> <span class='varid'>val</span> <span class='keyword'>then</span> <span class='conid'>Just</span> <span class='conid'>()</span> <span class='keyword'>else</span> <span class='conid'>Nothing</span>
<a name="line-491"></a> <span class='layout'>,</span> <span class='varid'>const</span> <span class='varid'>val</span>
<a name="line-492"></a> <span class='layout'>)</span> <span class='varop'>$</span>
<a name="line-493"></a> <span class='varid'>xpAttr</span> <span class='varid'>name</span> <span class='varid'>xpText</span>
<a name="line-494"></a> <span class='layout'>)</span> <span class='layout'>{</span> <span class='varid'>theSchema</span> <span class='keyglyph'>=</span> <span class='varid'>scAttr</span> <span class='varid'>name</span> <span class='layout'>(</span><span class='varid'>scFixed</span> <span class='varid'>val</span><span class='layout'>)</span> <span class='layout'>}</span>
<a name="line-495"></a>
<a name="line-496"></a><span class='comment'>-- | Add an attribute with a fixed value.</span>
<a name="line-497"></a><span class='comment'>--</span>
<a name="line-498"></a><span class='comment'>-- Useful e.g. to declare namespaces. Is implemented by 'xpAttrFixed'</span>
<a name="line-499"></a>
<a name="line-500"></a><a name="xpAddFixedAttr"></a><span class='definition'>xpAddFixedAttr</span> <span class='keyglyph'>::</span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-501"></a><span class='definition'>xpAddFixedAttr</span> <span class='varid'>name</span> <span class='varid'>val</span> <span class='varid'>pa</span>
<a name="line-502"></a> <span class='keyglyph'>=</span> <span class='varid'>xpWrap</span> <span class='layout'>(</span> <span class='varid'>snd</span>
<a name="line-503"></a> <span class='layout'>,</span> <span class='conid'>(,)</span> <span class='conid'>()</span>
<a name="line-504"></a> <span class='layout'>)</span> <span class='varop'>$</span>
<a name="line-505"></a> <span class='varid'>xpPair</span> <span class='layout'>(</span><span class='varid'>xpAttrFixed</span> <span class='varid'>name</span> <span class='varid'>val</span><span class='layout'>)</span> <span class='varid'>pa</span>
<a name="line-506"></a>
<a name="line-507"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-508"></a>
<a name="line-509"></a><span class='comment'>-- | The class for overloading 'xpickle', the default pickler</span>
<a name="line-510"></a>
<a name="line-511"></a><a name="XmlPickler"></a><span class='keyword'>class</span> <span class='conid'>XmlPickler</span> <span class='varid'>a</span> <span class='keyword'>where</span>
<a name="line-512"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span>
<a name="line-513"></a>
<a name="line-514"></a><span class='keyword'>instance</span> <span class='conid'>XmlPickler</span> <span class='conid'>Int</span> <span class='keyword'>where</span>
<a name="line-515"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xpPrim</span>
<a name="line-516"></a>
<a name="line-517"></a><span class='keyword'>instance</span> <span class='conid'>XmlPickler</span> <span class='conid'>Integer</span> <span class='keyword'>where</span>
<a name="line-518"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xpPrim</span>
<a name="line-519"></a>
<a name="line-520"></a><span class='comment'>{-
<a name="line-521"></a> no instance of XmlPickler Char
<a name="line-522"></a> because then every text would be encoded
<a name="line-523"></a> char by char, because of the instance for lists
<a name="line-524"></a>
<a name="line-525"></a>instance XmlPickler Char where
<a name="line-526"></a> xpickle = xpPrim
<a name="line-527"></a>-}</span>
<a name="line-528"></a>
<a name="line-529"></a><span class='keyword'>instance</span> <span class='conid'>XmlPickler</span> <span class='conid'>()</span> <span class='keyword'>where</span>
<a name="line-530"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xpUnit</span>
<a name="line-531"></a>
<a name="line-532"></a><span class='keyword'>instance</span> <span class='layout'>(</span><span class='conid'>XmlPickler</span> <span class='varid'>a</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>b</span><span class='layout'>)</span> <span class='keyglyph'>=></span> <span class='conid'>XmlPickler</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span><span class='varid'>b</span><span class='layout'>)</span> <span class='keyword'>where</span>
<a name="line-533"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xpPair</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span>
<a name="line-534"></a>
<a name="line-535"></a><span class='keyword'>instance</span> <span class='layout'>(</span><span class='conid'>XmlPickler</span> <span class='varid'>a</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>c</span><span class='layout'>)</span> <span class='keyglyph'>=></span> <span class='conid'>XmlPickler</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span><span class='varid'>b</span><span class='layout'>,</span><span class='varid'>c</span><span class='layout'>)</span> <span class='keyword'>where</span>
<a name="line-536"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xpTriple</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span>
<a name="line-537"></a>
<a name="line-538"></a><span class='keyword'>instance</span> <span class='layout'>(</span><span class='conid'>XmlPickler</span> <span class='varid'>a</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>d</span><span class='layout'>)</span> <span class='keyglyph'>=></span> <span class='conid'>XmlPickler</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span><span class='varid'>b</span><span class='layout'>,</span><span class='varid'>c</span><span class='layout'>,</span><span class='varid'>d</span><span class='layout'>)</span> <span class='keyword'>where</span>
<a name="line-539"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xp4Tuple</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span>
<a name="line-540"></a>
<a name="line-541"></a><span class='keyword'>instance</span> <span class='layout'>(</span><span class='conid'>XmlPickler</span> <span class='varid'>a</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>b</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>c</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>d</span><span class='layout'>,</span> <span class='conid'>XmlPickler</span> <span class='varid'>e</span><span class='layout'>)</span> <span class='keyglyph'>=></span> <span class='conid'>XmlPickler</span> <span class='layout'>(</span><span class='varid'>a</span><span class='layout'>,</span><span class='varid'>b</span><span class='layout'>,</span><span class='varid'>c</span><span class='layout'>,</span><span class='varid'>d</span><span class='layout'>,</span><span class='varid'>e</span><span class='layout'>)</span> <span class='keyword'>where</span>
<a name="line-542"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xp5Tuple</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span> <span class='varid'>xpickle</span>
<a name="line-543"></a>
<a name="line-544"></a><span class='keyword'>instance</span> <span class='conid'>XmlPickler</span> <span class='varid'>a</span> <span class='keyglyph'>=></span> <span class='conid'>XmlPickler</span> <span class='keyglyph'>[</span><span class='varid'>a</span><span class='keyglyph'>]</span> <span class='keyword'>where</span>
<a name="line-545"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xpList</span> <span class='varid'>xpickle</span>
<a name="line-546"></a>
<a name="line-547"></a><span class='keyword'>instance</span> <span class='conid'>XmlPickler</span> <span class='varid'>a</span> <span class='keyglyph'>=></span> <span class='conid'>XmlPickler</span> <span class='layout'>(</span><span class='conid'>Maybe</span> <span class='varid'>a</span><span class='layout'>)</span> <span class='keyword'>where</span>
<a name="line-548"></a> <span class='varid'>xpickle</span> <span class='keyglyph'>=</span> <span class='varid'>xpOption</span> <span class='varid'>xpickle</span>
<a name="line-549"></a>
<a name="line-550"></a><span class='comment'>-- ------------------------------------------------------------</span>
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