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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
<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>
<a name="line-40"></a> <span class='layout'>(</span> <span class='varid'>xpickleDocument</span> <span class='comment'>-- from this module Text.XML.HXT.Arrow.Pickle</span>
<a name="line-41"></a> <span class='layout'>,</span> <span class='varid'>xunpickleDocument</span>
<a name="line-42"></a> <span class='layout'>,</span> <span class='varid'>xpickleWriteDTD</span>
<a name="line-43"></a> <span class='layout'>,</span> <span class='varid'>xpickleDTD</span>
<a name="line-44"></a> <span class='layout'>,</span> <span class='varid'>checkPickler</span>
<a name="line-45"></a> <span class='layout'>,</span> <span class='varid'>xpickleVal</span>
<a name="line-46"></a> <span class='layout'>,</span> <span class='varid'>xunpickleVal</span>
<a name="line-47"></a> <span class='layout'>,</span> <span class='varid'>thePicklerDTD</span>
<a name="line-48"></a> <span class='layout'>,</span> <span class='varid'>a_addDTD</span>
<a name="line-49"></a>
<a name="line-50"></a> <span class='comment'>-- from Text.XML.HXT.Arrow.Pickle.Xml</span>
<a name="line-51"></a> <span class='layout'>,</span> <span class='varid'>pickleDoc</span>
<a name="line-52"></a> <span class='layout'>,</span> <span class='varid'>unpickleDoc</span>
<a name="line-53"></a>
<a name="line-54"></a> <span class='layout'>,</span> <span class='conid'>PU</span><span class='layout'>(</span><span class='keyglyph'>..</span><span class='layout'>)</span>
<a name="line-55"></a> <span class='layout'>,</span> <span class='conid'>XmlPickler</span>
<a name="line-56"></a>
<a name="line-57"></a> <span class='layout'>,</span> <span class='varid'>xp4Tuple</span>
<a name="line-58"></a> <span class='layout'>,</span> <span class='varid'>xp5Tuple</span>
<a name="line-59"></a> <span class='layout'>,</span> <span class='varid'>xpAddFixedAttr</span>
<a name="line-60"></a> <span class='layout'>,</span> <span class='varid'>xpAlt</span>
<a name="line-61"></a> <span class='layout'>,</span> <span class='varid'>xpAttr</span>
<a name="line-62"></a> <span class='layout'>,</span> <span class='varid'>xpAttrFixed</span>
<a name="line-63"></a> <span class='layout'>,</span> <span class='varid'>xpAttrImplied</span>
<a name="line-64"></a> <span class='layout'>,</span> <span class='varid'>xpChoice</span>
<a name="line-65"></a> <span class='layout'>,</span> <span class='varid'>xpCondSeq</span>
<a name="line-66"></a> <span class='layout'>,</span> <span class='varid'>xpElem</span>
<a name="line-67"></a> <span class='layout'>,</span> <span class='varid'>xpickle</span>
<a name="line-68"></a> <span class='layout'>,</span> <span class='varid'>xpLift</span>
<a name="line-69"></a> <span class='layout'>,</span> <span class='varid'>xpLiftMaybe</span>
<a name="line-70"></a> <span class='layout'>,</span> <span class='varid'>xpList</span>
<a name="line-71"></a> <span class='layout'>,</span> <span class='varid'>xpList1</span>
<a name="line-72"></a> <span class='layout'>,</span> <span class='varid'>xpOption</span>
<a name="line-73"></a> <span class='layout'>,</span> <span class='varid'>xpPair</span>
<a name="line-74"></a> <span class='layout'>,</span> <span class='varid'>xpPrim</span>
<a name="line-75"></a> <span class='layout'>,</span> <span class='varid'>xpSeq</span>
<a name="line-76"></a> <span class='layout'>,</span> <span class='varid'>xpText</span>
<a name="line-77"></a> <span class='layout'>,</span> <span class='varid'>xpText0</span>
<a name="line-78"></a> <span class='layout'>,</span> <span class='varid'>xpTextDT</span>
<a name="line-79"></a> <span class='layout'>,</span> <span class='varid'>xpText0DT</span>
<a name="line-80"></a> <span class='layout'>,</span> <span class='varid'>xpTree</span>
<a name="line-81"></a> <span class='layout'>,</span> <span class='varid'>xpTriple</span>
<a name="line-82"></a> <span class='layout'>,</span> <span class='varid'>xpUnit</span>
<a name="line-83"></a> <span class='layout'>,</span> <span class='varid'>xpWrap</span>
<a name="line-84"></a> <span class='layout'>,</span> <span class='varid'>xpWrapMaybe</span>
<a name="line-85"></a> <span class='layout'>,</span> <span class='varid'>xpZero</span>
<a name="line-86"></a>
<a name="line-87"></a> <span class='comment'>-- from Text.XML.HXT.Arrow.Pickle.Schema</span>
<a name="line-88"></a> <span class='layout'>,</span> <span class='conid'>Schema</span>
<a name="line-89"></a> <span class='layout'>,</span> <span class='conid'>Schemas</span>
<a name="line-90"></a> <span class='layout'>,</span> <span class='conid'>DataTypeDescr</span>
<a name="line-91"></a> <span class='layout'>)</span>
<a name="line-92"></a><span class='keyword'>where</span>
<a name="line-93"></a>
<a name="line-94"></a><span class='keyword'>import</span> <span class='conid'>Data</span><span class='varop'>.</span><span class='conid'>Maybe</span>
<a name="line-95"></a>
<a name="line-96"></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-97"></a>
<a name="line-98"></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-99"></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-100"></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'>XmlIOStateArrow</span>
<a name="line-101"></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'>ReadDocument</span>
<a name="line-102"></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'>WriteDocument</span>
<a name="line-103"></a>
<a name="line-104"></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'>Xml</span>
<a name="line-105"></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-106"></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'>DTD</span>
<a name="line-107"></a>
<a name="line-108"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-109"></a>
<a name="line-110"></a><span class='comment'>-- the arrow interface for pickling and unpickling</span>
<a name="line-111"></a>
<a name="line-112"></a><span class='comment'>-- | store an arbitray value in a persistent XML document</span>
<a name="line-113"></a><span class='comment'>--</span>
<a name="line-114"></a><span class='comment'>-- The pickler converts a value into an XML tree, this is written out with</span>
<a name="line-115"></a><span class='comment'>-- 'Text.XML.HXT.Arrow.writeDocument'. The option list is passed to 'Text.XML.HXT.Arrow.writeDocument'</span>
<a name="line-116"></a><span class='comment'>--</span>
<a name="line-117"></a><span class='comment'>-- An option evaluated by this arrow is 'a_addDTD'.</span>
<a name="line-118"></a><span class='comment'>-- If 'a_addDTD' is set ('v_1'), the pickler DTD is added as an inline DTD into the document.</span>
<a name="line-119"></a>
<a name="line-120"></a><a name="xpickleDocument"></a><span class='definition'>xpickleDocument</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>Attributes</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>IOStateArrow</span> <span class='varid'>s</span> <span class='varid'>a</span> <span class='conid'>XmlTree</span>
<a name="line-121"></a><span class='definition'>xpickleDocument</span> <span class='varid'>xp</span> <span class='varid'>al</span> <span class='varid'>dest</span>
<a name="line-122"></a> <span class='keyglyph'>=</span> <span class='varid'>xpickleVal</span> <span class='varid'>xp</span>
<a name="line-123"></a> <span class='varop'>>>></span>
<a name="line-124"></a> <span class='varid'>traceMsg</span> <span class='num'>1</span> <span class='str'>"xpickleVal applied"</span>
<a name="line-125"></a> <span class='varop'>>>></span>
<a name="line-126"></a> <span class='layout'>(</span> <span class='keyword'>if</span> <span class='varid'>lookup1</span> <span class='varid'>a_addDTD</span> <span class='varid'>al</span> <span class='varop'>==</span> <span class='varid'>v_1</span>
<a name="line-127"></a> <span class='keyword'>then</span> <span class='varid'>replaceChildren</span> <span class='layout'>(</span> <span class='layout'>(</span><span class='varid'>constA</span> <span class='varid'>undefined</span> <span class='varop'>>>></span> <span class='varid'>xpickleDTD</span> <span class='varid'>xp</span> <span class='varop'>>>></span> <span class='varid'>getChildren</span><span class='layout'>)</span>
<a name="line-128"></a> <span class='varop'><+></span>
<a name="line-129"></a> <span class='varid'>getChildren</span>
<a name="line-130"></a> <span class='layout'>)</span>
<a name="line-131"></a> <span class='keyword'>else</span> <span class='varid'>this</span>
<a name="line-132"></a> <span class='layout'>)</span>
<a name="line-133"></a> <span class='varop'>>>></span>
<a name="line-134"></a> <span class='varid'>writeDocument</span> <span class='varid'>al</span> <span class='varid'>dest</span>
<a name="line-135"></a>
<a name="line-136"></a><span class='comment'>-- | Option for generating and adding DTD when document is pickled</span>
<a name="line-137"></a>
<a name="line-138"></a><a name="a_addDTD"></a><span class='definition'>a_addDTD</span> <span class='keyglyph'>::</span> <span class='conid'>String</span>
<a name="line-139"></a><span class='definition'>a_addDTD</span> <span class='keyglyph'>=</span> <span class='str'>"addDTD"</span>
<a name="line-140"></a>
<a name="line-141"></a><span class='comment'>-- | read an arbitray value from an XML document</span>
<a name="line-142"></a><span class='comment'>--</span>
<a name="line-143"></a><span class='comment'>-- The document is read with 'Text.XML.HXT.Arrow.readDocument'. Options are passed</span>
<a name="line-144"></a><span class='comment'>-- to 'Text.XML.HXT.Arrow.readDocument'. The conversion from XmlTree is done with the</span>
<a name="line-145"></a><span class='comment'>-- pickler.</span>
<a name="line-146"></a><span class='comment'>--</span>
<a name="line-147"></a><span class='comment'>-- @ xpickleDocument xp al dest >>> xunpickleDocument xp al' dest @ is the identity arrow</span>
<a name="line-148"></a><span class='comment'>-- when applied with the appropriate options. When during pickling indentation is switched on,</span>
<a name="line-149"></a><span class='comment'>-- the whitespace must be removed during unpickling.</span>
<a name="line-150"></a>
<a name="line-151"></a><a name="xunpickleDocument"></a><span class='definition'>xunpickleDocument</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>Attributes</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>IOStateArrow</span> <span class='varid'>s</span> <span class='varid'>b</span> <span class='varid'>a</span>
<a name="line-152"></a><span class='definition'>xunpickleDocument</span> <span class='varid'>xp</span> <span class='varid'>al</span> <span class='varid'>src</span>
<a name="line-153"></a> <span class='keyglyph'>=</span> <span class='varid'>readDocument</span> <span class='varid'>al</span> <span class='varid'>src</span>
<a name="line-154"></a> <span class='varop'>>>></span>
<a name="line-155"></a> <span class='varid'>traceMsg</span> <span class='num'>1</span> <span class='layout'>(</span><span class='str'>"xunpickleVal for "</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>src</span> <span class='varop'>++</span> <span class='str'>" started"</span><span class='layout'>)</span>
<a name="line-156"></a> <span class='varop'>>>></span>
<a name="line-157"></a> <span class='varid'>xunpickleVal</span> <span class='varid'>xp</span>
<a name="line-158"></a> <span class='varop'>>>></span>
<a name="line-159"></a> <span class='varid'>traceMsg</span> <span class='num'>1</span> <span class='layout'>(</span><span class='str'>"xunpickleVal for "</span> <span class='varop'>++</span> <span class='varid'>show</span> <span class='varid'>src</span> <span class='varop'>++</span> <span class='str'>" finished"</span><span class='layout'>)</span>
<a name="line-160"></a>
<a name="line-161"></a><span class='comment'>-- | Write out the DTD generated out of a pickler. Calls 'xpicklerDTD'</span>
<a name="line-162"></a>
<a name="line-163"></a><a name="xpickleWriteDTD"></a><span class='definition'>xpickleWriteDTD</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>Attributes</span> <span class='keyglyph'>-></span> <span class='conid'>String</span> <span class='keyglyph'>-></span> <span class='conid'>IOStateArrow</span> <span class='varid'>s</span> <span class='varid'>b</span> <span class='conid'>XmlTree</span>
<a name="line-164"></a><span class='definition'>xpickleWriteDTD</span> <span class='varid'>xp</span> <span class='varid'>al</span> <span class='varid'>dest</span>
<a name="line-165"></a> <span class='keyglyph'>=</span> <span class='varid'>xpickleDTD</span> <span class='varid'>xp</span>
<a name="line-166"></a> <span class='varop'>>>></span>
<a name="line-167"></a> <span class='varid'>writeDocument</span> <span class='varid'>al</span> <span class='varid'>dest</span>
<a name="line-168"></a>
<a name="line-169"></a><span class='comment'>-- | The arrow for generating the DTD out of a pickler</span>
<a name="line-170"></a><span class='comment'>--</span>
<a name="line-171"></a><span class='comment'>-- A DTD is generated from a pickler and check for consistency.</span>
<a name="line-172"></a><span class='comment'>-- Errors concerning the DTD are issued.</span>
<a name="line-173"></a>
<a name="line-174"></a><a name="xpickleDTD"></a><span class='definition'>xpickleDTD</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>IOStateArrow</span> <span class='varid'>s</span> <span class='varid'>b</span> <span class='conid'>XmlTree</span>
<a name="line-175"></a><span class='definition'>xpickleDTD</span> <span class='varid'>xp</span> <span class='keyglyph'>=</span> <span class='varid'>root</span> <span class='conid'>[]</span> <span class='keyglyph'>[</span> <span class='varid'>constL</span> <span class='layout'>(</span><span class='varid'>thePicklerDTD</span> <span class='varid'>xp</span><span class='layout'>)</span>
<a name="line-176"></a> <span class='varop'>>>></span>
<a name="line-177"></a> <span class='varid'>filterErrorMsg</span>
<a name="line-178"></a> <span class='keyglyph'>]</span>
<a name="line-179"></a>
<a name="line-180"></a><span class='comment'>-- | An arrow for checking picklers</span>
<a name="line-181"></a><span class='comment'>--</span>
<a name="line-182"></a><span class='comment'>-- A value is transformed into an XML document by a given pickler,</span>
<a name="line-183"></a><span class='comment'>-- the associated DTD is extracted from the pickler and checked,</span>
<a name="line-184"></a><span class='comment'>-- the document including the DTD is tranlated into a string,</span>
<a name="line-185"></a><span class='comment'>-- this string is read and validated against the included DTD,</span>
<a name="line-186"></a><span class='comment'>-- and unpickled.</span>
<a name="line-187"></a><span class='comment'>-- The last step is the equality with the input.</span>
<a name="line-188"></a><span class='comment'>--</span>
<a name="line-189"></a><span class='comment'>-- If the check succeeds, the arrow works like this, else it fails.</span>
<a name="line-190"></a>
<a name="line-191"></a><a name="checkPickler"></a><span class='definition'>checkPickler</span> <span class='keyglyph'>::</span> <span class='conid'>Eq</span> <span class='varid'>a</span> <span class='keyglyph'>=></span> <span class='conid'>PU</span> <span class='varid'>a</span> <span class='keyglyph'>-></span> <span class='conid'>IOStateArrow</span> <span class='varid'>s</span> <span class='varid'>a</span> <span class='varid'>a</span>
<a name="line-192"></a><span class='definition'>checkPickler</span> <span class='varid'>xp</span> <span class='keyglyph'>=</span> <span class='layout'>(</span> <span class='layout'>(</span> <span class='layout'>(</span> <span class='layout'>(</span> <span class='varid'>xpickleVal</span> <span class='varid'>xp</span>
<a name="line-193"></a> <span class='varop'>>>></span>
<a name="line-194"></a> <span class='varid'>replaceChildren</span> <span class='layout'>(</span> <span class='layout'>(</span><span class='varid'>constA</span> <span class='varid'>undefined</span> <span class='varop'>>>></span> <span class='varid'>xpickleDTD</span> <span class='varid'>xp</span> <span class='varop'>>>></span> <span class='varid'>getChildren</span><span class='layout'>)</span>
<a name="line-195"></a> <span class='varop'><+></span>
<a name="line-196"></a> <span class='varid'>getChildren</span>
<a name="line-197"></a> <span class='layout'>)</span>
<a name="line-198"></a> <span class='varop'>>>></span>
<a name="line-199"></a> <span class='varid'>writeDocumentToString</span> <span class='conid'>[]</span>
<a name="line-200"></a> <span class='varop'>>>></span>
<a name="line-201"></a> <span class='varid'>readFromString</span> <span class='keyglyph'>[</span><span class='layout'>(</span><span class='varid'>a_validate</span><span class='layout'>,</span> <span class='varid'>v_1</span><span class='layout'>)</span><span class='keyglyph'>]</span>
<a name="line-202"></a> <span class='varop'>>>></span>
<a name="line-203"></a> <span class='layout'>(</span> <span class='varid'>xunpickleVal</span> <span class='varid'>xp</span>
<a name="line-204"></a> <span class='varop'>`orElse`</span>
<a name="line-205"></a> <span class='layout'>(</span> <span class='varid'>issueErr</span> <span class='str'>"unpickling the document failed"</span>
<a name="line-206"></a> <span class='varop'>>>></span>
<a name="line-207"></a> <span class='varid'>none</span>
<a name="line-208"></a> <span class='layout'>)</span>
<a name="line-209"></a> <span class='layout'>)</span>
<a name="line-210"></a> <span class='layout'>)</span>
<a name="line-211"></a> <span class='varop'>&&&</span>
<a name="line-212"></a> <span class='varid'>this</span>
<a name="line-213"></a> <span class='layout'>)</span>
<a name="line-214"></a> <span class='varop'>>>></span> <span class='varid'>isA</span> <span class='layout'>(</span><span class='varid'>uncurry</span> <span class='layout'>(</span><span class='varop'>==</span><span class='layout'>)</span><span class='layout'>)</span>
<a name="line-215"></a> <span class='layout'>)</span>
<a name="line-216"></a> <span class='varop'>`guards`</span> <span class='varid'>this</span>
<a name="line-217"></a> <span class='layout'>)</span>
<a name="line-218"></a> <span class='varop'>`orElse`</span> <span class='varid'>issueErr</span> <span class='str'>"pickle/unpickle combinators failed"</span>
<a name="line-219"></a>
<a name="line-220"></a><span class='comment'>-- | The arrow version of the pickler function</span>
<a name="line-221"></a>
<a name="line-222"></a><a name="xpickleVal"></a><span class='definition'>xpickleVal</span> <span class='keyglyph'>::</span> <span class='conid'>ArrowXml</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='varid'>a</span> <span class='varid'>b</span> <span class='conid'>XmlTree</span>
<a name="line-223"></a><span class='definition'>xpickleVal</span> <span class='varid'>xp</span> <span class='keyglyph'>=</span> <span class='varid'>arr</span> <span class='layout'>(</span><span class='varid'>pickleDoc</span> <span class='varid'>xp</span><span class='layout'>)</span>
<a name="line-224"></a>
<a name="line-225"></a><span class='comment'>-- | The arrow version of the unpickler function</span>
<a name="line-226"></a>
<a name="line-227"></a><a name="xunpickleVal"></a><span class='definition'>xunpickleVal</span> <span class='keyglyph'>::</span> <span class='conid'>ArrowXml</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='varid'>a</span> <span class='conid'>XmlTree</span> <span class='varid'>b</span>
<a name="line-228"></a><span class='definition'>xunpickleVal</span> <span class='varid'>xp</span> <span class='keyglyph'>=</span> <span class='varid'>arrL</span> <span class='layout'>(</span><span class='varid'>maybeToList</span> <span class='varop'>.</span> <span class='varid'>unpickleDoc</span> <span class='varid'>xp</span><span class='layout'>)</span>
<a name="line-229"></a>
<a name="line-230"></a>
<a name="line-231"></a><span class='comment'>-- | Compute the associated DTD of a pickler</span>
<a name="line-232"></a>
<a name="line-233"></a><a name="thePicklerDTD"></a><span class='definition'>thePicklerDTD</span> <span class='keyglyph'>::</span> <span class='conid'>PU</span> <span class='varid'>b</span> <span class='keyglyph'>-></span> <span class='conid'>XmlTrees</span>
<a name="line-234"></a><span class='definition'>thePicklerDTD</span> <span class='keyglyph'>=</span> <span class='varid'>dtdDescrToXml</span> <span class='varop'>.</span> <span class='varid'>dtdDescr</span> <span class='varop'>.</span> <span class='varid'>theSchema</span>
<a name="line-235"></a>
<a name="line-236"></a><span class='comment'>-- ------------------------------------------------------------</span>
<a name="line-237"></a>
<a name="line-238"></a>
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