Sophie

Sophie

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haskell-hxt-8.3.2-1mdv2010.1.x86_64.rpm

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>Text.XML.HXT.Arrow.Pickle</TITLE
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>hxt-8.3.2: A collection of tools for processing XML with Haskell.</TD
><TD CLASS="topbut"
><A HREF="index.html"
>Contents</A
></TD
><TD CLASS="topbut"
><A HREF="doc-index.html"
>Index</A
></TD
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><TD CLASS="modulebar"
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><FONT SIZE="6"
>Text.XML.HXT.Arrow.Pickle</FONT
></TD
><TD ALIGN="right"
><TABLE CLASS="narrow" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="infohead"
>Portability</TD
><TD CLASS="infoval"
>portable</TD
></TR
><TR
><TD CLASS="infohead"
>Stability</TD
><TD CLASS="infoval"
>experimental</TD
></TR
><TR
><TD CLASS="infohead"
>Maintainer</TD
><TD CLASS="infoval"
>Uwe Schmidt (uwe@fh-wedel.de)</TD
></TR
></TABLE
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
>Description</TD
></TR
><TR
><TD CLASS="doc"
><P
>Version    : $Id$
</P
><P
>Pickler functions for converting between user defined data types
and XmlTree data. Usefull for persistent storage and retreival
of arbitray data as XML documents
</P
><P
>This module is an adaptation of the pickler combinators
developed by Andrew Kennedy
( http://research.microsoft.com/~akenn/fun/picklercombinators.pdf )
</P
><P
>The difference to Kennedys approach is that the target is not
a list of Chars but a list of XmlTrees. The basic picklers will
convert data into XML text nodes. New are the picklers for
creating elements and attributes.
</P
><P
>One extension was neccessary: The unpickling may fail.
Therefore the unpickler has a Maybe result type.
Failure is used to unpickle optional elements
(Maybe data) and lists of arbitray length
</P
><P
>There is an example program demonstrating the use
of the picklers for a none trivial data structure.
(see &quot;examples/arrows/pickle&quot; directory)
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
>Synopsis</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpickleDocument"
>xpickleDocument</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AAttributes"
>Attributes</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s a <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxunpickleDocument"
>xunpickleDocument</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AAttributes"
>Attributes</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s b a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpickleWriteDTD"
>xpickleWriteDTD</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AAttributes"
>Attributes</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s b <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpickleDTD"
>xpickleDTD</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s b <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AcheckPickler"
>checkPickler</A
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Eq.html#t%3AEq"
>Eq</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s a a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpickleVal"
>xpickleVal</A
> :: <A HREF="Text-XML-HXT-Arrow-XmlArrow.html#t%3AArrowXml"
>ArrowXml</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; a b <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxunpickleVal"
>xunpickleVal</A
> :: <A HREF="Text-XML-HXT-Arrow-XmlArrow.html#t%3AArrowXml"
>ArrowXml</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; a <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
> b</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AthePicklerDTD"
>thePicklerDTD</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTrees"
>XmlTrees</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3Aa_addDTD"
>a_addDTD</A
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3ApickleDoc"
>pickleDoc</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AunpickleDoc"
>unpickleDoc</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>data</SPAN
>  <A HREF="#t%3APU"
>PU</A
> a = <A HREF="#v%3APU"
>PU</A
> {<TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="recfield"
><A HREF="#v%3AappPickle"
>appPickle</A
> :: (a, <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
>) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
></TD
></TR
><TR
><TD CLASS="recfield"
><A HREF="#v%3AappUnPickle"
>appUnPickle</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
> -&gt; (<A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a, <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
>)</TD
></TR
><TR
><TD CLASS="recfield"
><A HREF="#v%3AtheSchema"
>theSchema</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
></TD
></TR
></TABLE
>}</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>class</SPAN
>  <A HREF="#t%3AXmlPickler"
>XmlPickler</A
> a  <SPAN CLASS="keyword"
>where</SPAN
></TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="#v%3Axpickle"
>xpickle</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3Axp4Tuple"
>xp4Tuple</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> d -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c, d)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3Axp5Tuple"
>xp5Tuple</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> d -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> e -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c, d, e)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3Axp6Tuple"
>xp6Tuple</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> d -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> e -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> f -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c, d, e, f)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpAddFixedAttr"
>xpAddFixedAttr</A
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpAlt"
>xpAlt</A
> ::  (a -&gt; <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Types.html#t%3AInt"
>Int</A
>) -&gt; [<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a] -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpAttr"
>xpAttr</A
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpAttrFixed"
>xpAttrFixed</A
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpAttrImplied"
>xpAttrImplied</A
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (<A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpChoice"
>xpChoice</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; (a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpCondSeq"
>xpCondSeq</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; (b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; (a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpDefault"
>xpDefault</A
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Eq.html#t%3AEq"
>Eq</A
> a =&gt; a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpElem"
>xpElem</A
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpElemWithAttrValue"
>xpElemWithAttrValue</A
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpLift"
>xpLift</A
> ::  a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpLiftMaybe"
>xpLiftMaybe</A
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpList"
>xpList</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> [a]</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpList1"
>xpList1</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> [a]</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpMap"
>xpMap</A
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Ord.html#t%3AOrd"
>Ord</A
> k =&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> k -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> v -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (<A HREF="/usr/share/doc/ghc/libraries/containers/Data-Map.html#t%3AMap"
>Map</A
> k v)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpOption"
>xpOption</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (<A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpPair"
>xpPair</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpPrim"
>xpPrim</A
> :: (<A HREF="/usr/share/doc/ghc/libraries/base/Text-Read.html#t%3ARead"
>Read</A
> a, <A HREF="/usr/share/doc/ghc/libraries/base/Text-Show.html#t%3AShow"
>Show</A
> a) =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpSeq"
>xpSeq</A
> ::  (b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; (a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpText"
>xpText</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpText0"
>xpText0</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpTextDT"
>xpTextDT</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpText0DT"
>xpText0DT</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpTree"
>xpTree</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpTrees"
>xpTrees</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> [<A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
>]</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpTriple"
>xpTriple</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c)</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpUnit"
>xpUnit</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpWrap"
>xpWrap</A
> ::  (a -&gt; b, b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpWrapMaybe"
>xpWrapMaybe</A
> ::  (a -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> b, b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpXmlText"
>xpXmlText</A
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AxpZero"
>xpZero</A
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>data</SPAN
>  <A HREF="#t%3ASchema"
>Schema</A
> </TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>type</SPAN
> <A HREF="#t%3ASchemas"
>Schemas</A
> = [<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
>]</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>data</SPAN
>  <A HREF="#t%3ADataTypeDescr"
>DataTypeDescr</A
> </TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="section1"
>Documentation</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpickleDocument"
><A NAME="v%3AxpickleDocument"
></A
></A
><B
>xpickleDocument</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AAttributes"
>Attributes</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s a <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>store an arbitray value in a persistent XML document
</P
><P
>The pickler converts a value into an XML tree, this is written out with
 Text.XML.HXT.Arrow.writeDocument. The option list is passed to Text.XML.HXT.Arrow.writeDocument
</P
><P
>An option evaluated by this arrow is <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3Aa_addDTD"
>a_addDTD</A
></TT
>.
 If <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3Aa_addDTD"
>a_addDTD</A
></TT
> is set (<TT
><A HREF="Text-XML-HXT-DOM-XmlKeywords.html#v%3Av_1"
>v_1</A
></TT
>), the pickler DTD is added as an inline DTD into the document.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xunpickleDocument"
><A NAME="v%3AxunpickleDocument"
></A
></A
><B
>xunpickleDocument</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AAttributes"
>Attributes</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s b a</TD
></TR
><TR
><TD CLASS="doc"
><P
>read an arbitray value from an XML document
</P
><P
>The document is read with Text.XML.HXT.Arrow.readDocument. Options are passed
 to Text.XML.HXT.Arrow.readDocument. The conversion from XmlTree is done with the
 pickler.
</P
><P
><TT
> xpickleDocument xp al dest &gt;&gt;&gt; xunpickleDocument xp al' dest </TT
> is the identity arrow
 when applied with the appropriate options. When during pickling indentation is switched on,
 the whitespace must be removed during unpickling.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpickleWriteDTD"
><A NAME="v%3AxpickleWriteDTD"
></A
></A
><B
>xpickleWriteDTD</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AAttributes"
>Attributes</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s b <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="doc"
>Write out the DTD generated out of a pickler. Calls xpicklerDTD
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpickleDTD"
><A NAME="v%3AxpickleDTD"
></A
></A
><B
>xpickleDTD</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s b <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>The arrow for generating the DTD out of a pickler
</P
><P
>A DTD is generated from a pickler and check for consistency.
 Errors concerning the DTD are issued.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:checkPickler"
><A NAME="v%3AcheckPickler"
></A
></A
><B
>checkPickler</B
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Eq.html#t%3AEq"
>Eq</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-XmlIOStateArrow.html#t%3AIOStateArrow"
>IOStateArrow</A
> s a a</TD
></TR
><TR
><TD CLASS="doc"
><P
>An arrow for checking picklers
</P
><P
>A value is transformed into an XML document by a given pickler,
 the associated DTD is extracted from the pickler and checked,
 the document including the DTD is tranlated into a string,
 this string is read and validated against the included DTD,
 and unpickled.
 The last step is the equality with the input.
</P
><P
>If the check succeeds, the arrow works like this, else it fails.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpickleVal"
><A NAME="v%3AxpickleVal"
></A
></A
><B
>xpickleVal</B
> :: <A HREF="Text-XML-HXT-Arrow-XmlArrow.html#t%3AArrowXml"
>ArrowXml</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; a b <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="doc"
>The arrow version of the pickler function
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xunpickleVal"
><A NAME="v%3AxunpickleVal"
></A
></A
><B
>xunpickleVal</B
> :: <A HREF="Text-XML-HXT-Arrow-XmlArrow.html#t%3AArrowXml"
>ArrowXml</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; a <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
> b</TD
></TR
><TR
><TD CLASS="doc"
>The arrow version of the unpickler function
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:thePicklerDTD"
><A NAME="v%3AthePicklerDTD"
></A
></A
><B
>thePicklerDTD</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTrees"
>XmlTrees</A
></TD
></TR
><TR
><TD CLASS="doc"
>Compute the associated DTD of a pickler
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:a_addDTD"
><A NAME="v%3Aa_addDTD"
></A
></A
><B
>a_addDTD</B
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="doc"
>Option for generating and adding DTD when document is pickled
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:pickleDoc"
><A NAME="v%3ApickleDoc"
></A
></A
><B
>pickleDoc</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>conversion of an arbitrary value into an XML document tree.
</P
><P
>The pickler, first parameter, controls the conversion process.
 Result is a complete document tree including a root node
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:unpickleDoc"
><A NAME="v%3AunpickleDoc"
></A
></A
><B
>unpickleDoc</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Conversion of an XML document tree into an arbitrary data type
</P
><P
>The inverse of <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3ApickleDoc"
>pickleDoc</A
></TT
>.
 This law should hold for all picklers: <TT
> unpickle px . pickle px $ v == Just v </TT
>.
 Not every possible combination of picklers make sense.
 For reconverting a value from an XML tree, is becomes neccessary,
 to introduce &quot;enough&quot; markup for unpickling the value
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>data</SPAN
>  <A NAME="t:PU"
><A NAME="t%3APU"
></A
></A
><B
>PU</B
> a </TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="section4"
>Constructors</TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="5" CELLPADDING="0"
><TR
><TD CLASS="arg"
><A NAME="v:PU"
><A NAME="v%3APU"
></A
></A
><B
>PU</B
></TD
><TD CLASS="rdoc"
></TD
></TR
><TR
><TD CLASS="body" COLSPAN="2"
><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0"
><TR
><TD CLASS="arg"
><A NAME="v:appPickle"
><A NAME="v%3AappPickle"
></A
></A
><B
>appPickle</B
> :: (a, <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
>) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
></TD
><TD CLASS="rdoc"
></TD
></TR
><TR
><TD CLASS="arg"
><A NAME="v:appUnPickle"
><A NAME="v%3AappUnPickle"
></A
></A
><B
>appUnPickle</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
> -&gt; (<A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a, <A HREF="Text-XML-HXT-Arrow-Pickle-Xml.html#t%3ASt"
>St</A
>)</TD
><TD CLASS="rdoc"
></TD
></TR
><TR
><TD CLASS="arg"
><A NAME="v:theSchema"
><A NAME="v%3AtheSchema"
></A
></A
><B
>theSchema</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
></TD
><TD CLASS="rdoc"
></TD
></TR
></TABLE
></TD
></TR
></TABLE
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>class</SPAN
>  <A NAME="t:XmlPickler"
><A NAME="t%3AXmlPickler"
></A
></A
><B
>XmlPickler</B
> a  <SPAN CLASS="keyword"
>where</SPAN
></TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="ndoc"
>The class for overloading <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3Axpickle"
>xpickle</A
></TT
>, the default pickler
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="section4"
>Methods</TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A NAME="v:xpickle"
><A NAME="v%3Axpickle"
></A
></A
><B
>xpickle</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="section4"
><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:XmlPickler')" ALT="show/hide"
> Instances</TD
></TR
><TR
><TD CLASS="body"
><DIV ID="i:XmlPickler" STYLE="display:block;"
><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Types.html#t%3AInt"
>Int</A
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> <A HREF="/usr/share/doc/ghc/libraries/integer/GHC-Integer.html#t%3AInteger"
>Integer</A
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> ([] a)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> a =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> (<A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a)</TD
></TR
><TR
><TD CLASS="decl"
>(<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> a, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> b) =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> (<A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Tuple.html#t%3A%28%2C%29"
>(,)</A
> a b)</TD
></TR
><TR
><TD CLASS="decl"
>(<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> a, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> b, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> c) =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> (<A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Tuple.html#t%3A%28%2C%2C%29"
>(,,)</A
> a b c)</TD
></TR
><TR
><TD CLASS="decl"
>(<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> a, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> b, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> c, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> d) =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> (<A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Tuple.html#t%3A%28%2C%2C%2C%29"
>(,,,)</A
> a b c d)</TD
></TR
><TR
><TD CLASS="decl"
>(<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> a, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> b, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> c, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> d, <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> e) =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3AXmlPickler"
>XmlPickler</A
> (<A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Tuple.html#t%3A%28%2C%2C%2C%2C%29"
>(,,,,)</A
> a b c d e)</TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xp4Tuple"
><A NAME="v%3Axp4Tuple"
></A
></A
><B
>xp4Tuple</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> d -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c, d)</TD
></TR
><TR
><TD CLASS="doc"
>Like <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpPair"
>xpPair</A
></TT
> and <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpTriple"
>xpTriple</A
></TT
> but for 4-tuples
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xp5Tuple"
><A NAME="v%3Axp5Tuple"
></A
></A
><B
>xp5Tuple</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> d -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> e -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c, d, e)</TD
></TR
><TR
><TD CLASS="doc"
>Like <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpPair"
>xpPair</A
></TT
> and <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpTriple"
>xpTriple</A
></TT
> but for 5-tuples
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xp6Tuple"
><A NAME="v%3Axp6Tuple"
></A
></A
><B
>xp6Tuple</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> d -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> e -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> f -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c, d, e, f)</TD
></TR
><TR
><TD CLASS="doc"
>Like <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpPair"
>xpPair</A
></TT
> and <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpTriple"
>xpTriple</A
></TT
> but for 6-tuples
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpAddFixedAttr"
><A NAME="v%3AxpAddFixedAttr"
></A
></A
><B
>xpAddFixedAttr</B
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Add an attribute with a fixed value.
</P
><P
>Useful e.g. to declare namespaces. Is implemented by <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpAttrFixed"
>xpAttrFixed</A
></TT
>
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpAlt"
><A NAME="v%3AxpAlt"
></A
></A
><B
>xpAlt</B
> ::  (a -&gt; <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Types.html#t%3AInt"
>Int</A
>) -&gt; [<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a] -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickler for sum data types.
</P
><P
>Every constructor is mapped to an index into the list of picklers.
 The index is used only during pickling, not during unpickling, there the 1. match is taken
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpAttr"
><A NAME="v%3AxpAttr"
></A
></A
><B
>xpAttr</B
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>convenient Pickler for xpAttrQN
</P
><PRE
> xpAttr n = xpAttrQN (mkName n)
</PRE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpAttrFixed"
><A NAME="v%3AxpAttrFixed"
></A
></A
><B
>xpAttrFixed</B
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpAttrImplied"
><A NAME="v%3AxpAttrImplied"
></A
></A
><B
>xpAttrImplied</B
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (<A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a)</TD
></TR
><TR
><TD CLASS="doc"
>Add an optional attribute for an optional value (Maybe a).
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpChoice"
><A NAME="v%3AxpChoice"
></A
></A
><B
>xpChoice</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; (a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="doc"
><P
>combine tow picklers with a choice
</P
><P
>Run two picklers in sequence like with xpSeq.
 When during unpickling the first one fails,
 an alternative pickler (first argument) is applied.
 This pickler is only used as combinator for unpickling.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpCondSeq"
><A NAME="v%3AxpCondSeq"
></A
></A
><B
>xpCondSeq</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; (b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; (a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="doc"
><P
>pickle/unpickle combinator for sequence and choice.
</P
><P
>When the first unpickler fails,
 the second one is taken, else the third one configured with the result from the first
 is taken. This pickler is a generalisation for <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpSeq"
>xpSeq</A
></TT
> and <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpChoice"
>xpChoice</A
></TT
> .
</P
><P
>The schema must be attached later, e.g. in xpPair or other higher level combinators
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpDefault"
><A NAME="v%3AxpDefault"
></A
></A
><B
>xpDefault</B
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Eq.html#t%3AEq"
>Eq</A
> a =&gt; a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Optional conversion with default value
</P
><P
>The default value is not encoded in the XML document,
 during unpickling the default value is inserted if the pickler fails
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpElem"
><A NAME="v%3AxpElem"
></A
></A
><B
>xpElem</B
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>convenient Pickler for xpElemQN
</P
><PRE
> xpElem n = xpElemQN (mkName n)
</PRE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpElemWithAttrValue"
><A NAME="v%3AxpElemWithAttrValue"
></A
></A
><B
>xpElemWithAttrValue</B
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickler for wrapping/unwrapping data into an XML element with an attribute with given value
</P
><P
>To make XML structures flexible but limit the number of different elements, it's sometimes
 useful to use a kind of generic element with a key value structure
</P
><P
>Example:
</P
><PRE
> &lt;attr name=&quot;key1&quot;&gt;value1&lt;/attr&gt;
 &lt;attr name=&quot;key2&quot;&gt;value2&lt;/attr&gt;
 &lt;attr name=&quot;key3&quot;&gt;value3&lt;/attr&gt;
</PRE
><P
>the Haskell datatype may look like this
</P
><PRE
> type T = T { key1 :: Int ; key2 :: String ; key3 :: Double }
</PRE
><P
>Then the picker for that type looks like this
</P
><PRE
> xpT :: PU T
 xpT = xpWrap ( uncurry3 T, \ t -&gt; (key1 t, key2 t, key3 t) ) $
       xpTriple (xpElemWithAttrValue &quot;attr&quot; &quot;name&quot; &quot;key1&quot; $ xpickle)
                (xpElemWithAttrValue &quot;attr&quot; &quot;name&quot; &quot;key2&quot; $ xpText0)
                (xpElemWithAttrValue &quot;attr&quot; &quot;name&quot; &quot;key3&quot; $ xpickle)
</PRE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpLift"
><A NAME="v%3AxpLift"
></A
></A
><B
>xpLift</B
> ::  a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Lift a value to a pickler
</P
><P
>When pickling, nothing is encoded, when unpickling, the given value is inserted.
 This pickler always succeeds.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpLiftMaybe"
><A NAME="v%3AxpLiftMaybe"
></A
></A
><B
>xpLiftMaybe</B
> ::  <A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Lift a Maybe value to a pickler.
</P
><P
><TT
>Nothing</TT
> is mapped to the zero pickler, <TT
>Just x</TT
> is pickled with <TT
>xpLift x</TT
>.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpList"
><A NAME="v%3AxpList"
></A
></A
><B
>xpList</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> [a]</TD
></TR
><TR
><TD CLASS="doc"
><P
>Encoding of list values by pickling all list elements sequentially.
</P
><P
>Unpickler relies on failure for detecting the end of the list.
 The standard pickler for lists. Can also be used in combination with <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpWrap"
>xpWrap</A
></TT
>
 for constructing set and map picklers
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpList1"
><A NAME="v%3AxpList1"
></A
></A
><B
>xpList1</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> [a]</TD
></TR
><TR
><TD CLASS="doc"
><P
>Encoding of a none empty list of values
</P
><P
>Attention: when calling this pickler with an empty list,
 an internal error &quot;head of empty list is raised&quot;.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpMap"
><A NAME="v%3AxpMap"
></A
></A
><B
>xpMap</B
> :: <A HREF="/usr/share/doc/ghc/libraries/base/Data-Ord.html#t%3AOrd"
>Ord</A
> k =&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> k -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> v -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (<A HREF="/usr/share/doc/ghc/libraries/containers/Data-Map.html#t%3AMap"
>Map</A
> k v)</TD
></TR
><TR
><TD CLASS="doc"
><P
>Standard pickler for maps
</P
><P
>This pickler converts a map into a list of pairs.
 All key value pairs are mapped to an element with name (1.arg),
 the key is encoded as an attribute named by the 2. argument,
 the 3. arg is the pickler for the keys, the last one for the values
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpOption"
><A NAME="v%3AxpOption"
></A
></A
><B
>xpOption</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (<A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> a)</TD
></TR
><TR
><TD CLASS="doc"
><P
>Encoding of optional data by ignoring the Nothing case during pickling
 and relying on failure during unpickling to recompute the Nothing case
</P
><P
>The default pickler for Maybe types
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpPair"
><A NAME="v%3AxpPair"
></A
></A
><B
>xpPair</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>pickle a pair of values sequentially
</P
><P
>Used for pairs or together with wrap for pickling
 algebraic data types with two components
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpPrim"
><A NAME="v%3AxpPrim"
></A
></A
><B
>xpPrim</B
> :: (<A HREF="/usr/share/doc/ghc/libraries/base/Text-Read.html#t%3ARead"
>Read</A
> a, <A HREF="/usr/share/doc/ghc/libraries/base/Text-Show.html#t%3AShow"
>Show</A
> a) =&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle an arbitrary value by applyling show during pickling
 and read during unpickling.
</P
><P
>Real pickling is then done with <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpText"
>xpText</A
></TT
>.
 One of the most often used pimitive picklers. Applicable for all
 types which are instances of <TT
>Read</TT
> and <TT
>Show</TT
>
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpSeq"
><A NAME="v%3AxpSeq"
></A
></A
><B
>xpSeq</B
> ::  (b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; (a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="doc"
><P
>Combine two picklers sequentially.
</P
><P
>If the first fails during
 unpickling, the whole unpickler fails
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpText"
><A NAME="v%3AxpText"
></A
></A
><B
>xpText</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle a string into an XML text node
</P
><P
>One of the most often used primitive picklers. Attention:
 For pickling empty strings use <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpText0"
>xpText0</A
></TT
>. If the text has a more
 specific datatype than xsd:string, use <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpTextDT"
>xpTextDT</A
></TT
>
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpText0"
><A NAME="v%3AxpText0"
></A
></A
><B
>xpText0</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle a possibly empty string into an XML node.
</P
><P
>Must be used in all places, where empty strings are legal values.
 If the content of an element can be an empty string, this string disapears
 during storing the DOM into a document and reparse the document.
 So the empty text node becomes nothing, and the pickler must deliver an empty string,
 if there is no text node in the document.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpTextDT"
><A NAME="v%3AxpTextDT"
></A
></A
><B
>xpTextDT</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle a string into an XML text node
</P
><P
>Text pickler with a description of the structure of the text
 by a schema. A schema for a data type can be defined by <TT
><A HREF="Text-XML-HXT-Arrow-Pickle-Schema.html#v%3AscDT"
>scDT</A
></TT
>.
 In Text.XML.HXT.Arrow.Pickle.Schema there are some more functions for creating
 simple datatype descriptions.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpText0DT"
><A NAME="v%3AxpText0DT"
></A
></A
><B
>xpText0DT</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
> -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle a possibly empty string with a datatype description into an XML node.
</P
><P
>Like <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpText0"
>xpText0</A
></TT
> but with extra Parameter for datatype description as in <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpTextDT"
>xpTextDT</A
></TT
>.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpTree"
><A NAME="v%3AxpTree"
></A
></A
><B
>xpTree</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle an XmlTree by just adding it
</P
><P
>Usefull for components of type XmlTree in other data structures
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpTrees"
><A NAME="v%3AxpTrees"
></A
></A
><B
>xpTrees</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> [<A HREF="Text-XML-HXT-DOM-TypeDefs.html#t%3AXmlTree"
>XmlTree</A
>]</TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle a whole list of XmlTrees by just adding the list, unpickle is done by taking all element contens.
</P
><P
>This pickler should always combined with <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpElem"
>xpElem</A
></TT
> for taking the whole contents of an element.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpTriple"
><A NAME="v%3AxpTriple"
></A
></A
><B
>xpTriple</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> c -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> (a, b, c)</TD
></TR
><TR
><TD CLASS="doc"
>Like <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpPair"
>xpPair</A
></TT
> but for triples
</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpUnit"
><A NAME="v%3AxpUnit"
></A
></A
><B
>xpUnit</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/ghc-prim/GHC-Unit.html#t%3A%28%29"
>()</A
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpWrap"
><A NAME="v%3AxpWrap"
></A
></A
><B
>xpWrap</B
> ::  (a -&gt; b, b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="doc"
><P
>map value into another domain and apply pickler there
</P
><P
>One of the most often used picklers.
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpWrapMaybe"
><A NAME="v%3AxpWrapMaybe"
></A
></A
><B
>xpWrapMaybe</B
> ::  (a -&gt; <A HREF="/usr/share/doc/ghc/libraries/base/Data-Maybe.html#t%3AMaybe"
>Maybe</A
> b, b -&gt; a) -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a -&gt; <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> b</TD
></TR
><TR
><TD CLASS="doc"
><P
>like <TT
><A HREF="Text-XML-HXT-Arrow-Pickle.html#v%3AxpWrap"
>xpWrap</A
></TT
>, but if the inverse mapping is undefined, the unpickler fails
</P
><P
>Map a value into another domain. If the inverse mapping is
 undefined (Nothing), the unpickler fails
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpXmlText"
><A NAME="v%3AxpXmlText"
></A
></A
><B
>xpXmlText</B
> :: <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> <A HREF="/usr/share/doc/ghc/libraries/base/Data-Char.html#t%3AString"
>String</A
></TD
></TR
><TR
><TD CLASS="doc"
><P
>Pickle a string representing XML contents by inserting the tree representation into the XML document.
</P
><P
>Unpickling is done by converting the contents with
 <TT
><A HREF="Text-XML-HXT-Arrow-Edit.html#v%3AxshowEscapeXml"
>xshowEscapeXml</A
></TT
> into a string,
 this function will escape all XML special chars, such that pickling the value back becomes save.
 Pickling is done with <TT
><A HREF="Text-XML-HXT-Arrow-ReadDocument.html#v%3Axread"
>xread</A
></TT
>
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v:xpZero"
><A NAME="v%3AxpZero"
></A
></A
><B
>xpZero</B
> ::  <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3APU"
>PU</A
> a</TD
></TR
><TR
><TD CLASS="doc"
><P
>The zero pickler
</P
><P
>Encodes nothing, fails always during unpickling
</P
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>data</SPAN
>  <A NAME="t:Schema"
><A NAME="t%3ASchema"
></A
></A
><B
>Schema</B
>  </TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="ndoc"
>The datatype for modelling the structure of an
</TD
></TR
><TR
><TD CLASS="section4"
><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:Schema')" ALT="show/hide"
> Instances</TD
></TR
><TR
><TD CLASS="body"
><DIV ID="i:Schema" STYLE="display:block;"
><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="/usr/share/doc/ghc/libraries/base/Data-Eq.html#t%3AEq"
>Eq</A
> <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="/usr/share/doc/ghc/libraries/base/Text-Show.html#t%3AShow"
>Show</A
> <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>type</SPAN
> <A NAME="t:Schemas"
><A NAME="t%3ASchemas"
></A
></A
><B
>Schemas</B
> = [<A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ASchema"
>Schema</A
>]</TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>data</SPAN
>  <A NAME="t:DataTypeDescr"
><A NAME="t%3ADataTypeDescr"
></A
></A
><B
>DataTypeDescr</B
>  </TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="section4"
><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:DataTypeDescr')" ALT="show/hide"
> Instances</TD
></TR
><TR
><TD CLASS="body"
><DIV ID="i:DataTypeDescr" STYLE="display:block;"
><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="/usr/share/doc/ghc/libraries/base/Data-Eq.html#t%3AEq"
>Eq</A
> <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ADataTypeDescr"
>DataTypeDescr</A
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="/usr/share/doc/ghc/libraries/base/Text-Show.html#t%3AShow"
>Show</A
> <A HREF="Text-XML-HXT-Arrow-Pickle.html#t%3ADataTypeDescr"
>DataTypeDescr</A
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="botbar"
>Produced by <A HREF="http://www.haskell.org/haddock/"
>Haddock</A
> version 2.5.0</TD
></TR
></TABLE
></BODY
></HTML
>