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hxt-7.3: doc/hdoc/Control-Arrow-ArrowTree.html

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>Haskell Xml Toolbox 7.3: The complete API</TD
><TD CLASS="topbut"
><A HREF="http://darcs.fh-wedel.de/hxt/src/./Control/Arrow/ArrowTree.hs"
>Source code</A
></TD
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>Contents</A
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><A HREF="doc-index.html"
>Index</A
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><TD CLASS="modulebar"
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><TD
><FONT SIZE="6"
>Control.Arrow.ArrowTree</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: ArrowTree.hs,v 1.12 2006<EM
>11</EM
>30 16:05:24 hxml Exp $
</P
><P
>List arrows for tree processing.
</P
><P
>Trees that implement the <A HREF="Data-Tree-Class.html"
>Data.Tree.Class</A
> interface, can be processed
with these arrows.
</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"
><SPAN CLASS="keyword"
>class</SPAN
> (ArrowPlus a, <A HREF="Control-Arrow-ArrowIf.html#t%3AArrowIf"
>ArrowIf</A
> a) =&gt; <A HREF="#t%3AArrowTree"
>ArrowTree</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%3AgetChildren"
>getChildren</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AgetNode"
>getNode</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) b</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AsetChildren"
>setChildren</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; [t b] -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AsetNode"
>setNode</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; b -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AchangeChildren"
>changeChildren</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; ([t b] -&gt; [t b]) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AchangeNode"
>changeNode</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; (b -&gt; b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AprocessChildren"
>processChildren</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AreplaceChildren"
>replaceChildren</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3A%2F%3E"
>(/&gt;)</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3A%3C%2F"
>(&lt;/)</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3Adeep"
>deep</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3Adeepest"
>deepest</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3Amulti"
>multi</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) c -&gt; a (t b) c</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AprocessBottomUp"
>processBottomUp</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AprocessTopDown"
>processTopDown</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AprocessBottomUpWhenNot"
>processBottomUpWhenNot</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AprocessTopDownUntil"
>processTopDownUntil</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AinsertChildrenAt"
>insertChildrenAt</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; Int -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AinsertChildrenAfter"
>insertChildrenAfter</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="#v%3AinsertTreeTemplate"
>insertTreeTemplate</A
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; [<A HREF="Control-Arrow-ArrowIf.html#t%3AIfThen"
>IfThen</A
> (a (t b) c) (a (t b) (t b))] -&gt; a (t b) (t b)</TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>class</SPAN
> <A HREF="#t%3ATree"
>Tree</A
> t </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"
><SPAN CLASS="keyword"
>class</SPAN
> (ArrowPlus a, <A HREF="Control-Arrow-ArrowIf.html#t%3AArrowIf"
>ArrowIf</A
> a) =&gt; <A NAME="t%3AArrowTree"
></A
><B
>ArrowTree</B
> a  <SPAN CLASS="keyword"
>where</SPAN
></TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="ndoc"
><P
>The interface for tree arrows
</P
><P
>all functions have default implementations
</P
></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%3AgetChildren"
></A
><B
>getChildren</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>select the children of the root of a tree
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AgetNode"
></A
><B
>getNode</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) b</TD
></TR
><TR
><TD CLASS="doc"
>select the attribute of the root of a tree
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AsetChildren"
></A
><B
>setChildren</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; [t b] -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>substitute the children of the root of a tree
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AsetNode"
></A
><B
>setNode</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; b -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>substitute the attribute of the root of a tree
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AchangeChildren"
></A
><B
>changeChildren</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; ([t b] -&gt; [t b]) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>edit the children of the root of a tree
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AchangeNode"
></A
><B
>changeNode</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; (b -&gt; b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>edit the attribute of the root of a tree
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AprocessChildren"
></A
><B
>processChildren</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>apply an arrow element wise to all children of the root of a tree
 collect these results and substitute the children with this result
</P
><P
>example: <TT
> processChildren isText </TT
> deletes all subtrees, for which isText does not hold
</P
><P
>example: <TT
> processChildren (none `when` isCmt) </TT
> removes all children, for which isCmt holds
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AreplaceChildren"
></A
><B
>replaceChildren</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>similar to processChildren, but the new children are computed by processing
 the whole input tree
</P
><P
>example: <TT
> replaceChildren (deep isText) </TT
> selects all subtrees for which isText holds
 and substitutes the children component of the root node with this list
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3A%2F%3E"
></A
><B
>(/&gt;)</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>pronounced &quot;slash&quot;, meaning g inside f
</P
><P
>defined as <TT
> f /&gt; g = f &gt;&gt;&gt; getChildren &gt;&gt;&gt; g </TT
>
</P
><P
>example: <TT
> hasName &quot;html&quot; /&gt; hasName &quot;body&quot; /&gt; hasName &quot;h1&quot; </TT
>
</P
><P
>This expression selects
 all &quot;h1&quot; elements in the &quot;body&quot; element of an &quot;html&quot; element, an expression, that
 corresponds 1-1 to the XPath selection path &quot;html/body/h1&quot; 
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3A%3C%2F"
></A
><B
>(&lt;/)</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>pronounced &quot;outside&quot; meaning f containing g
</P
><P
>defined as <TT
> f &lt;/ g = f `containing` (getChildren &gt;&gt;&gt; g) </TT
>
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3Adeep"
></A
><B
>deep</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>recursively searches a whole tree for subtrees, for which a predicate holds.
 The search is performed top down. When a tree is found, this becomes an element of the result
 list. The tree found is not further examined for any subtress, for which the predicate also could hold.
 See <TT
><A HREF="Control-Arrow-ArrowTree.html#v%3Amulti"
>multi</A
></TT
> for this kind of search.
</P
><P
>example: <TT
> deep isHtmlTable </TT
> selects all top level table elements in a document
 (with an appropriate definition for isHtmlTable) but no tables occuring within a table cell.
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3Adeepest"
></A
><B
>deepest</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>recursively searches a whole tree for subrees, for which a predicate holds.
 The search is performed bottom up.
</P
><P
>example: <TT
> deepest isHtmlTable </TT
> selects all innermost table elements in a document
 but no table elements containing tables. See <TT
><A HREF="Control-Arrow-ArrowTree.html#v%3Adeep"
>deep</A
></TT
> and <TT
><A HREF="Control-Arrow-ArrowTree.html#v%3Amulti"
>multi</A
></TT
> for other search strategies.
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3Amulti"
></A
><B
>multi</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) c -&gt; a (t b) c</TD
></TR
><TR
><TD CLASS="doc"
><P
>recursively searches a whole tree for subtrees, for which a predicate holds.
 The search is performed top down. All nodes of the tree are searched, even within the
 subtrees of trees for which the predicate holds.
</P
><P
>example: <TT
> multy isHtmlTable </TT
> selects all table elements, even nested ones.
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AprocessBottomUp"
></A
><B
>processBottomUp</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>recursively transforms a whole tree by applying an arrow to all subtrees,
 this is done bottom up depth first, leaves first, root as last tree
</P
><P
>example: <TT
> processBottomUp (getChildren `when` isHtmlFont) </TT
> removes all font tags in a HTML document, even nested ones
 (with an appropriate definition of isHtmlFont)
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AprocessTopDown"
></A
><B
>processTopDown</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>similar to <TT
><A HREF="Control-Arrow-ArrowTree.html#v%3AprocessBottomUp"
>processBottomUp</A
></TT
>, but recursively transforms a whole tree by applying an arrow to all subtrees
 with a top down depth first traversal strategie. In many cases <TT
><A HREF="Control-Arrow-ArrowTree.html#v%3AprocessBottomUp"
>processBottomUp</A
></TT
> and <TT
><A HREF="Control-Arrow-ArrowTree.html#v%3AprocessTopDown"
>processTopDown</A
></TT
>
 give same results.
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AprocessBottomUpWhenNot"
></A
><B
>processBottomUpWhenNot</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>recursively transforms a whole tree by applying an arrow to all subtrees,
 but transformation stops when a predicte does not hold for a subtree,
 leaves are transformed first
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AprocessTopDownUntil"
></A
><B
>processTopDownUntil</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>recursively transforms a whole tree by applying an arrow to all subtrees,
 but transformation stops when a tree is successfully transformed.
 the transformation is done top down
</P
><P
>example: <TT
> processTopDownUntil (isHtmlTable `guards` tranformTable) </TT
>
 transforms all top level table elements into something else, but inner tables remain unchanged
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AinsertChildrenAt"
></A
><B
>insertChildrenAt</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; Int -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>computes a list of trees by applying an arrow to the input
 and inserts this list in front of index i in the list of children
</P
><P
>example: <TT
> insertChildrenAt 0 (deep isCmt) </TT
> selects all subtrees for which isCmt holds
 and copies theses in front of the existing children
</P
></TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AinsertChildrenAfter"
></A
><B
>insertChildrenAfter</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; a (t b) (t b) -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
>similar to <TT
><A HREF="Control-Arrow-ArrowTree.html#v%3AinsertChildrenAt"
>insertChildrenAt</A
></TT
>, but the insertion position is searched with a predicate
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="decl"
><A NAME="v%3AinsertTreeTemplate"
></A
><B
>insertTreeTemplate</B
> :: <A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> t =&gt; a (t b) (t b) -&gt; [<A HREF="Control-Arrow-ArrowIf.html#t%3AIfThen"
>IfThen</A
> (a (t b) c) (a (t b) (t b))] -&gt; a (t b) (t b)</TD
></TR
><TR
><TD CLASS="doc"
><P
>an arrow for inserting a whole subtree with some holes in it (a template)
 into a document. The holes can be filled with contents from the input.
</P
><P
>Example
</P
><PRE
> insertTreeTemplateTest	:: ArrowXml a =&gt; a b XmlTree
 insertTreeTemplateTest
     = doc
       &gt;&gt;&gt;
       insertTemplate template pattern
     where
     doc								-- the input data
 	= constA &quot;&lt;x&gt;&lt;y&gt;The Title&lt;/y&gt;&lt;z&gt;The content&lt;/z&gt;&lt;/x&gt;&quot;
 	  &gt;&gt;&gt; xread
     template								-- the output template with 2 holes: xxx and yyy
 	= constA &quot;&lt;html&gt;&lt;head&gt;&lt;title&gt;xxx&lt;/title&gt;&lt;/head&gt;&lt;body&gt;&lt;h1&gt;yyy&lt;/h1&gt;&lt;/body&gt;&lt;/html&gt;&quot;
 	  &gt;&gt;&gt; xread
     pattern
 	= [ hasText (== &quot;xxx&quot;)						-- fill the xxx hole with the input contents from element &quot;x/y&quot;
 	    :-&gt; ( getChildren &gt;&gt;&gt; hasName &quot;y&quot; &gt;&gt;&gt; deep isText )
 
 	  , hasText (== &quot;yyy&quot;)						-- fill the yyy hole with the input contents from element &quot;x/z&quot;
 	    :-&gt; ( getChildren &gt;&gt;&gt; hasName &quot;z&quot; &gt;&gt;&gt; getChildren )
 	  ]
</PRE
><P
>computes the XML tree for the following document
</P
><PRE
> &quot;&lt;html&gt;&lt;head&gt;&lt;title&gt;The Title&lt;/title&gt;&lt;/head&gt;&lt;body&gt;&lt;h1&gt;The content&lt;/h1&gt;&lt;/body&gt;&lt;/html&gt;&quot;
</PRE
></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:ArrowTree')" ALT="show/hide"
> Instances</TD
></TR
><TR
><TD CLASS="body"
><DIV ID="i:ArrowTree" STYLE="display:block;"
><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="Control-Arrow-ArrowTree.html#t%3AArrowTree"
>ArrowTree</A
> <A HREF="Control-Arrow-IOListArrow.html#t%3AIOLA"
>IOLA</A
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="Control-Arrow-ArrowTree.html#t%3AArrowTree"
>ArrowTree</A
> <A HREF="Control-Arrow-ListArrow.html#t%3ALA"
>LA</A
></TD
></TR
><TR
><TD CLASS="decl"
><A HREF="Control-Arrow-ArrowTree.html#t%3AArrowTree"
>ArrowTree</A
> (<A HREF="Control-Arrow-IOStateListArrow.html#t%3AIOSLA"
>IOSLA</A
> s)</TD
></TR
><TR
><TD CLASS="decl"
><A HREF="Control-Arrow-ArrowTree.html#t%3AArrowTree"
>ArrowTree</A
> (<A HREF="Control-Arrow-StateListArrow.html#t%3ASLA"
>SLA</A
> s)</TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></TD
></TR
><TR
><TD CLASS="s15"
></TD
></TR
><TR
><TD CLASS="decl"
><SPAN CLASS="keyword"
>class</SPAN
> <A NAME="t%3ATree"
></A
><B
>Tree</B
> t </TD
></TR
><TR
><TD CLASS="body"
><TABLE CLASS="vanilla" CELLSPACING="0" CELLPADDING="0"
><TR
><TD CLASS="ndoc"
>The interface for trees
</TD
></TR
><TR
><TD CLASS="s8"
></TD
></TR
><TR
><TD CLASS="section4"
><IMG SRC="minus.gif" CLASS="coll" ONCLICK="toggle(this,'i:Tree')" ALT="show/hide"
> Instances</TD
></TR
><TR
><TD CLASS="body"
><DIV ID="i:Tree" STYLE="display:block;"
><TABLE CLASS="vanilla" CELLSPACING="1" CELLPADDING="0"
><TR
><TD CLASS="decl"
><A HREF="Control-Arrow-ArrowTree.html#t%3ATree"
>Tree</A
> <A HREF="Data-Tree-NTree-TypeDefs.html#t%3ANTree"
>NTree</A
></TD
></TR
></TABLE
></DIV
></TD
></TR
></TABLE
></TD
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><TD CLASS="s15"
></TD
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><TD CLASS="botbar"
>Produced by <A HREF="http://www.haskell.org/haddock/"
>Haddock</A
> version 0.8</TD
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