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<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
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<page name="index">
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<title>Home page</title>
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<banner>
  <img title="CDuce" src="img/cduce_logo.jpg" width="400" height="206"
       alt="CDuce"/>
</banner>

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<left>
<p>On this page:</p>
<boxes-toc/>
<p>Under this page:</p>
<pages-toc/>
</left>

<external href="/cgi-bin/cduce" title="Online demo" name="proto"/>
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<include file="download.xml"/>
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<include file="bench.xml"/>
<include file="papers.xml"/>
<include file="examples.xml"/>
<include file="team.xml"/>
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<include file="manual.xml"/>
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<include file="sitemap.xml"/>

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<left>
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<p> CDuce ("seduce") is a new typed functional language with
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innovative features.</p>
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<p> Although CDuce is a general programming language, it features
several characteristics that make it adapted to XML documents
manipulation (transformation, extraction of information, creation of
documents).  
<a href="http://www.w3.org/XML/">XML</a> is a syntax to
describe tree-like documents (aka semi-structured data), and XML
documents often come with a description of their type. The type is
expressed in a system like DTD, or 
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<a href="http://www.w3.org/XML/Schema">XML Schema</a>.
XML types play a central role in CDuce.
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  </p>
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</left>
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<left>
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<p> All pages of this site were automatically generated from an XML description of
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the content by <a href="examples.html#site">the following CDuce program</a>.
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</p><p> 
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<img src="img/cducepower2.jpg" alt="Powered by CDuce"/></p>
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</left>
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<box title="What is CDuce ?" link="whatis">

<p> <b>CDuce</b> is modern programming language, adapted to the
manipulation of XML documents.  It is developped by the <a
href="http://www.di.ens.fr/~castagna/EQUIPE"><b>Languages</b></a>
group of ENS in Paris and the <a
href="http://www.lri.fr/bd"><b>Databases</b></a> group of LRI in
Orsay, two <a href="http://www.cnrs.fr">CNRS</a> labs.
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See also the <local href="team">CDuce team</local> page,
our <local href="papers">technical papers</local>.
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</p>
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<section title="Online running prototype">
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<p> To get a feeling of CDuce,
you can play with the <local href="proto">online prototype</local>,
try the examples and modify them. We also have some 
<local href="examples">larger examples</local>. </p>
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<p>We are planning to distribute a stable release in the next
few weeks. To help us prepare this release, you can download a
<local href="download">beta version</local>, and send your comments.
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</p>

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</section>
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</box>

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<box title="Design and features" link="design">
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<p> Our point of view and our guideline for the design of CDuce is
that a programming language for XML should take XML types (
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DTD, XML Schema, Relax-NG, ...) seriously. The benefit are the following:</p>
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<ul>
<li> <b>static verifications</b>
(e.g.: ensure that a transformation produces a valid document);</li>
<li> in particular, we aim at <b>smooth and safe</b> compositions
of XML transformations, and incremental programming;</li>
<li> static <b>optimizations</b> and <b>efficient execution model</b>
(knowing the type of a document is crucial to extract information 
efficiently).</li> 
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</ul>

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<p>
Some of CDuce peculiar features:
</p>
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<ul>
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<li> XML objects can be manipulated as first-class citizen values:
     elements, sequences, tags, characters and strings, attribute
     sets; sequences of XML elements can be specified by 
     <b>regular expressions</b>, which also apply to
     characters strings; </li>
<li> functions themselves are <b>first-class</b> values, they
     can be manipulated, stored in data structure, returned by
     a function,...</li>
<li> a powerful <b>pattern matching</b> operation can perform
     complex extractions from sequences of XML elements; </li>
<li> a rich <b>type algebra</b>, with recursive types and arbitrary
     boolean combinations (union, intersection, complement) allows
     precise definitions of data structures and XML types;
     <b>general purpose types</b> and types constructors are taken seriously
     (products, extensible records, arbitrary precision integers with interval
     constraints,  Unicode characters);</li>
<li> <b>polymorphism</b> through a natural notion of <b>subtyping</b>,
     and <b>overloaded functions</b> with dynamic dispatch; </li>
<li> an highly-effective <b>type-driven compilation schema</b>. </li>
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</ul>

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<p>CDuce is fast, functional,
type-safe, and <b>conforms to basic standards</b>: <a href="http://www.unicode.org">Unicode</a>, <a href="http://www.w3.org/XML/">XML</a>, <a href="http://www.w3.org/TR/REC-xml#dt-doctype">DTD</a>,
<a href="http://www.w3.org/TR/REC-xml-names/">Namespaces</a> are fully supported, partial support of <a href="http://www.w3.org/TR/xmlschema-1/">XML Schema</a> validation is
in alpha testing (and undocumented) while queries are being
implemented.
</p>

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<p>
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<local href="bench">Preliminary benchmarks</local> suggest that despite the
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overhead for static type verification, a CDuce
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program can run faster (30% to 60%) than an equivalent XSLT
style-sheet (we performed benchmarks with
the xsltproc tools from the Gnome libxslt library).
</p>
</box>

<box title="Research directions" link="research">
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<p>Our plans concerning the design of the core language
include:</p>
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<ul>
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 <li>a module system to support incremental programming;</li>
 <li>parametric polymorphism;</li>
 <li>XML-friendly primitives, to mimic XSLT transformations.</li>
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</ul>

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<p>
Apart from the core language design and implementation, 
our research projects include:
</p>
<ul>
<li> integration of a <b>query sub-language</b> into CDuce, using
     types as a primary optimization strategy for request evaluation;</li>
<li> study of <b>security</b> (confidentiality, ...) properties in the
     setting of XML transformations.</li>
</ul>
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<p>
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We wrote several <local href="papers">technical papers</local> about
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the language design and its theoretical foundations.
</p>
</box>
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<box title="XDuce and CDuce" link="xduce">
<p>
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The starting point of our work on CDuce was the
<a href="http://xduce.sourceforge.net/">XDuce</a> language developped
at the UPenn DB group. Many of CDuce features originate from XDuce.
Some of our achievements:
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</p>
<ul>
<li>integration of first-class and overloaded functions, arbitrary boolean
    connectives, and extensible (or not) records, to the semantic
    definition of subtyping;</li>
<li>a subtyping algorithm without backtracking;</li>
<li>extending pattern matching to capture non consecutive
    subsequences; removing tail condition for exact matching
    (they arrived independently to another solution);</li>
<li>efficient evaluation model that takes profit of static type information;</li>
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</ul>
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<p>
Of course, the work on XDuce continued during our, and they
developped nice ideas: mixed attribute-element types (same
expressive power as our records, but they can sometimes avoid exponential
explosion where we cannot); powerful filter operation.
</p>
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</box>

<box title="Related links" link="links">
<ul>
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<li> <link url="http://www.w3.org/XML/"
title="Extensible Markup Language (XML)"> The W3C page on XML. </link>
</li>
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<li> <link url="http://www.research.avayalabs.com/user/wadler/xml/"
title="XML: Some hyperlinks minus the hype"> By Philip Wadler. </link>
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</li>
<li> <link url="http://xduce.sourceforge.net/"
title="XDuce"> XDuce home page. </link> </li>
</ul> </box>
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</p>
<p>
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<a href="mailto:Alain.Frisch@ens.fr">Webmaster</a> -
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<local href="sitemap">Site map</local>
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</page>