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<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
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<page name="examples">
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<title>Advanced examples</title>
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<left>
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<p>This page presents some sample CDuce programs.</p>
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<boxes-toc/>
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<p>See also:</p>
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<local-links href="index,proto,memento"/>
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</left>
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<box title="Advanced examples" link="start">
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This page presents some advanced programming examples in CDuce. <b
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style="color:#FF0080">If you never saw CDuce programs before, this is the wrong
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page</b> to start with. Rather follow our <local href="tutorial"/>, or test the
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simple examples in our <a href="/cgi-bin/cduce">on line demo</a>.
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</box>
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<box title="Our canonical example" link="sort">
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<p>
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The example below is the one we use to demonstrate
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how overloaded functions can avoid duplicating code.
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Without overloaded functions, we would need to define
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two mutually recursive functions in order to type-check
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the transformation. Here, two constraints
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in the (highlighted) function interface
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can express precisely the behaviour of the function.
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A detailed explanation of the code can be found <a href="tutorial_overloading.html#canonical">here</a>.
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</p>
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<sample>
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<include-verbatim file="overloading.cd"/>
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</sample>
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</box>
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<box title="Datatypes + first-class functions" link="data">
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<p>
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The program below shows how to simulate ML data types in CDuce.
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It implements a (naive backtracking) regular expression recognizer.
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The examples also demonstrate the use of first-class functions
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(used as continuations).
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</p>
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<p>
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Exercise for the reader: show that the algorithm may not terminate for
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some special regular expressions.
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</p>
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<sample highlight="false">
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<include-verbatim file="regexp.cd"/>
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</sample>
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</box>
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<box title="CDuce quine" link="quine">
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<p>
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A quine (a.k.a. self-rep) is a program that produces its own source
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code. Here is an example of a quine written in CDuce.
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</p>
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<sample highlight="false">
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<include-verbatim file="quine.cd"/>
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</sample>
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</box>
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<box title="The script that generates this site" link="site">
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<p>
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The script below is one of the longest CDuce application ever written
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;-) It is used to produce all the pages of this web site (except
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the <local href="proto">web prototype</local> which is
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a CGI script written in OCaml). CDuce type system ensures
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that produced pages are valid w.r.t XHTML 1.0 Strict.
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</p>
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<p>
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This program features both XML and text-content manipulation.
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It also demonstrates the use of non-XML internal data structures.
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Here, a tree represents internally the site
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structure, and a list represents the path from the
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root to the current page (in order to display the "You're here" line).
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</p>
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<sample highlight="false">
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<include-verbatim file="site.cd"/>
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</sample>
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</box>
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</page>
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