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<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
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<page>
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<title>CDuce memento</title>
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<banner> CDuce memento </banner>
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<!-- ********* Left panel ********* -->
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<navig>
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<toc/>
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<box>
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<p>
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This page briefly presents the syntax of the CDuce language.
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</p>
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<ul>
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<li><a href="/cgi-bin/cduce">Online demo</a></li>
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<li><a href="/">Home page</a></li>
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</ul>
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</box>
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</navig>
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<!-- ********* Main panel ********* -->
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<main>
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<box title="Identifiers" link="id">
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<ul>
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<li> Type and Pattern identifiers: words formed by of unicode letters and and
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the underscore "_" character, starting by a capitalized letter. </li>
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<li> value identifiers: words formed by of unicode letters and the underscore "
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_" character, starting by a capitalized letter or underscore.</li>
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</ul>
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</box>
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<box title="Scalars" link="scalars">
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<ul>
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<li>Large integers:
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<ul>
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<li>Values: <duce>0,1,2,3,...</duce> </li>
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<li>Types: intervals <duce>-*--10, 20--30, 50--*, ...</duce>,
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singletons <duce>0,1,2,3,...</duce> </li>
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<li>Operators: <duce>+,-,/,*,div,mod, int_of</duce> </li>
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</ul>
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</li>
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<li>Unicode characters:
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<ul>
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<li>Values: <duce>'a','b','c'...</duce> </li>
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<li>Types: intervals <duce>'a'--'z', '0'--'9'</duce>,
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singletons <duce>'a','b','c',...</duce> </li>
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</ul>
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</li>
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<li>Symbolic atoms:
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<ul>
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<li>Values: <duce>`A, `B, `a, `b, `true, `false, ...</duce> </li>
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<li>Types: singletons <duce>`A, `B, ...</duce> </li>
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<li>Operators: <duce>atom_of</duce> : String -> Atom</li>
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</ul>
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</li>
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</ul>
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</box>
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<box title="Operators" link="op">
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<ul>
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<li>Infix:
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<br/> <duce>@</duce> : String,String -> String
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<br/> <duce>+,*,-,div,mod</duce> : Integer,Integer -> Integer
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<br/> <duce>=, <<, <=, >>, >= </duce> :
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Integer,Integer -> Bool = <duce>`true | `false</duce>
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</li>
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<li>Prefix:
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<br/><duce>load_xml,load_html</duce> : String -> Any,
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<br/><duce>dump_to_file</duce> : String -> String -> Any,
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<br/><duce>print_xml</duce> : Any -> String
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<br/><duce>print</duce> : String -> []
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<br/><duce>int_of</duce> : [('0'--'9')+] -> Integer
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<br/><duce>string_of</duce> : Integer -> String
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</li>
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<li>Postfix:
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<br/><duce>?,*,+,??,*?,+?</duce> : for regexp
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</li>
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</ul>
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</box>
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<box title="Pairs" link="pair">
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<ul>
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<li>Expressions: <duce>(e1,e2)</duce> </li>
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<li>Types and patterns: <duce>(t1,t2)</duce> </li>
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<li>Note: tuples are right-associative pairs; e.g.:
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<duce>(1,2,3)=(1,(2,3))</duce> </li>
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<li>When a capture variable appears on both side of a pair pattern,
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the two captured values are paired
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together (e.g. <duce>match (1,2,3) with (x,(_,x)) -> x ==>
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(1,3)</duce>). </li>
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</ul>
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</box>
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<box title="Sequences" link="seq">
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<ul>
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<li>Expressions: <duce>[ 1 2 3 ]</duce>,
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which is syntactic sugar for <duce>(1,(2,(3,`nil)))</duce> </li>
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<li>A sub-sequence can be escaped by !: <duce>[ 1 2 ![ 3 4 ] 5
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]</duce> is then equal to <duce>[ 1 2 3 4 5 ]</duce> . </li>
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<li>Types and patterns : <duce>[ R ]</duce> where <duce>R</duce> is
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a regular expression built on types and patterns:
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<ul>
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<li>A type or a pattern is a regexp by itself, matching a single
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element of the sequence </li>
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<li>Postfix repetition operators: <duce>*,+,?</duce>
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and the ungreedy variants (for patterns) <duce>*?, +?
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,??</duce></li>
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<li>Concatenation of regexps</li>
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<li>For patterns, sequence capture variable <duce>x::R</duce> </li>
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</ul>
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</li>
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<li>It is possible to specify a tail, for expressions, types, and patterns;
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e.g.: <duce>[ x::Int*; q ]</duce> </li>
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<li>Map: <duce>map e with p1 -> e1 | ... | pn -> en</duce>.
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Each element of e must be matched. </li>
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<li>Transform: <duce>transform e with p1 -> e1 | ... | pn -> en</duce>.
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Unmatched elements are discarded; each branch returns a sequence
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and all the resulting sequences are concatenated together. </li>
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<li>Operators: concatenation <duce>e1 @ e2 = [ !e1 !e2 ]</duce>,
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flattening <duce>flatten e = transform e with x -> x</duce>.
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</li>
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</ul>
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</box>
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<box title="Record" link="record">
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<ul>
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<li>Records litteral <duce>{ l1 = e1; ...; ln = en }</duce></li>
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<li>Types: <duce>{| l1 = t1; ...; ln = tn |}</duce> (closed, no more
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fields allowed), <duce>>{ l1 = t1; ...; ln = tn }</duce> (open,
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any other field allowed). Optional fields: <duce>li =? ti</duce>
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instead of <duce>li = ti</duce>.</li>
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<li>Record concatenation: <duce>e1 + e2</duce>
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(priority to the fields from the right argument) </li>
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<li>Field removal: <duce>e1 \ l</duce> (does nothing if the
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field <duce>l</duce> is not present)</li>
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<li>Field access: <duce>e1 . l</duce></li>
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<li>Record: <duce>{ l1 = p1; ...; ln = pn }</duce></li>
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</ul>
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</box>
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<box title="Strings" link="string">
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<ul>
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<li>Strings are actually sequences of characters.</li>
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<li>Expressions: <duce>"abc", [ 'abc' ], [ 'a' 'b' 'c' ]</duce>. </li>
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<li>Operators: <duce>string_of, print, dump_to_file</duce></li>
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<li><duce>PCDATA</duce> means <duce>Char*</duce> inside regular expressions</li>
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</ul>
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</box>
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<box title="XML elements" link="xml">
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<ul>
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<li>Expressions: <duce> <(tag) (attr)>content</duce> </li>
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<li>If the tag is an atom <duce>`X</duce>, it can be written
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<duce>X</duce> (without the <duce>(..)</duce>).
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Similarly, parenthesis and curly braces may be omitted
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when attr is a record <duce>l1=e1;...;ln=en</duce>.
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E.g: <duce><a href="abc">[ 'abc' ]</duce>.</li>
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<li>Types and patterns: same notations.</li>
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<li>Operators: <duce>load_xml : String -> Any; print_xml : Any -> String</duce>
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</li>
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</ul>
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</box>
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<box title="Functions" link="fun">
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<ul>
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<li>Expressions:
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<ul>
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<li>General form: <duce>fun f (t1->s1;...;tn->sn)
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p1 -> e1 | ... | pn -> en</duce> (<duce>f</duce> is optional) </li>
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<li>Simple function: <duce>fun f (p : t) : s = e</duce>,
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equivalent to <duce>fun f (t -> s) p -> e</duce> </li>
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<li>Multiple arguments: <duce>fun f (p1 : t1, p2 : t2,...) : s =
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e</duce>, equivalent to <duce>fun f ((p1,p2,...):(t1,t2,...)) : s
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= e</duce> </li>
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</ul>
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</li>
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<li>Types: <duce>t -> s</duce> </li>
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</ul>
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</box>
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<box title="Pattern matching, exceptions, ..." link="match">
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<ul>
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<li>Type restriction: <duce>(e : t)</duce> (forgets any more precise
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type for <duce>e</duce>) </li>
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<li>Pattern matching: <duce>match e with p1 -> e1 | ... | pn ->
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en</duce></li>
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<li>Local binding: <duce>let p = e1 in e2</duce>, equivalent to
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<duce>match e1 with p -> e2</duce>;
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<duce>let p : t = e1 in e2</duce> equivalent to
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<duce>let p = (e1 : t) in e2</duce> </li>
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<li>If-then-else: <duce>if e1 then e2 else e3</duce>, equivalent to
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<duce>match e1 with `true -> e2 | `false -> e3</duce></li>
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<li>Exceptions: <ul>
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<li>Raise exception: <duce>raise e</duce></li>
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<li>Handle exception: <duce>try e with p1 -> e1 | ... | pn ->
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en</duce></li>
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</ul> </li>
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</ul>
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</box>
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<box title="More about types and patterns" link="type">
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<ul>
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<li>Boolean connectives: <duce>&,|,\</duce> (<duce>|</duce> is
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first-match). </li>
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<li>Empty and universal types: <duce>Empty,Any</duce> or
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<duce>_</duce>.</li>
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<li>Recursive types and patterns: <duce>t where T1 = t2 and ... and
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Tn = tn</duce>.</li>
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<li>Capture variable: <duce>x</duce>. </li>
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<li>Default values: <duce>(x := c)</duce>. </li>
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</ul>
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</box>
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<box title="Toplevel statements" link="type">
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<ul>
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<li>Type declarations: <duce>type T = t</duce>.</li>
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<li>Source inclusion: <duce>include </duce> <i> filename_string</i></li>
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<li>Debug directives: <duce>debug </duce> <i> directive argument</i> <br/>
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where <i> directive</i> is one of the following: <duce>accept</duce>,
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<duce>subtype</duce>, <duce>compile</duce>.
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</li>
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</ul>
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</box>
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<meta>
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<p>
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This page has been generated by a CDuce program.
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</p>
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<p><a href="/">Home page</a> - <a href="mailto:Alain.Frisch@ens.fr">Webmaster</a>
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</p>
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</meta>
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</main>
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</page>
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