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<?xml version="1.0" encoding="ISO-8859-1" standalone="yes"?>
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<page name="memento">
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<title>Memento</title>
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<left>
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<p>This page briefly presents the syntax of the CDuce language.</p>
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<boxes-toc/>
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<p>See also:</p>
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<local-links href="index,proto,papers"/>
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</left>
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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: <code>0,1,2,3,...</code> </li>
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<li>Types: intervals <code>-*--10, 20--30, 50--*, ...</code>,
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singletons <code>0,1,2,3,...</code> </li>
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<li>Operators: <code>+,-,/,*,div,mod, int_of</code> </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: <code>'a','b','c'...</code> </li>
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<li>Types: intervals <code>'a'--'z', '0'--'9'</code>,
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singletons <code>'a','b','c',...</code> </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: <code>`A, `B, `a, `b, `true, `false, ...</code> </li>
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<li>Types: singletons <code>`A, `B, ...</code> </li>
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<li>Operators: <code>atom_of</code> : String -> Atom</li>
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<li>CDuce also supports <local href="namespaces">XML Namespaces</local></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/> <code>@</code> : concatenation of sequences
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<br/> <code>+,*,-,div,mod</code> : Integer,Integer -> Integer
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<br/> <code>=, <<, <=, >>, >= </code> :
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Integer,Integer -> Bool = <code>`true | `false</code>
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</li>
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<li>Prefix:
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<br/><code>load_xml,load_html</code> : String -> Any,
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<br/><code>dump_to_file</code> : String -> String -> Any,
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<br/><code>print_xml</code> : Any -> String
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<br/><code>print</code> : String -> []
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<br/><code>int_of</code> : [('0'--'9')+] -> Integer
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<br/><code>string_of</code> : Integer -> String
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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: <code>(e1,e2)</code> </li>
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<li>Types and patterns: <code>(t1,t2)</code> </li>
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<li>Note: tuples are right-associative pairs; e.g.:
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<code>(1,2,3)=(1,(2,3))</code> </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. <code>match (1,2,3) with (x,(_,x)) -> x ==>
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(1,3)</code>). </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: <code>[ 1 2 3 ]</code>,
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which is syntactic sugar for <code>(1,(2,(3,`nil)))</code> </li>
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<li>A sub-sequence can be escaped by !: <code>[ 1 2 ![ 3 4 ] 5
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]</code> is then equal to <code>[ 1 2 3 4 5 ]</code> . </li>
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<li>Types and patterns : <code>[ R ]</code> where <code>R</code> 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: <code>*,+,?</code>
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and the ungreedy variants (for patterns) <code>*?, +?
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,??</code></li>
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<li>Concatenation of regexps</li>
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<li>For patterns, sequence capture variable <code>x::R</code> </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.: <code>[ x::Int*; q ]</code> </li>
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<li>Map: <code>map e with p1 -> e1 | ... | pn -> en</code>.
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Each element of e must be matched. </li>
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<li>Transform: <code>transform e with p1 -> e1 | ... | pn -> en</code>.
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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 <code>e1 @ e2 = [ !e1 !e2 ]</code>,
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flattening <code>flatten e = transform e with x -> x</code>.
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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 <code>{ l1 = e1; ...; ln = en }</code></li>
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<li>Types: <code>{| l1 = t1; ...; ln = tn |}</code> (closed, no more
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fields allowed), <code>>{ l1 = t1; ...; ln = tn }</code> (open,
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any other field allowed). Optional fields: <code>li =? ti</code>
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instead of <code>li = ti</code>.</li>
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<li>Record concatenation: <code>e1 + e2</code>
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(priority to the fields from the right argument) </li>
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<li>Field removal: <code>e1 \ l</code> (does nothing if the
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field <code>l</code> is not present)</li>
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<li>Field access: <code>e1 . l</code></li>
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<li>Record: <code>{ l1 = p1; ...; ln = pn }</code></li>
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<li>Labels are in fact Qualified Names (see <local href="namespaces"/>)</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: <code>"abc", [ 'abc' ], [ 'a' 'b' 'c' ]</code>. </li>
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<li>Operators: <code>string_of, print, dump_to_file</code></li>
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<li><code>PCDATA</code> means <code>Char*</code> 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: <code> <(tag) (attr)>content</code> </li>
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<li>If the tag is an atom <code>`X</code>, it can be written
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<code>X</code> (without the <code>(..)</code>).
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Similarly, parenthesis and curly braces may be omitted
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when attr is a record <code>l1=e1;...;ln=en</code>
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(semicolon can also be omitted in this case).
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E.g: <code><a href="abc">[ 'abc' ]</code>.</li>
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<li>Types and patterns: same notations.</li>
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<li>Operators: <code>load_xml : String -> Any; print_xml : Any -> String</code>
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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: <code>fun f (t1->s1;...;tn->sn)
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p1 -> e1 | ... | pn -> en</code> (<code>f</code> is optional) </li>
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<li>Simple function: <code>fun f (p : t) : s = e</code>,
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equivalent to <code>fun f (t -> s) p -> e</code> </li>
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<li>Multiple arguments: <code>fun f (p1 : t1, p2 : t2,...) : s =
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e</code>, equivalent to <code>fun f ((p1,p2,...):(t1,t2,...)) : s
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= e</code> </li>
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</ul>
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</li>
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<li>Types: <code>t -> s</code> </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: <code>(e : t)</code> (forgets any more precise
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type for <code>e</code>) </li>
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<li>Pattern matching: <code>match e with p1 -> e1 | ... | pn ->
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en</code></li>
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<li>Local binding: <code>let p = e1 in e2</code>, equivalent to
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<code>match e1 with p -> e2</code>;
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<code>let p : t = e1 in e2</code> equivalent to
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<code>let p = (e1 : t) in e2</code> </li>
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<li>If-then-else: <code>if e1 then e2 else e3</code>, equivalent to
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<code>match e1 with `true -> e2 | `false -> e3</code></li>
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<li>Exceptions: <ul>
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<li>Raise exception: <code>raise e</code></li>
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<li>Handle exception: <code>try e with p1 -> e1 | ... | pn ->
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en</code></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: <code>&,|,\</code> (<code>|</code> is
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first-match). </li>
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<li>Empty and universal types: <code>Empty,Any</code> or
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<code>_</code>.</li>
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<li>Recursive types and patterns: <code>t where T1 = t2 and ... and
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Tn = tn</code>.</li>
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<li>Capture variable: <code>x</code>. </li>
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<li>Default values: <code>(x := c)</code>. </li>
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</ul>
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</box>
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<box title="References" link="ref">
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<ul>
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<li>Type: <code>ref %%T%%</code>.</li>
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<li>Construction: <code>ref %%T%% %%e%%</code>.</li>
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<li>Dereferencing: <code>!%%e1%%</code>.</li>
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<li>Assignment: <code>%%e1%% := %%e2%%</code>.</li>
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</ul>
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</box>
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<box title="Toplevel statements" link="toplevel">
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<ul>
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<li>Global expression to evaluate.</li>
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<li>Global let-binding.</li>
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<li>Global function declaration.</li>
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<li>Type declarations: <code>type T = t</code>.</li>
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<li>Global <local href="namespaces">namespace</local>:
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<code>namespace p = "..."</code>,
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<code>namespace "..."</code>.</li>
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<li>Source inclusion: <code>include %%filename_string%%</code>.</li>
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<li>Debug directives: <code>debug %%directive argument%%</code> <br/>
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where <code>%%directive%%</code> is one of the following: <code>accept</code>,
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<code>subtype</code>, <code>compile</code>, <code>sample</code>, <code>filter</code>.
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</li>
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<li>Toplevel directives: <code>#env</code>, <code>#quit</code>,
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<code>#reinit_ns</code>.</li>
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</ul>
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</box>
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</page>
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