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diff --git a/doc/tutorial/gf-tutorial2.html b/doc/tutorial/gf-tutorial2.html index 9d82a7f3d..9730526e2 100644 --- a/doc/tutorial/gf-tutorial2.html +++ b/doc/tutorial/gf-tutorial2.html @@ -7,7 +7,7 @@ <P ALIGN="center"><CENTER><H1>Grammatical Framework Tutorial</H1> <FONT SIZE="4"> <I>Author: Aarne Ranta <aarne (at) cs.chalmers.se></I><BR> -Last update: Sat Dec 17 13:32:10 2005 +Last update: Sat Dec 17 21:42:39 2005 </FONT></CENTER> <P></P> @@ -80,20 +80,35 @@ Last update: Sat Dec 17 13:32:10 2005 <LI><A HREF="#toc49">Morphological analysis and morphology quiz</A> <LI><A HREF="#toc50">Discontinuous constituents</A> </UL> - <LI><A HREF="#toc51">Topics still to be written</A> + <LI><A HREF="#toc51">More constructs for concrete syntax</A> <UL> <LI><A HREF="#toc52">Free variation</A> - <LI><A HREF="#toc53">Record extension, tuples</A> - <LI><A HREF="#toc54">Predefined types and operations</A> - <LI><A HREF="#toc55">Lexers and unlexers</A> - <LI><A HREF="#toc56">Grammars of formal languages</A> + <LI><A HREF="#toc53">Record extension and subtyping</A> + <LI><A HREF="#toc54">Tuples and product types</A> + <LI><A HREF="#toc55">Predefined types and operations</A> + </UL> + <LI><A HREF="#toc56">More features of the module system</A> + <UL> <LI><A HREF="#toc57">Resource grammars and their reuse</A> <LI><A HREF="#toc58">Interfaces, instances, and functors</A> - <LI><A HREF="#toc59">Speech input and output</A> - <LI><A HREF="#toc60">Embedded grammars in Haskell, Java, and Prolog</A> - <LI><A HREF="#toc61">Dependent types, variable bindings, semantic definitions</A> - <LI><A HREF="#toc62">Transfer modules</A> - <LI><A HREF="#toc63">Alternative input and output grammar formats</A> + <LI><A HREF="#toc59">Restricted inheritance and qualified opening</A> + </UL> + <LI><A HREF="#toc60">More concepts of abstract syntax</A> + <UL> + <LI><A HREF="#toc61">Dependent types</A> + <LI><A HREF="#toc62">Higher-order abstract syntax</A> + <LI><A HREF="#toc63">Semantic definitions</A> + <LI><A HREF="#toc64">Case study: grammars of formal languages</A> + </UL> + <LI><A HREF="#toc65">Transfer modules</A> + <LI><A HREF="#toc66">Practical issues</A> + <UL> + <LI><A HREF="#toc67">Lexers and unlexers</A> + <LI><A HREF="#toc68">Efficiency of grammars</A> + <LI><A HREF="#toc69">Speech input and output</A> + <LI><A HREF="#toc70">Communicating with GF</A> + <LI><A HREF="#toc71">Embedded grammars in Haskell, Java, and Prolog</A> + <LI><A HREF="#toc72">Alternative input and output grammar formats</A> </UL> </UL> @@ -619,11 +634,7 @@ Examples of records of this type are {s = "foo"} {s = "hello" ++ "world"} </PRE> -<P> -The type <CODE>Str</CODE> is really the type of <B>token lists</B>, but -most of the time one can conveniently think of it as the type of strings, -denoted by string literals in double quotes. -</P> +<P></P> <P> Whenever a record <CODE>r</CODE> of type <CODE>{s : Str}</CODE> is given, <CODE>r.s</CODE> is an object of type <CODE>Str</CODE>. This is @@ -634,6 +645,35 @@ of fields from a record: <LI>if <I>r</I> : <CODE>{</CODE> ... <I>p</I> : <I>T</I> ... <CODE>}</CODE> then <I>r.p</I> : <I>T</I> </UL> +<P> +The type <CODE>Str</CODE> is really the type of <B>token lists</B>, but +most of the time one can conveniently think of it as the type of strings, +denoted by string literals in double quotes. +</P> +<P> +Notice that +</P> +<PRE> + "hello world" +</PRE> +<P> +is not recommended as an expression of type <CODE>Str</CODE>. It denotes +a token with a space in it, and will usually +not work with the lexical analysis that precedes parsing. A shorthand +exemplified by +</P> +<PRE> + ["hello world and people"] === "hello" ++ "world" ++ "and" ++ "people" +</PRE> +<P> +can be used for lists of tokens. The expression +</P> +<PRE> + [] +</PRE> +<P> +denotes the empty token list. +</P> <A NAME="toc18"></A> <H3>An abstract syntax example</H3> <P> @@ -1498,28 +1538,33 @@ the formation of noun phrases and verb phrases. <A NAME="toc47"></A> <H3>English concrete syntax with parameters</H3> <PRE> - concrete PaleolithicEng of Paleolithic = open MorphoEng in { + concrete PaleolithicEng of Paleolithic = open Prelude, MorphoEng in { lincat - S, A = {s : Str} ; + S, A = SS ; VP, CN, V, TV = {s : Number => Str} ; NP = {s : Str ; n : Number} ; lin - PredVP np vp = {s = np.s ++ vp.s ! np.n} ; + PredVP np vp = ss (np.s ++ vp.s ! np.n) ; UseV v = v ; ComplTV tv np = {s = \\n => tv.s ! n ++ np.s} ; - UseA a = {s = \\n => case n of {Sg => "is" ; Pl => "are"} ++ a.s} ; - This cn = {s = "this" ++ cn.s ! Sg } ; - Indef cn = {s = "a" ++ cn.s ! Sg} ; - All cn = {s = "all" ++ cn.s ! Pl} ; - Two cn = {s = "two" ++ cn.s ! Pl} ; + UseA a = {s = \\n => case n of {Sg => "is" ; Pl => "are"} ++ a.s} ; + This = det Sg "this" ; + Indef = det Sg "a" ; + All = det Pl "all" ; + Two = det Pl "two" ; ModA a cn = {s = \\n => a.s ++ cn.s ! n} ; Louse = mkNoun "louse" "lice" ; Snake = regNoun "snake" ; - Green = {s = "green"} ; - Warm = {s = "warm"} ; + Green = ss "green" ; + Warm = ss "warm" ; Laugh = regVerb "laugh" ; Sleep = regVerb "sleep" ; Kill = regVerb "kill" ; + oper + det : Number -> Str -> Noun -> {s : Str ; n : Number} = \n,d,cn -> { + s = d ++ n.s ! n ; + n = n + } ; } </PRE> <P></P> @@ -1527,19 +1572,19 @@ the formation of noun phrases and verb phrases. <H3>Hierarchic parameter types</H3> <P> The reader familiar with a functional programming language such as -<a href="<A HREF="http://www.haskell.org">http://www.haskell.org</A>">Haskell<a> must have noticed the similarity -between parameter types in GF and algebraic datatypes (<CODE>data</CODE> definitions +<A HREF="http://www.haskell.org">Haskell</A> must have noticed the similarity +between parameter types in GF and <B>algebraic datatypes</B> (<CODE>data</CODE> definitions in Haskell). The GF parameter types are actually a special case of algebraic datatypes: the main restriction is that in GF, these types must be finite. -(This restriction makes it possible to invert linearization rules into +(It is this restriction that makes it possible to invert linearization rules into parsing methods.) </P> <P> However, finite is not the same thing as enumerated. Even in GF, parameter constructors can take arguments, provided these arguments are from other -parameter types (recursion is forbidden). Such parameter types impose a -hierarchic order among parameters. They are often useful to define -linguistically accurate parameter systems. +parameter types - only recursion is forbidden. Such parameter types impose a +hierarchic order among parameters. They are often needed to define +the linguistically most accurate parameter systems. </P> <P> To give an example, Swedish adjectives @@ -1603,7 +1648,7 @@ file for later use, by the command <CODE>morpho_list = ml</CODE> > morpho_list -number=25 -cat=V </PRE> <P> -The number flag gives the number of exercises generated. +The <CODE>number</CODE> flag gives the number of exercises generated. </P> <A NAME="toc50"></A> <H3>Discontinuous constituents</H3> @@ -1615,7 +1660,7 @@ a sentence may place the object between the verb and the particle: <I>he switched it off</I>. </P> <P> -The first of the following judgements defines transitive verbs as a +The first of the following judgements defines transitive verbs as <B>discontinuous constituents</B>, i.e. as having a linearization type with two strings and not just one. The second judgement shows how the constituents are separated by the object in complementization. @@ -1624,37 +1669,145 @@ shows how the constituents are separated by the object in complementization. lincat TV = {s : Number => Str ; s2 : Str} ; lin ComplTV tv obj = {s = \\n => tv.s ! n ++ obj.s ++ tv.s2} ; </PRE> -<P></P> <P> -GF currently requires that all fields in linearization records that -have a table with value type <CODE>Str</CODE> have as labels -either <CODE>s</CODE> or <CODE>s</CODE> with an integer index. +There is no restriction in the number of discontinuous constituents +(or other fields) a <CODE>lincat</CODE> may contain. The only condition is that +the fields must be of finite types, i.e. built from records, tables, +parameters, and <CODE>Str</CODE>, and not functions. A mathematical result +about parsing in GF says that the worst-case complexity of parsing +increases with the number of discontinuous constituents. Moreover, +the parsing and linearization commands only give reliable results +for categories whose linearization type has a unique <CODE>Str</CODE> valued +field labelled <CODE>s</CODE>. </P> <A NAME="toc51"></A> -<H2>Topics still to be written</H2> +<H2>More constructs for concrete syntax</H2> <A NAME="toc52"></A> <H3>Free variation</H3> +<P> +Sometimes there are many alternative ways to define a concrete syntax. +For instance, the verb negation in English can be expressed both by +<I>does not</I> and <I>doesn't</I>. In linguistic terms, these expressions +are in <B>free variation</B>. The <CODE>variants</CODE> construct of GF can +be used to give a list of strings in free variation. For example, +</P> +<PRE> + NegVerb verb = {s = variants {["does not"] ; "doesn't} ++ verb.s} ; +</PRE> +<P> +An empty variant list +</P> +<PRE> + variants {} +</PRE> +<P> +can be used e.g. if a word lacks a certain form. +</P> +<P> +In general, <CODE>variants</CODE> should be used cautiously. It is not +recommended for modules aimed to be libraries, because the +user of the library has no way to choose among the variants. +Moreover, even though <CODE>variants</CODE> admits lists of any type, +its semantics for complex types can cause surprises. +</P> <A NAME="toc53"></A> -<H3>Record extension, tuples</H3> +<H3>Record extension and subtyping</H3> +<P> +Record types and records can be <B>extended</B> with new fields. For instance, +in German it is natural to see transitive verbs as verbs with a case. +The symbol <CODE>**</CODE> is used for both constructs. +</P> +<PRE> + lincat TV = Verb ** {c : Case} ; + + lin Follow = regVerb "folgen" ** {c = Dative} ; +</PRE> +<P> +To extend a record type or a record with a field whose label it +already has is a type error. +</P> +<P> +A record type <I>T</I> is a <B>subtype</B> of another one <I>R</I>, if <I>T</I> has +all the fields of <I>R</I> and possibly other fields. For instance, +an extension of a record type is always a subtype of it. +</P> +<P> +If <I>T</I> is a subtype of <I>R</I>, an object of <I>T</I> can be used whenever +an object of <I>R</I> is required. For instance, a transitive verb can +be used whenever a verb is required. +</P> +<P> +<B>Contravariance</B> means that a function taking an <I>R</I> as argument +can also be applied to any object of a subtype <I>T</I>. +</P> <A NAME="toc54"></A> -<H3>Predefined types and operations</H3> +<H3>Tuples and product types</H3> +<P> +Product types and tuples are syntactic sugar for record types and records: +</P> +<PRE> + T1 * ... * Tn === {p1 : T1 ; ... ; pn : Tn} + <t1, ..., tn> === {p1 = T1 ; ... ; pn = Tn} +</PRE> +<P> +Thus the labels <CODE>p1, p2,...`</CODE> are hard-coded. +</P> <A NAME="toc55"></A> -<H3>Lexers and unlexers</H3> +<H3>Predefined types and operations</H3> +<P> +GF has the following predefined categories in abstract syntax: +</P> +<PRE> + cat Int ; -- integers, e.g. 0, 5, 743145151019 + cat Float ; -- floats, e.g. 0.0, 3.1415926 + cat String ; -- strings, e.g. "", "foo", "123" +</PRE> +<P> +The objects of each of these categories are <B>literals</B> +as indicated in the comments above. No <CODE>fun</CODE> definition +can have a predefined category as its value type, but +they can be used as arguments. For example: +</P> +<PRE> + fun StreetAddress : Int -> String -> Address ; + lin StreetAddress number street = {s = number.s ++ street.s} ; + + -- e.g. (StreetAddress 10 "Downing Street") : Address +</PRE> +<P></P> <A NAME="toc56"></A> -<H3>Grammars of formal languages</H3> +<H2>More features of the module system</H2> <A NAME="toc57"></A> <H3>Resource grammars and their reuse</H3> <A NAME="toc58"></A> <H3>Interfaces, instances, and functors</H3> <A NAME="toc59"></A> -<H3>Speech input and output</H3> +<H3>Restricted inheritance and qualified opening</H3> <A NAME="toc60"></A> -<H3>Embedded grammars in Haskell, Java, and Prolog</H3> +<H2>More concepts of abstract syntax</H2> <A NAME="toc61"></A> -<H3>Dependent types, variable bindings, semantic definitions</H3> +<H3>Dependent types</H3> <A NAME="toc62"></A> -<H3>Transfer modules</H3> +<H3>Higher-order abstract syntax</H3> <A NAME="toc63"></A> +<H3>Semantic definitions</H3> +<A NAME="toc64"></A> +<H3>Case study: grammars of formal languages</H3> +<A NAME="toc65"></A> +<H2>Transfer modules</H2> +<A NAME="toc66"></A> +<H2>Practical issues</H2> +<A NAME="toc67"></A> +<H3>Lexers and unlexers</H3> +<A NAME="toc68"></A> +<H3>Efficiency of grammars</H3> +<A NAME="toc69"></A> +<H3>Speech input and output</H3> +<A NAME="toc70"></A> +<H3>Communicating with GF</H3> +<A NAME="toc71"></A> +<H3>Embedded grammars in Haskell, Java, and Prolog</H3> +<A NAME="toc72"></A> <H3>Alternative input and output grammar formats</H3> <!-- html code generated by txt2tags 2.3 (http://txt2tags.sf.net) --> |