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| author | aarne <aarne@chalmers.se> | 2010-12-22 14:11:55 +0000 |
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| committer | aarne <aarne@chalmers.se> | 2010-12-22 14:11:55 +0000 |
| commit | c5b963769539c8a7c9bd154585686d263c7d6d8a (patch) | |
| tree | c1bc4129d94e51c5e68ed4b7c1888ae120aac3fd /deprecated/Resource-HOWTO.html | |
| parent | ce15ec7b787479ca4c7295863ea7fa5cfdd16755 (diff) | |
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diff --git a/deprecated/Resource-HOWTO.html b/deprecated/Resource-HOWTO.html deleted file mode 100644 index ce2c15137..000000000 --- a/deprecated/Resource-HOWTO.html +++ /dev/null @@ -1,967 +0,0 @@ -<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> -<HTML> -<HEAD> -<META NAME="generator" CONTENT="http://txt2tags.sf.net"> -<TITLE>Resource grammar writing HOWTO</TITLE> -</HEAD><BODY BGCOLOR="white" TEXT="black"> -<P ALIGN="center"><CENTER><H1>Resource grammar writing HOWTO</H1> -<FONT SIZE="4"> -<I>Author: Aarne Ranta <aarne (at) cs.chalmers.se></I><BR> -Last update: Mon Sep 22 14:28:01 2008 -</FONT></CENTER> - -<P></P> -<HR NOSHADE SIZE=1> -<P></P> - <UL> - <LI><A HREF="#toc1">The resource grammar structure</A> - <UL> - <LI><A HREF="#toc2">Library API modules</A> - <LI><A HREF="#toc3">Phrase category modules</A> - <LI><A HREF="#toc4">Infrastructure modules</A> - <LI><A HREF="#toc5">Lexical modules</A> - </UL> - <LI><A HREF="#toc6">Language-dependent syntax modules</A> - <UL> - <LI><A HREF="#toc7">The present-tense fragment</A> - </UL> - <LI><A HREF="#toc8">Phases of the work</A> - <UL> - <LI><A HREF="#toc9">Putting up a directory</A> - <LI><A HREF="#toc10">Direction of work</A> - <LI><A HREF="#toc11">The develop-test cycle</A> - <LI><A HREF="#toc12">Auxiliary modules</A> - <LI><A HREF="#toc13">Morphology and lexicon</A> - <LI><A HREF="#toc14">Lock fields</A> - <LI><A HREF="#toc15">Lexicon construction</A> - </UL> - <LI><A HREF="#toc16">Lexicon extension</A> - <UL> - <LI><A HREF="#toc17">The irregularity lexicon</A> - <LI><A HREF="#toc18">Lexicon extraction from a word list</A> - <LI><A HREF="#toc19">Lexicon extraction from raw text data</A> - <LI><A HREF="#toc20">Bootstrapping with smart paradigms</A> - </UL> - <LI><A HREF="#toc21">Extending the resource grammar API</A> - <LI><A HREF="#toc22">Using parametrized modules</A> - <UL> - <LI><A HREF="#toc23">Writing an instance of parametrized resource grammar implementation</A> - <LI><A HREF="#toc24">Parametrizing a resource grammar implementation</A> - </UL> - <LI><A HREF="#toc25">Character encoding and transliterations</A> - <LI><A HREF="#toc26">Coding conventions in GF</A> - <LI><A HREF="#toc27">Transliterations</A> - </UL> - -<P></P> -<HR NOSHADE SIZE=1> -<P></P> -<P> -<B>History</B> -</P> -<P> -September 2008: updated for Version 1.5. -</P> -<P> -October 2007: updated for Version 1.2. -</P> -<P> -January 2006: first version. -</P> -<P> -The purpose of this document is to tell how to implement the GF -resource grammar API for a new language. We will <I>not</I> cover how -to use the resource grammar, nor how to change the API. But we -will give some hints how to extend the API. -</P> -<P> -A manual for using the resource grammar is found in -</P> -<P> -<A HREF="../lib/resource/doc/synopsis.html"><CODE>www.cs.chalmers.se/Cs/Research/Language-technology/GF/lib/resource/doc/synopsis.html</CODE></A>. -</P> -<P> -A tutorial on GF, also introducing the idea of resource grammars, is found in -</P> -<P> -<A HREF="./gf-tutorial.html"><CODE>www.cs.chalmers.se/Cs/Research/Language-technology/GF/doc/gf-tutorial.html</CODE></A>. -</P> -<P> -This document concerns the API v. 1.5, while the current stable release is 1.4. -You can find the code for the stable release in -</P> -<P> -<A HREF="../lib/resource"><CODE>www.cs.chalmers.se/Cs/Research/Language-technology/GF/lib/resource/</CODE></A> -</P> -<P> -and the next release in -</P> -<P> -<A HREF="../next-lib/src"><CODE>www.cs.chalmers.se/Cs/Research/Language-technology/GF/next-lib/src/</CODE></A> -</P> -<P> -It is recommended to build new grammars to match the next release. -</P> -<A NAME="toc1"></A> -<H2>The resource grammar structure</H2> -<P> -The library is divided into a bunch of modules, whose dependencies -are given in the following figure. -</P> -<P> -<IMG ALIGN="left" SRC="Syntax.png" BORDER="0" ALT=""> -</P> -<P> -Modules of different kinds are distinguished as follows: -</P> -<UL> -<LI>solid contours: module seen by end users -<LI>dashed contours: internal module -<LI>ellipse: abstract/concrete pair of modules -<LI>rectangle: resource or instance -<LI>diamond: interface -</UL> - -<P> -Put in another way: -</P> -<UL> -<LI>solid rectangles and diamonds: user-accessible library API -<LI>solid ellipses: user-accessible top-level grammar for parsing and linearization -<LI>dashed contours: not visible to users -</UL> - -<P> -The dashed ellipses form the main parts of the implementation, on which the resource -grammar programmer has to work with. She also has to work on the <CODE>Paradigms</CODE> -module. The rest of the modules can be produced mechanically from corresponding -modules for other languages, by just changing the language codes appearing in -their module headers. -</P> -<P> -The module structure is rather flat: most modules are direct -parents of <CODE>Grammar</CODE>. The idea -is that the implementors can concentrate on one linguistic aspect at a time, or -also distribute the work among several authors. The module <CODE>Cat</CODE> -defines the "glue" that ties the aspects together - a type system -to which all the other modules conform, so that e.g. <CODE>NP</CODE> means -the same thing in those modules that use <CODE>NP</CODE>s and those that -constructs them. -</P> -<A NAME="toc2"></A> -<H3>Library API modules</H3> -<P> -For the user of the library, these modules are the most important ones. -In a typical application, it is enough to open <CODE>Paradigms</CODE> and <CODE>Syntax</CODE>. -The module <CODE>Try</CODE> combines these two, making it possible to experiment -with combinations of syntactic and lexical constructors by using the -<CODE>cc</CODE> command in the GF shell. Here are short explanations of each API module: -</P> -<UL> -<LI><CODE>Try</CODE>: the whole resource library for a language (<CODE>Paradigms</CODE>, <CODE>Syntax</CODE>, - <CODE>Irreg</CODE>, and <CODE>Extra</CODE>); - produced mechanically as a collection of modules -<LI><CODE>Syntax</CODE>: language-independent categories, syntax functions, and structural words; - produced mechanically as a collection of modules -<LI><CODE>Constructors</CODE>: language-independent syntax functions and structural words; - produced mechanically via functor instantiation -<LI><CODE>Paradigms</CODE>: language-dependent morphological paradigms -</UL> - -<A NAME="toc3"></A> -<H3>Phrase category modules</H3> -<P> -The immediate parents of <CODE>Grammar</CODE> will be called <B>phrase category modules</B>, -since each of them concentrates on a particular phrase category (nouns, verbs, -adjectives, sentences,...). A phrase category module tells -<I>how to construct phrases in that category</I>. You will find out that -all functions in any of these modules have the same value type (or maybe -one of a small number of different types). Thus we have -</P> -<UL> -<LI><CODE>Noun</CODE>: construction of nouns and noun phrases -<LI><CODE>Adjective</CODE>: construction of adjectival phrases -<LI><CODE>Verb</CODE>: construction of verb phrases -<LI><CODE>Adverb</CODE>: construction of adverbial phrases -<LI><CODE>Numeral</CODE>: construction of cardinal and ordinal numerals -<LI><CODE>Sentence</CODE>: construction of sentences and imperatives -<LI><CODE>Question</CODE>: construction of questions -<LI><CODE>Relative</CODE>: construction of relative clauses -<LI><CODE>Conjunction</CODE>: coordination of phrases -<LI><CODE>Phrase</CODE>: construction of the major units of text and speech -<LI><CODE>Text</CODE>: construction of texts as sequences of phrases -<LI><CODE>Idiom</CODE>: idiomatic expressions such as existentials -</UL> - -<A NAME="toc4"></A> -<H3>Infrastructure modules</H3> -<P> -Expressions of each phrase category are constructed in the corresponding -phrase category module. But their <I>use</I> takes mostly place in other modules. -For instance, noun phrases, which are constructed in <CODE>Noun</CODE>, are -used as arguments of functions of almost all other phrase category modules. -How can we build all these modules independently of each other? -</P> -<P> -As usual in typeful programming, the <I>only</I> thing you need to know -about an object you use is its type. When writing a linearization rule -for a GF abstract syntax function, the only thing you need to know is -the linearization types of its value and argument categories. To achieve -the division of the resource grammar to several parallel phrase category modules, -what we need is an underlying definition of the linearization types. This -definition is given as the implementation of -</P> -<UL> -<LI><CODE>Cat</CODE>: syntactic categories of the resource grammar -</UL> - -<P> -Any resource grammar implementation has first to agree on how to implement -<CODE>Cat</CODE>. Luckily enough, even this can be done incrementally: you -can skip the <CODE>lincat</CODE> definition of a category and use the default -<CODE>{s : Str}</CODE> until you need to change it to something else. In -English, for instance, many categories do have this linearization type. -</P> -<A NAME="toc5"></A> -<H3>Lexical modules</H3> -<P> -What is lexical and what is syntactic is not as clearcut in GF as in -some other grammar formalisms. Logically, lexical means atom, i.e. a -<CODE>fun</CODE> with no arguments. Linguistically, one may add to this -that the <CODE>lin</CODE> consists of only one token (or of a table whose values -are single tokens). Even in the restricted lexicon included in the resource -API, the latter rule is sometimes violated in some languages. For instance, -<CODE>Structural.both7and_DConj</CODE> is an atom, but its linearization is -two words e.g. <I>both - and</I>. -</P> -<P> -Another characterization of lexical is that lexical units can be added -almost <I>ad libitum</I>, and they cannot be defined in terms of already -given rules. The lexical modules of the resource API are thus more like -samples than complete lists. There are two such modules: -</P> -<UL> -<LI><CODE>Structural</CODE>: structural words (determiners, conjunctions,...) -<LI><CODE>Lexicon</CODE>: basic everyday content words (nouns, verbs,...) -</UL> - -<P> -The module <CODE>Structural</CODE> aims for completeness, and is likely to -be extended in future releases of the resource. The module <CODE>Lexicon</CODE> -gives a "random" list of words, which enables testing the syntax. -It also provides a check list for morphology, since those words are likely to include -most morphological patterns of the language. -</P> -<P> -In the case of <CODE>Lexicon</CODE> it may come out clearer than anywhere else -in the API that it is impossible to give exact translation equivalents in -different languages on the level of a resource grammar. This is no problem, -since application grammars can use the resource in different ways for -different languages. -</P> -<A NAME="toc6"></A> -<H2>Language-dependent syntax modules</H2> -<P> -In addition to the common API, there is room for language-dependent extensions -of the resource. The top level of each languages looks as follows (with German -as example): -</P> -<PRE> - abstract AllGerAbs = Lang, ExtraGerAbs, IrregGerAbs -</PRE> -<P> -where <CODE>ExtraGerAbs</CODE> is a collection of syntactic structures specific to German, -and <CODE>IrregGerAbs</CODE> is a dictionary of irregular words of German -(at the moment, just verbs). Each of these language-specific grammars has -the potential to grow into a full-scale grammar of the language. These grammar -can also be used as libraries, but the possibility of using functors is lost. -</P> -<P> -To give a better overview of language-specific structures, -modules like <CODE>ExtraGerAbs</CODE> -are built from a language-independent module <CODE>ExtraAbs</CODE> -by restricted inheritance: -</P> -<PRE> - abstract ExtraGerAbs = Extra [f,g,...] -</PRE> -<P> -Thus any category and function in <CODE>Extra</CODE> may be shared by a subset of all -languages. One can see this set-up as a matrix, which tells -what <CODE>Extra</CODE> structures -are implemented in what languages. For the common API in <CODE>Grammar</CODE>, the matrix -is filled with 1's (everything is implemented in every language). -</P> -<P> -In a minimal resource grammar implementation, the language-dependent -extensions are just empty modules, but it is good to provide them for -the sake of uniformity. -</P> -<A NAME="toc7"></A> -<H3>The present-tense fragment</H3> -<P> -Some lines in the resource library are suffixed with the comment -</P> -<PRE> - --# notpresent -</PRE> -<P> -which is used by a preprocessor to exclude those lines from -a reduced version of the full resource. This present-tense-only -version is useful for applications in most technical text, since -they reduce the grammar size and compilation time. It can also -be useful to exclude those lines in a first version of resource -implementation. To compile a grammar with present-tense-only, use -</P> -<PRE> - make Present -</PRE> -<P> -with <CODE>resource/Makefile</CODE>. -</P> -<A NAME="toc8"></A> -<H2>Phases of the work</H2> -<A NAME="toc9"></A> -<H3>Putting up a directory</H3> -<P> -Unless you are writing an instance of a parametrized implementation -(Romance or Scandinavian), which will be covered later, the -simplest way is to follow roughly the following procedure. Assume you -are building a grammar for the German language. Here are the first steps, -which we actually followed ourselves when building the German implementation -of resource v. 1.0 at Ubuntu linux. We have slightly modified them to -match resource v. 1.5 and GF v. 3.0. -</P> -<OL> -<LI>Create a sister directory for <CODE>GF/lib/resource/english</CODE>, named - <CODE>german</CODE>. -<PRE> - cd GF/lib/resource/ - mkdir german - cd german -</PRE> -<P></P> -<LI>Check out the [ISO 639 3-letter language code - <A HREF="http://www.w3.org/WAI/ER/IG/ert/iso639.htm">http://www.w3.org/WAI/ER/IG/ert/iso639.htm</A>] - for German: both <CODE>Ger</CODE> and <CODE>Deu</CODE> are given, and we pick <CODE>Ger</CODE>. - (We use the 3-letter codes rather than the more common 2-letter codes, - since they will suffice for many more languages!) -<P></P> -<LI>Copy the <CODE>*Eng.gf</CODE> files from <CODE>english</CODE> <CODE>german</CODE>, - and rename them: -<PRE> - cp ../english/*Eng.gf . - rename 's/Eng/Ger/' *Eng.gf -</PRE> - If you don't have the <CODE>rename</CODE> command, you can use a bash script with <CODE>mv</CODE>. -</OL> - -<OL> -<LI>Change the <CODE>Eng</CODE> module references to <CODE>Ger</CODE> references - in all files: -<PRE> - sed -i 's/English/German/g' *Ger.gf - sed -i 's/Eng/Ger/g' *Ger.gf -</PRE> - The first line prevents changing the word <CODE>English</CODE>, which appears - here and there in comments, to <CODE>Gerlish</CODE>. The <CODE>sed</CODE> command syntax - may vary depending on your operating system. -<P></P> -<LI>This may of course change unwanted occurrences of the - string <CODE>Eng</CODE> - verify this by -<PRE> - grep Ger *.gf -</PRE> - But you will have to make lots of manual changes in all files anyway! -<P></P> -<LI>Comment out the contents of these files: -<PRE> - sed -i 's/^/--/' *Ger.gf -</PRE> - This will give you a set of templates out of which the grammar - will grow as you uncomment and modify the files rule by rule. -<P></P> -<LI>In all <CODE>.gf</CODE> files, uncomment the module headers and brackets, - leaving the module bodies commented. Unfortunately, there is no - simple way to do this automatically (or to avoid commenting these - lines in the previous step) - but uncommenting the first - and the last lines will actually do the job for many of the files. -<P></P> -<LI>Uncomment the contents of the main grammar file: -<PRE> - sed -i 's/^--//' LangGer.gf -</PRE> -<P></P> -<LI>Now you can open the grammar <CODE>LangGer</CODE> in GF: -<PRE> - gf LangGer.gf -</PRE> - You will get lots of warnings on missing rules, but the grammar will compile. -<P></P> -<LI>At all the following steps you will now have a valid, but incomplete - GF grammar. The GF command -<PRE> - pg -missing -</PRE> - tells you what exactly is missing. -</OL> - -<P> -Here is the module structure of <CODE>LangGer</CODE>. It has been simplified by leaving out -the majority of the phrase category modules. Each of them has the same dependencies -as <CODE>VerbGer</CODE>, whose complete dependencies are shown as an example. -</P> -<P> -<IMG ALIGN="middle" SRC="German.png" BORDER="0" ALT=""> -</P> -<A NAME="toc10"></A> -<H3>Direction of work</H3> -<P> -The real work starts now. There are many ways to proceed, the most obvious ones being -</P> -<UL> -<LI>Top-down: start from the module <CODE>Phrase</CODE> and go down to <CODE>Sentence</CODE>, then - <CODE>Verb</CODE>, <CODE>Noun</CODE>, and in the end <CODE>Lexicon</CODE>. In this way, you are all the time - building complete phrases, and add them with more content as you proceed. - <B>This approach is not recommended</B>. It is impossible to test the rules if - you have no words to apply the constructions to. -<P></P> -<LI>Bottom-up: set as your first goal to implement <CODE>Lexicon</CODE>. To this end, you - need to write <CODE>ParadigmsGer</CODE>, which in turn needs parts of - <CODE>MorphoGer</CODE> and <CODE>ResGer</CODE>. - <B>This approach is not recommended</B>. You can get stuck to details of - morphology such as irregular words, and you don't have enough grasp about - the type system to decide what forms to cover in morphology. -</UL> - -<P> -The practical working direction is thus a saw-like motion between the morphological -and top-level modules. Here is a possible course of the work that gives enough -test data and enough general view at any point: -</P> -<OL> -<LI>Define <CODE>Cat.N</CODE> and the required parameter types in <CODE>ResGer</CODE>. As we define -<PRE> - lincat N = {s : Number => Case => Str ; g : Gender} ; -</PRE> -we need the parameter types <CODE>Number</CODE>, <CODE>Case</CODE>, and <CODE>Gender</CODE>. The definition -of <CODE>Number</CODE> in <A HREF="../lib/resource/common/ParamX.gf"><CODE>common/ParamX</CODE></A> -works for German, so we -use it and just define <CODE>Case</CODE> and <CODE>Gender</CODE> in <CODE>ResGer</CODE>. -<P></P> -<LI>Define some cases of <CODE>mkN</CODE> in <CODE>ParadigmsGer</CODE>. In this way you can -already implement a huge amount of nouns correctly in <CODE>LexiconGer</CODE>. Actually -just adding the worst-case instance of <CODE>mkN</CODE> (the one taking the most -arguments) should suffice for every noun - but, -since it is tedious to use, you -might proceed to the next step before returning to morphology and defining the -real work horse, <CODE>mkN</CODE> taking two forms and a gender. -<P></P> -<LI>While doing this, you may want to test the resource independently. Do this by - starting the GF shell in the <CODE>resource</CODE> directory, by the commands -<PRE> - > i -retain german/ParadigmsGer - > cc -table mkN "Kirche" -</PRE> -<P></P> -<LI>Proceed to determiners and pronouns in -<CODE>NounGer</CODE> (<CODE>DetCN UsePron DetQuant NumSg DefArt IndefArt UseN</CODE>) and -<CODE>StructuralGer</CODE> (<CODE>i_Pron this_Quant</CODE>). You also need some categories and -parameter types. At this point, it is maybe not possible to find out the final -linearization types of <CODE>CN</CODE>, <CODE>NP</CODE>, <CODE>Det</CODE>, and <CODE>Quant</CODE>, but at least you should -be able to correctly inflect noun phrases such as <I>every airplane</I>: -<PRE> - > i german/LangGer.gf - > l -table DetCN every_Det (UseN airplane_N) - - Nom: jeder Flugzeug - Acc: jeden Flugzeug - Dat: jedem Flugzeug - Gen: jedes Flugzeugs -</PRE> -<P></P> -<LI>Proceed to verbs: define <CODE>CatGer.V</CODE>, <CODE>ResGer.VForm</CODE>, and -<CODE>ParadigmsGer.mkV</CODE>. You may choose to exclude <CODE>notpresent</CODE> -cases at this point. But anyway, you will be able to inflect a good -number of verbs in <CODE>Lexicon</CODE>, such as -<CODE>live_V</CODE> (<CODE>mkV "leben"</CODE>). -<P></P> -<LI>Now you can soon form your first sentences: define <CODE>VP</CODE> and -<CODE>Cl</CODE> in <CODE>CatGer</CODE>, <CODE>VerbGer.UseV</CODE>, and <CODE>SentenceGer.PredVP</CODE>. -Even if you have excluded the tenses, you will be able to produce -<PRE> - > i -preproc=./mkPresent german/LangGer.gf - > l -table PredVP (UsePron i_Pron) (UseV live_V) - - Pres Simul Pos Main: ich lebe - Pres Simul Pos Inv: lebe ich - Pres Simul Pos Sub: ich lebe - Pres Simul Neg Main: ich lebe nicht - Pres Simul Neg Inv: lebe ich nicht - Pres Simul Neg Sub: ich nicht lebe -</PRE> -You should also be able to parse: -<PRE> - > p -cat=Cl "ich lebe" - PredVP (UsePron i_Pron) (UseV live_V) -</PRE> -<P></P> -<LI>Transitive verbs -(<CODE>CatGer.V2 CatGer.VPSlash ParadigmsGer.mkV2 VerbGer.ComplSlash VerbGer.SlashV2a</CODE>) -are a natural next step, so that you can -produce <CODE>ich liebe dich</CODE> ("I love you"). -<P></P> -<LI>Adjectives (<CODE>CatGer.A ParadigmsGer.mkA NounGer.AdjCN AdjectiveGer.PositA</CODE>) -will force you to think about strong and weak declensions, so that you can -correctly inflect <I>mein neuer Wagen, dieser neue Wagen</I> -("my new car, this new car"). -<P></P> -<LI>Once you have implemented the set -(``Noun.DetCN Noun.AdjCN Verb.UseV Verb.ComplSlash Verb.SlashV2a Sentence.PredVP), -you have overcome most of difficulties. You know roughly what parameters -and dependences there are in your language, and you can now proceed very -much in the order you please. -</OL> - -<A NAME="toc11"></A> -<H3>The develop-test cycle</H3> -<P> -The following develop-test cycle will -be applied most of the time, both in the first steps described above -and in later steps where you are more on your own. -</P> -<OL> -<LI>Select a phrase category module, e.g. <CODE>NounGer</CODE>, and uncomment some - linearization rules (for instance, <CODE>DetCN</CODE>, as above). -<P></P> -<LI>Write down some German examples of this rule, for instance translations - of "the dog", "the house", "the big house", etc. Write these in all their - different forms (two numbers and four cases). -<P></P> -<LI>Think about the categories involved (<CODE>CN, NP, N, Det</CODE>) and the - variations they have. Encode this in the lincats of <CODE>CatGer</CODE>. - You may have to define some new parameter types in <CODE>ResGer</CODE>. -<P></P> -<LI>To be able to test the construction, - define some words you need to instantiate it - in <CODE>LexiconGer</CODE>. You will also need some regular inflection patterns - in<CODE>ParadigmsGer</CODE>. -<P></P> -<LI>Test by parsing, linearization, - and random generation. In particular, linearization to a table should - be used so that you see all forms produced; the <CODE>treebank</CODE> option - preserves the tree -<PRE> - > gr -cat=NP -number=20 | l -table -treebank -</PRE> -<P></P> -<LI>Save some tree-linearization pairs for later regression testing. You can save - a gold standard treebank and use the Unix <CODE>diff</CODE> command to compare later - linearizations produced from the same list of trees. If you save the trees - in a file <CODE>trees</CODE>, you can do as follows: -<PRE> - > rf -file=trees -tree -lines | l -table -treebank | wf -file=treebank -</PRE> -<P></P> -<LI>A file with trees testing all resource functions is included in the resource, - entitled <CODE>resource/exx-resource.gft</CODE>. A treebank can be created from this by - the Unix command -<PRE> - % runghc Make.hs test langs=Ger -</PRE> -</OL> - -<P> -You are likely to run this cycle a few times for each linearization rule -you implement, and some hundreds of times altogether. There are roughly -70 <CODE>cat</CODE>s and -600 <CODE>funs</CODE> in <CODE>Lang</CODE> at the moment; 170 of the <CODE>funs</CODE> are outside the two -lexicon modules). -</P> -<A NAME="toc12"></A> -<H3>Auxiliary modules</H3> -<P> -These auxuliary <CODE>resource</CODE> modules will be written by you. -</P> -<UL> -<LI><CODE>ResGer</CODE>: parameter types and auxiliary operations -(a resource for the resource grammar!) -<LI><CODE>ParadigmsGer</CODE>: complete inflection engine and most important regular paradigms -<LI><CODE>MorphoGer</CODE>: auxiliaries for <CODE>ParadigmsGer</CODE> and <CODE>StructuralGer</CODE>. This need -not be separate from <CODE>ResGer</CODE>. -</UL> - -<P> -These modules are language-independent and provided by the existing resource -package. -</P> -<UL> -<LI><CODE>ParamX</CODE>: parameter types used in many languages -<LI><CODE>CommonX</CODE>: implementation of language-uniform categories - such as $Text$ and $Phr$, as well as of - the logical tense, anteriority, and polarity parameters -<LI><CODE>Coordination</CODE>: operations to deal with lists and coordination -<LI><CODE>Prelude</CODE>: general-purpose operations on strings, records, - truth values, etc. -<LI><CODE>Predef</CODE>: general-purpose operations with hard-coded definitions -</UL> - -<P> -An important decision is what rules to implement in terms of operations in -<CODE>ResGer</CODE>. The <B>golden rule of functional programming</B> says: -</P> -<UL> -<LI><I>Whenever you find yourself programming by copy and paste, write a function instead!</I>. -</UL> - -<P> -This rule suggests that an operation should be created if it is to be -used at least twice. At the same time, a sound principle of <B>vicinity</B> says: -</P> -<UL> -<LI><I>It should not require too much browsing to understand what a piece of code does.</I> -</UL> - -<P> -From these two principles, we have derived the following practice: -</P> -<UL> -<LI>If an operation is needed <I>in two different modules</I>, - it should be created in as an <CODE>oper</CODE> in <CODE>ResGer</CODE>. An example is <CODE>mkClause</CODE>, - used in <CODE>Sentence</CODE>, <CODE>Question</CODE>, and <CODE>Relative</CODE>- -<LI>If an operation is needed <I>twice in the same module</I>, but never - outside, it should be created in the same module. Many examples are - found in <CODE>Numerals</CODE>. -<LI>If an operation is needed <I>twice in the same judgement</I>, but never - outside, it should be created by a <CODE>let</CODE> definition. -<LI>If an operation is only needed once, it should not be created as an <CODE>oper</CODE>, - but rather inlined. However, a <CODE>let</CODE> definition may well be in place just - to make the readable. - Most functions in phrase category modules - are implemented in this way. -</UL> - -<P> -This discipline is very different from the one followed in early -versions of the library (up to 0.9). We then valued the principle of -abstraction more than vicinity, creating layers of abstraction for -almost everything. This led in practice to the duplication of almost -all code on the <CODE>lin</CODE> and <CODE>oper</CODE> levels, and made the code -hard to understand and maintain. -</P> -<A NAME="toc13"></A> -<H3>Morphology and lexicon</H3> -<P> -The paradigms needed to implement -<CODE>LexiconGer</CODE> are defined in -<CODE>ParadigmsGer</CODE>. -This module provides high-level ways to define the linearization of -lexical items, of categories <CODE>N, A, V</CODE> and their complement-taking -variants. -</P> -<P> -For ease of use, the <CODE>Paradigms</CODE> modules follow a certain -naming convention. Thus they for each lexical category, such as <CODE>N</CODE>, -the overloaded functions, such as <CODE>mkN</CODE>, with the following cases: -</P> -<UL> -<LI>the worst-case construction of <CODE>N</CODE>. Its type signature - has the form -<PRE> - mkN : Str -> ... -> Str -> P -> ... -> Q -> N -</PRE> - with as many string and parameter arguments as can ever be needed to - construct an <CODE>N</CODE>. -<LI>the most regular cases, with just one string argument: -<PRE> - mkN : Str -> N -</PRE> -<LI>A language-dependent (small) set of functions to handle mild irregularities - and common exceptions. -</UL> - -<P> -For the complement-taking variants, such as <CODE>V2</CODE>, we provide -</P> -<UL> -<LI>a case that takes a <CODE>V</CODE> and all necessary arguments, such - as case and preposition: -<PRE> - mkV2 : V -> Case -> Str -> V2 ; -</PRE> -<LI>a case that takes a <CODE>Str</CODE> and produces a transitive verb with the direct - object case: -<PRE> - mkV2 : Str -> V2 ; -</PRE> -<LI>A language-dependent (small) set of functions to handle common special cases, - such as transitive verbs that are not regular: -<PRE> - mkV2 : V -> V2 ; -</PRE> -</UL> - -<P> -The golden rule for the design of paradigms is that -</P> -<UL> -<LI><I>The user of the library will only need function applications with constants and strings, never any records or tables.</I> -</UL> - -<P> -The discipline of data abstraction moreover requires that the user of the resource -is not given access to parameter constructors, but only to constants that denote -them. This gives the resource grammarian the freedom to change the underlying -data representation if needed. It means that the <CODE>ParadigmsGer</CODE> module has -to define constants for those parameter types and constructors that -the application grammarian may need to use, e.g. -</P> -<PRE> - oper - Case : Type ; - nominative, accusative, genitive, dative : Case ; -</PRE> -<P> -These constants are defined in terms of parameter types and constructors -in <CODE>ResGer</CODE> and <CODE>MorphoGer</CODE>, which modules are not -visible to the application grammarian. -</P> -<A NAME="toc14"></A> -<H3>Lock fields</H3> -<P> -An important difference between <CODE>MorphoGer</CODE> and -<CODE>ParadigmsGer</CODE> is that the former uses "raw" record types -for word classes, whereas the latter used category symbols defined in -<CODE>CatGer</CODE>. When these category symbols are used to denote -record types in a resource modules, such as <CODE>ParadigmsGer</CODE>, -a <B>lock field</B> is added to the record, so that categories -with the same implementation are not confused with each other. -(This is inspired by the <CODE>newtype</CODE> discipline in Haskell.) -For instance, the lincats of adverbs and conjunctions are the same -in <CODE>CommonX</CODE> (and therefore in <CODE>CatGer</CODE>, which inherits it): -</P> -<PRE> - lincat Adv = {s : Str} ; - lincat Conj = {s : Str} ; -</PRE> -<P> -But when these category symbols are used to denote their linearization -types in resource module, these definitions are translated to -</P> -<PRE> - oper Adv : Type = {s : Str ; lock_Adv : {}} ; - oper Conj : Type = {s : Str} ; lock_Conj : {}} ; -</PRE> -<P> -In this way, the user of a resource grammar cannot confuse adverbs with -conjunctions. In other words, the lock fields force the type checker -to function as grammaticality checker. -</P> -<P> -When the resource grammar is <CODE>open</CODE>ed in an application grammar, the -lock fields are never seen (except possibly in type error messages), -and the application grammarian should never write them herself. If she -has to do this, it is a sign that the resource grammar is incomplete, and -the proper way to proceed is to fix the resource grammar. -</P> -<P> -The resource grammarian has to provide the dummy lock field values -in her hidden definitions of constants in <CODE>Paradigms</CODE>. For instance, -</P> -<PRE> - mkAdv : Str -> Adv ; - -- mkAdv s = {s = s ; lock_Adv = <>} ; -</PRE> -<P></P> -<A NAME="toc15"></A> -<H3>Lexicon construction</H3> -<P> -The lexicon belonging to <CODE>LangGer</CODE> consists of two modules: -</P> -<UL> -<LI><CODE>StructuralGer</CODE>, structural words, built by using both - <CODE>ParadigmsGer</CODE> and <CODE>MorphoGer</CODE>. -<LI><CODE>LexiconGer</CODE>, content words, built by using <CODE>ParadigmsGer</CODE> only. -</UL> - -<P> -The reason why <CODE>MorphoGer</CODE> has to be used in <CODE>StructuralGer</CODE> -is that <CODE>ParadigmsGer</CODE> does not contain constructors for closed -word classes such as pronouns and determiners. The reason why we -recommend <CODE>ParadigmsGer</CODE> for building <CODE>LexiconGer</CODE> is that -the coverage of the paradigms gets thereby tested and that the -use of the paradigms in <CODE>LexiconGer</CODE> gives a good set of examples for -those who want to build new lexica. -</P> -<A NAME="toc16"></A> -<H2>Lexicon extension</H2> -<A NAME="toc17"></A> -<H3>The irregularity lexicon</H3> -<P> -It is useful in most languages to provide a separate module of irregular -verbs and other words which are difficult for a lexicographer -to handle. There are usually a limited number of such words - a -few hundred perhaps. Building such a lexicon separately also -makes it less important to cover <I>everything</I> by the -worst-case variants of the paradigms <CODE>mkV</CODE> etc. -</P> -<A NAME="toc18"></A> -<H3>Lexicon extraction from a word list</H3> -<P> -You can often find resources such as lists of -irregular verbs on the internet. For instance, the -Irregular German Verb page -previously found in -<CODE>http://www.iee.et.tu-dresden.de/~wernerr/grammar/verben_dt.html</CODE> -page gives a list of verbs in the -traditional tabular format, which begins as follows: -</P> -<PRE> - backen (du bäckst, er bäckt) backte [buk] gebacken - befehlen (du befiehlst, er befiehlt; befiehl!) befahl (beföhle; befähle) befohlen - beginnen begann (begönne; begänne) begonnen - beißen biß gebissen -</PRE> -<P> -All you have to do is to write a suitable verb paradigm -</P> -<PRE> - irregV : (x1,_,_,_,_,x6 : Str) -> V ; -</PRE> -<P> -and a Perl or Python or Haskell script that transforms -the table to -</P> -<PRE> - backen_V = irregV "backen" "bäckt" "back" "backte" "backte" "gebacken" ; - befehlen_V = irregV "befehlen" "befiehlt" "befiehl" "befahl" "beföhle" "befohlen" ; -</PRE> -<P></P> -<P> -When using ready-made word lists, you should think about -coyright issues. All resource grammar material should -be provided under GNU Lesser General Public License (LGPL). -</P> -<A NAME="toc19"></A> -<H3>Lexicon extraction from raw text data</H3> -<P> -This is a cheap technique to build a lexicon of thousands -of words, if text data is available in digital format. -See the <A HREF="http://www.cs.chalmers.se/~markus/extract/">Extract Homepage</A> -homepage for details. -</P> -<A NAME="toc20"></A> -<H3>Bootstrapping with smart paradigms</H3> -<P> -This is another cheap technique, where you need as input a list of words with -part-of-speech marking. You initialize the lexicon by using the one-argument -<CODE>mkN</CODE> etc paradigms, and add forms to those words that do not come out right. -This procedure is described in the paper -</P> -<P> -A. Ranta. -How predictable is Finnish morphology? An experiment on lexicon construction. -In J. Nivre, M. Dahllöf and B. Megyesi (eds), -<I>Resourceful Language Technology: Festschrift in Honor of Anna Sågvall Hein</I>, -University of Uppsala, -2008. -Available from the <A HREF="http://publications.uu.se/abstract.xsql?dbid=8933">series homepage</A> -</P> -<A NAME="toc21"></A> -<H2>Extending the resource grammar API</H2> -<P> -Sooner or later it will happen that the resource grammar API -does not suffice for all applications. A common reason is -that it does not include idiomatic expressions in a given language. -The solution then is in the first place to build language-specific -extension modules, like <CODE>ExtraGer</CODE>. -</P> -<A NAME="toc22"></A> -<H2>Using parametrized modules</H2> -<A NAME="toc23"></A> -<H3>Writing an instance of parametrized resource grammar implementation</H3> -<P> -Above we have looked at how a resource implementation is built by -the copy and paste method (from English to German), that is, formally -speaking, from scratch. A more elegant solution available for -families of languages such as Romance and Scandinavian is to -use parametrized modules. The advantages are -</P> -<UL> -<LI>theoretical: linguistic generalizations and insights -<LI>practical: maintainability improves with fewer components -</UL> - -<P> -Here is a set of -<A HREF="http://www.cs.chalmers.se/~aarne/geocal2006.pdf">slides</A> -on the topic. -</P> -<A NAME="toc24"></A> -<H3>Parametrizing a resource grammar implementation</H3> -<P> -This is the most demanding form of resource grammar writing. -We do <I>not</I> recommend the method of parametrizing from the -beginning: it is easier to have one language first implemented -in the conventional way and then add another language of the -same family by aprametrization. This means that the copy and -paste method is still used, but at this time the differences -are put into an <CODE>interface</CODE> module. -</P> -<A NAME="toc25"></A> -<H2>Character encoding and transliterations</H2> -<P> -This section is relevant for languages using a non-ASCII character set. -</P> -<A NAME="toc26"></A> -<H2>Coding conventions in GF</H2> -<P> -From version 3.0, GF follows a simple encoding convention: -</P> -<UL> -<LI>GF source files may follow any encoding, such as isolatin-1 or UTF-8; - the default is isolatin-1, and UTF8 must be indicated by the judgement -<PRE> - flags coding = utf8 ; -</PRE> - in each source module. -<LI>for internal processing, all characters are converted to 16-bit unicode, - as the first step of grammar compilation guided by the <CODE>coding</CODE> flag -<LI>as the last step of compilation, all characters are converted to UTF-8 -<LI>thus, GF object files (<CODE>gfo</CODE>) and the Portable Grammar Format (<CODE>pgf</CODE>) - are in UTF-8 -</UL> - -<P> -Most current resource grammars use isolatin-1 in the source, but this does -not affect their use in parallel with grammars written in other encodings. -In fact, a grammar can be put up from modules using different codings. -</P> -<P> -<B>Warning</B>. While string literals may contain any characters, identifiers -must be isolatin-1 letters (or digits, underscores, or dashes). This has to -do with the restrictions of the lexer tool that is used. -</P> -<A NAME="toc27"></A> -<H2>Transliterations</H2> -<P> -While UTF-8 is well supported by most web browsers, its use in terminals and -text editors may cause disappointment. Many grammarians therefore prefer to -use ASCII transliterations. GF 3.0beta2 provides the following built-in -transliterations: -</P> -<UL> -<LI>Arabic -<LI>Devanagari (Hindi) -<LI>Thai -</UL> - -<P> -New transliterations can be defined in the GF source file -<A HREF="../src/GF/Text/Transliterations.hs"><CODE>GF/Text/Transliterations.hs</CODE></A>. -This file also gives instructions on how new ones are added. -</P> - -<!-- html code generated by txt2tags 2.4 (http://txt2tags.sf.net) --> -<!-- cmdline: txt2tags -\-toc Resource-HOWTO.txt --> -</BODY></HTML> |