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@@ -47,6 +47,15 @@ Draft %%date(%c)
%--!
=Introduction=
In this Introduction, we will discuss the field of natural language processing
and locate the place of GF in the field. We will continue with a brief history
of GF and its applications, followed by an overview of this book.
This Introduction contains no technical material that is presupposed in
later chapters. Therefore, the practically oriented reader can jump
directly to the Tutorial starting from Chapter 2.
==Natural language application programming==
Making computers understand human language is one of the oldest dreams of
@@ -240,32 +249,123 @@ aspects, our experience is that writing grammars is an excellent introduction
to the problems of linguistics. In this way, theory can be learnt at the
same time as it is motivated by concrete problems.
The book thus starts with a tutorial, which gradually explains all
The book thus starts with a Tutorial (Part I), which gradually explains all
the constructs of the GF programming language. Also the design and style
aspects of grammar engineering are covered, to help the user to scale
up from small to large and possibly collaborative applications.
After the tutorial, the book continues with a "cook book" containing
hints and case studies for advanced users. Moreover, the resource
grammar library is covered in some detail, which will help those
programmers who want to port the library to new languages, but also
motivate linguistically the choices made in the libraries.
A complete reference manual concludes the book, with a quick reference
card as an appendix.
After the Tutorial, the book continues with a manual on building applications
that have embedded grammars as components (Part II). Part III goes through some
examples of more advanced grammar writing, in particular, the internals of the
resource grammar library.
Part IV is a complete reference manual, and the two Appendices
show a grammar of the GF language and a quick reference card of GF.
What is not given much space in the book is theoretical discussions of
GF, especially in comparison to other grammar formalism. Even though important
in the development of GF as a scientifically justified framework, such
discussions are not relevant for programmers who just want to use GF - any more
than, say, a book on Haskell has to include comparisons with Java. In fact,
introducing Haskell by references to Java may make more sense
than comparing GF with DCG or HPSG or LFG: many Haskell learners can
already be expected to know Java, but most GF learners are not expected
to know any grammar formalism, except perhaps BNF.
comparisons with Java in a Haskell introduction would make more sense
than comparisons with DCG or HPSG or LFG in a GF introduction:
many Haskell learners can already be expected to know Java, whereas
most GF learners are not expected
to know any grammar formalisms, except perhaps BNF.
#PARTone
=An overview of the tutorial=
The tutorial gives a hands-on introduction to grammar writing in GF.
We start in Chapter 3
by building a "Hello World" grammar, which covers greetings
in three languages: English (//hello world//),
Finnish (//terve maailma//), and Italian (//ciao mondo//).
This **multilingual grammar** is based on the distinction, central in
GF, between **abstract syntax**
(the logical structure) and **concrete syntax** (the
sequence of words).
From the "Hello World" example, we proceed
in Chapter 4
to a larger grammar for the domain of food.
In this grammar, you can say things like
```
this Italian cheese is delicious
```
in English and Italian. This grammar illustrates how translation is
more than just replacement of words. For instance, the order of
words may have to be changed:
```
Italian cheese ===> formaggio italiano
```
Moreover, words can have different forms, and which forms
they have vary from language to language. For instance,
Italian adjectives usually have four forms where English
has just one:
```
delicious (wine, wines, pizza, pizzas)
vino delizioso, vini deliziosi, pizza deliziosa, pizze deliziose
```
The **morphology** of a language describes the
forms of its words, and the basics of it are explained in Chapter 5.
The complete description of morphology
belongs to resource grammars, whose use is covered in Chapter 6.
However, we will explain all the
programming concepts involved in resource grammars.
In addition to multilinguality, **semantics** is an important aspect of GF
grammars. The concepts needed for "purely linguistic" grammars belong to
the concrete syntax part of GF, whereas semantics is expressed in the abstract
syntax. After the presentation of concrete syntax constructs, we proceed
in Chapter 7 to the enrichment of abstract syntax with **dependent types**,
**variable bindings**, and **semantic definitions**.
Italian is used as the example language of many grammars.
Of course, we will not presuppose that the reader knows any Italian.
We have chosen Italian because it has a rich structure
that illustrates very well the capacities of GF.
Moreover, even those readers who don't know Italian, will find many of
its words familiar. The exercises will encourage the reader to
port the examples to other languages; in fact, many GF
applications work for 5-10 languages.
To learn how to write GF grammars is not the only goal of
this tutorial. We will also explain the most important
commands of the GF system, mostly in passing. With these commands,
simple application programs such as translation and
quiz systems, can be built simply by writing scripts for the
GF system. More complicated applications, such as natural-language
interfaces and dialogue systems, moreover require programming in
some general-purpose language; such applications are covered in Part II.
==Who should read this tutorial==
This tutorial has been written for all programmers
who want to learn to write grammars in GF.
It will go through GF's programming concepts, and does not
presuppose knowledge of any of the main ingredients of GF:
linguistics, functional programming, and type theory.
This knowledge will be introduced as a part of grammar writing
practice.
Thus the tutorial should be accessible to anyone who has some
previous programming experience from any programming language; the basics
of using computers are also presupposed, e.g. the use of
text editors and the management of files.
Those who already know GF well can skip the tutorial part,
or skim thorough it, and go directly to the parts on applications
and advanced grammar writing.
Many of these topics will involve large scale GF programming,
and/or programming in other languages in which GF grammars are embedded.
=Getting started=
In this chapter, we will introduce the GF program and write the first GF grammar,
@@ -274,7 +374,6 @@ how GF can be used for the tasks of translation and multilingual
generation.
==What GF is==
We use the term GF for three different things:
@@ -355,99 +454,6 @@ is given in the libraries.
==Who should read this tutorial==
The tutorial part of this book is mainly for programmers
who want to learn to write application grammars.
It will go through GF's programming concepts, and does not
presuppose knowledge of any of the main ingredients of GF:
linguistics, functional programming, and type theory.
This knowledge will be introduced as a part of grammar writing
practice.
Thus the tutorial should be accessible to anyone who has some
previous programming experience from any programming language; the basics
of using computers are also presupposed, e.g. the use of
text editors and the management of files.
Those who already know GF well can skip the tutorial part,
or skim thorough it, and go directly to the part on advanced applications.
Many of these applications will involve large scale GF programming,
and/or programming in other languages in which GF grammars are embedded.
==The coverage of the tutorial==
The tutorial gives a hands-on introduction to grammar writing.
We start in this chapter
by building a "Hello World" grammar, which covers greetings
in three languages: English (//hello world//),
Finnish (//terve maailma//), and Italian (//ciao mondo//).
This **multilingual grammar** is based on the distinction, central in
GF, between **abstract syntax**
(the logical structure) and **concrete syntax** (the
sequence of words).
From the "Hello World" example, we proceed
in the next chapter
to a larger grammar for the domain of food.
In this grammar, you can say things like
```
this Italian cheese is delicious
```
in English and Italian. This grammar illustrates how translation is
more than just replacement of words. For instance, the order of
words may have to be changed:
```
Italian cheese ===> formaggio italiano
```
Moreover, words can have different forms, and which forms
they have vary from language to language. For instance,
Italian adjectives usually have four forms where English
has just one:
```
delicious (wine, wines, pizza, pizzas)
vino delizioso, vini deliziosi, pizza deliziosa, pizze deliziose
```
The **morphology** of a language describes the
forms of its words, and the basics of it are explained in Chapter 4.
The complete description of morphology
belongs to resource grammars, whose use is covered in Chapter 6.
However, we will explain all the
programming concepts involved in resource grammars, and also
build a miniature resource grammar in order
to give an introduction to linguistically oriented grammar writing (Chapter 5).
Italian is used as the example language of many grammars.
Of course, we will not presuppose that the reader knows any Italian.
We have chosen Italian because it has a rich structure
that illustrates very well the capacities of GF.
Moreover, even those readers who don't know Italian, will find many of
its words familiar. The exercises will encourage the reader to
port the examples to other languages; in fact, many GF
applications work for 5-10 languages.
In addition to multilinguality, **semantics** is an important aspect of GF
grammars. The concepts needed for "purely linguistic" grammars belong to
the concrete syntax part of GF, whereas semantics is expressed in the abstract
syntax. After the presentation of concrete syntax constructs, we proceed
in Chapter 7 to the enrichment of abstract syntax with **dependent types**,
**variable bindings**, and **semantic definitions**.
To learn how to write GF grammars is not the only goal of
this tutorial. We will also explain the most important
commands of the GF system. With these commands,
simple application programs such as translation and
quiz systems, can be built simply by writing scripts for the
GF system.
More complicated applications, such as natural-language
interfaces and dialogue systems, moreover require programming in
some general-purpose language. Part II on advanced applications will
explain how GF grammars are used as components of Haskell and Java programs.
%--!
==Getting the GF program==
@@ -1685,6 +1691,17 @@ The ``.cf`` grammar format.
=Grammars with parameters=
In this Chapter, we will introduce the techniques needed for
describing the inflection of words, as well as the rules by
which propor word forms are selected in syntactic combinations.
These techniques are already needed in a very slight extension
of the Food grammar of the previous Chapter. While explaining
how the linguistic problems are solved for English and Italian,
we also explain all the language constructs GF has for
defining concrete syntax.
==The problem: words have to be inflected==
Suppose we want to say, with the vocabulary included in
@@ -2690,10 +2707,9 @@ now aiming for complete grammatical correctness by the use of parameters.
In this chapter, we will take a look at the GF resource grammar library.
We will use the library to implement a slightly extended ``Food`` grammar
and port it to some new languages.
**Exercise**. Define the mini resource of the previous chapter by
using a functor over the full resource.
and port it to some new languages. Some new concepts of GF's module system
are also introduced, most notably the technique of **parametrized modules**,
which has become an important "design pattern" for multilingual grammars.
==The coverage of the library==
@@ -3310,6 +3326,14 @@ build the terms manually.
=Refining semantics in abstract syntax=
While the concrete syntax constructs of GF have been already
introduced, there is much more that can be done in the abstract
syntax. The techniques of **dependent types** and
**higher order abstract syntax** are introduced in this Chapter,
which thereby concludes the presentation of the GF language.
==GF as a logical framework==
In this section, we will show how
@@ -5033,7 +5057,7 @@ the command
```
% gfdoc
```
provided `gfdoc`` has been installed as a part of one's GF installation.
The `gfdoc`` program is normally installed as a part of GF installation.