# Grammatical Framework

Version 3.0

June 2008

`|` Demos `|` Download `|` Development `|` Events `|` Libraries `|` People `|` Projects `|` Publications `|` Reference `|` Tutorial `|`

## News

27 June 2008: release of GF 3.0 and a new web page; the old web page is here.

## What is GF

GF, Grammatical Framework, is a programming language for multilingual grammar applications. It is

- a special-purpose language for grammars, like YACC, Bison, Happy, BNFC
- a functional language, like Haskell, Lisp, OCaml, Scheme, SML
- a natural language processing framework, like LKB, XLE, Regulus
- a categorial grammar formalism, like ACG, CCG
- a logical framework, like Agda, Coq, Isabelle

Don't worry if you don't know most of the references above - but if you do know at least one, it may help you to get a first idea of what GF is.

## Applications

GF can be used for building

- [text translators ]
- [speech translators ]
- [natural-language interfaces ]
- [multilingual web pages ]
- [multilingual authoring systems ]
- [dialogue systems ]
- [language training systems ]
- [natural language resources ]

## Availability

GF is open-source, licensed under [GPL ] (the program) and [LGPL ] (the libraries). It is available for

- [Linux ]
- [Mac OS X ]
- [Windows ]
- via compilation to [JavaScript ], almost any platform that has a web browser

## Projects

GF was born in 1998 at Xerox Research Centre Europe, Grenoble in the project Multilingual Document Authoring. At Xerox, it was used for prototypes including a restaurant phrase book in 6 languages, a database query system in 7 languages, a formalization of an alarm system instructions with translations to 5 languages, and an authoring system for medical drug descriptions in 2 languages.

Later projects using GF and involving third parties include, in chronological order,

- GF-Alfa: natural language interface to formal proofs
- GF-KeY: authoring and translation of software specifications
- TALK: multilingual and multimodal spoken dialogue systems
- WebALT: multilingual generation of mathematical exercises (commercial project)
- MultiWiki: multilingual Wiki for restaurant reviews
- SALDO: Swedish morphological dictionary based on tools developed for GF

Academically, GF has been used in four [PhD theses ], and resulted in around fifty [scientific publications ].

## Programming in GF

GF is easy to learn by following the tutorial. You can write your first translator in 15 minutes.

GF has an interactive command interpreter, as well as a batch compiler. Grammars can be compiled to parser and translator code in many different formats. These components can then be embedded in applications written in other programming languages. The formats currently supported are:

- Haskell
- Java
- JavaScript
- Prolog
- Speech recognition: HTK/ATK, Nuance, JSGF

The GF programming language is high-level and advanced, featuring

- static type checking
- higher-order functions
- dependent types
- pattern matching with data constructors and regular expressions
- module system with multiple inheritance and parametrized modules

## Libraries

Libraries are at the heart of modern software engineering. In natural language applications, libraries are a way to cope with thousands of details involved in syntax, lexicon, and inflection. The GF resource grammar library has support for an increasing number of languages, currently including

1. Arabic (partial)
2. Bulgarian
3. Catalan (partial)
4. Danish
5. English
6. Finnish
7. French
8. German
9. Hindi/Urdu (fragments)
10. Interlingua
11. Italian
12. Norwegian bokmål
13. Russian
14. Spanish
15. Swedish
16. Thai (fragments)

Adding a language to the resource library takes 3 to 9 months - contributions are welcome!