# Grammatical Framework

Version 3.2
December 2010

[ Demos | Download | Libraries | Reference | Tutorial | QuickStart | UserGroup | Book New! ]

[ Wiki | People | Publications | QuickRefCard | LibTutorial | MOLTO | SummerSchool | Android ]

## News

2011-04-15: The GF Book is available.
2011-01-13: Phrasedroid available on the Android Market.
2011-01-04: GF is part of the CLT Toolkit.
2010-12-23: GF 3.2 released! Release notes.
2010-12-22: GF Summer School in Barcelona, 15-26 August 2011.

## 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, but not restricted to programming languages
- a functional language, like Haskell, Lisp, OCaml, Scheme, SML, but specialized to grammar writing
- a natural language processing framework, like LKB, XLE, Regulus, but based on functional programming and type theory
- a categorial grammar formalism, like ACG, CCG, but different and equipped with different tools
- a logical framework, like Agda, Coq, Isabelle, but equipped with concrete syntax in addition to logic

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

- translation systems
- multilingual web gadgets
- natural-language interfaces
- dialogue systems
- natural language resources

## Availability

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

- Linux
- Mac OS X
- Windows
- Android mobile platform (via Java; runtime)
- via compilation to JavaScript, almost any platform that has a web browser (runtime)

## Projects

GF was first created 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, a database query system, a formalization of an alarm system instructions with translations to 5 languages, and an authoring system for medical drug descriptions.

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

- GF-Alfa: natural language interface to formal proofs
- Efficient: authoring tool for business models.
- GF-KeY: authoring and translation of software specifications
- TALK: multilingual and multimodal spoken dialogue systems
- WebALT: multilingual generation of mathematical exercises (commercial project)
- SALDO: Swedish morphological dictionary based on rules developed for GF and Functional Morphology
- MOLTO: multilingual online translation.

Academically, GF has been used in four PhD theses and resulted in around fifty scientific publications (see GF publication list).

## 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, in particular the Android platform
- JavaScript
- 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. Amharic (partial)
2. Arabic (partial)
3. Bulgarian
4. Catalan
5. Danish
6. Dutch
7. English
8. Finnish
9. French
10. German
11. Hindi (fragments)
12. Interlingua
13. Italian
14. Latin (fragments)
15. Nepali
16. Norwegian bokmål
17. Persian
18. Polish
19. Punjabi
20. Romanian
21. Russian
22. Spanish
23. Swedish
24. Thai (fragments)
25. Turkish (fragments)
26. Urdu

Adding a language to the resource library takes 3 to 9 months - contributions are welcome! You can start with the resource grammarian's tutorial.