Grammatical framework
Grammatical Framework (GF) is a programming language for writing grammars of natural languages. GF is capable of parsing and generating texts in several languages simultaneously while working from a language-independent representation of meaning. Grammars written in GF can be compiled into different formats including JavaScript and Java and can be reused as software components. A companion to GF is the GF Resource Grammar Library, a reusable library for dealing with the morphology and syntax of a growing number of natural languages.
Both GF itself and the GF Resource Grammar Library are open-source. Typologically, GF is a functional programming language. Mathematically, it is a type-theoretic formal system (a logical framework to be precise) based on Martin-Löf's intuitionistic type theory, with additional judgments tailored specifically to the domain of linguistics.
This example is taken from the LREC 2010 tutorial
Goal: write a multilingual grammar for expressing statements about John and Mary loving each other.
In GF, grammars are divided to two module types:
Consider the following:
Abstract syntax
Concrete syntax: English
Notice: Str (token list or "string") as the only linearization type.
A single abstract syntax may be applied to many concrete syntaxes, in our case one for each new natural language we wish to add. The same system of trees can be given:
Concrete syntax: French
We can now use our grammar to translate phrases between French and English. The following commands can be executed in the GF interactive shell.
Import many grammars with the same abstract syntax
Translation: pipe linearization to parsing
Multilingual generation: linearize into all languages
Latin has cases: nominative for subject, accusative for object.
We use a parameter type for case (just 2 of Latin's 6 cases). The linearization type of NP is a table type: from Case to Str. The linearization of John is an inflection table. When using an NP, we select (!) the appropriate case from the table.
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