What is GF?

GF is a framework for defining multilingual grammars, each based on a common abstract syntax. The abstract syntax is defined by using type theory, in the same way as in logical frameworks. The natural language generation part is called concrete syntax, which is a feature-based grammar formalism equivalent to PMCFG (Parallel Multiple Context-Free Grammars) and has polynomial parsing behaviour. GF uses PMCFG as its "machine language", which is compiled from high-level grammar code that features a rich type system and a module system inherited from functional programming languages.