Tool Demonstration: Functional Morphology

We will present Functional Morphology [5], abbreviated FM, which is a tool that implements a methodology for constructing natural language morphologies in the functional language Haskell [8]. FM has its own runtime system that supports morphological analysis and synthesis. Moreover, a morphology implemented in FM can be compiled to many other source formats. FM adopts a word-and-paradigm view of morphology: it represents a morphology as a set of inflection tables, paradigms, and the lexicon as a set of dictionary words each tagged with a pointer to an inflection table. The basic idea behind FM is simple, instead of working with untyped regular expressions, which is the state of the art of morphology in computational linguistics, we use finite functions over hereditarily finite algebraic data types. These data types and functions constitute the language-dependent part of the morphology. The language-independent part consists of an untyped dictionary format which is used for synthesis of word forms, translations to other formats, and a decorated trie, which is used for analysis. Functional Morphology builds on ideas introduced by Huet [6] in his computational linguistics toolkit Zen, which he has used to implement the morphology of Sanskrit. In particular, Huet’s ideas about sandhi in Sanskrit have been adopted to a language independent description of compound analysis in FM. The goal of FM has been to make it easy for linguists, who are not trained as functional programmers, to implement the morphology of a new language. In addition to the ease of programming, FM attempts to exploit the high level of abstraction provided by functional programming to make it possible to capture linguistic generalizations. A morphology written in FM has a type system, which defines the inflectional and inherent parameters of the language described. By using algebraic data types, the type system can guarantee that no spurious parameter combinations appear in the morphology description, at the same time as all meaningful combinations are defined. The use of the functional language Haskell provides, besides typing, many other language features that simplify the development of a morphology: higherorder functions, functions as first class objects, give the possibility of defining