API-Driven Generation of Well-Typed Terms

Abstract

In this thesis, a reusable library for defining generators for well-typed expressions in standard Haskell is presented. The expressions are randomly constructed from a set of functions and values specified by a user. Both the types of these functions and the type of the generated expression can be polymorphic and/or higher order, i.e. containing functions with polymorphic types as arguments. The main motivation for this library is for generating test data when testing an Embedded Domain Specific Language (EDSL) where constructing a generator for the language by hand might be both tedious and error-prone. The library was successfully used to define a generator producing terms similar to those computed by such a hand-made generator. The code size and complexity of the final generator was significantly reduced when compared to the hand-made one.