Software measurement for functional programming

This thesis presents an investigation into the usefulness of software measurement techniques, also known as software metrics, for software written in functional programming languages such as Haskell. Statistical analysis is performed on a selection of metrics for Haskell programs, some taken from the world of imperative languages. An attempt is made to assess the utility of various metrics in predicting likely places that bugs may occur in practice by correlating bug fixes with metric values within the change histories of a number of case study programs. This work also examines mechanisms for visualising the results of the metrics and shows some proof of concept implementations for Haskell programs, and notes the usefulness of such tools in other software engineering processes such as refactoring. This research makes the following contributions to the field of software engineering for functional programs. • A collection of metrics for use with functional programs has been identified from the existing metrics used with other paradigms. • The relationship between the metrics and the change history of a small collection of programs has been explored. • The relationships between the individual metrics on a large collection of programs has been explored. • Visualisation tools have been developed for further exploring the metric values in conjunction with program source code. xxii Acknowledgements I would like to express my thanks to the Engineering and Physical Sciences Research Council for funding this work and to Microsoft Research for the time I spent at their Cambridge research lab in November 2000. I would also like to extend my thanks to my supervisor, Professor Simon Thompson, for guiding me through this work and for the countless hours of proof reading. My personal thanks must go to my mother, father and sister for their support throughout my university life. I could not have wished for better parents or a more supportive family and could not have completed this work without them. And finally, to Kristina for pushing me to finish the corrections. Thank you.