Analysis-based Refactorings for Haskell

Refactoring is the process of improving the design of existing programs without changing their external behaviour. Refactoring can make a program easier to understand or modify if applied appropriately. Preserving behaviour guarantees that refactoring does not introduce (or remove) any bugs. Refactoring has taken a prominent place in software development and maintenance, but most of the recent success has been in the OO and XP communities. HaRe, the Haskell Refactorer, developed at the University of Kent by Huiqing Li, Claus Reinke and Simon Thompson, is a refactoring tool for Haskell 98. This paper presents a number of new refactorings for HaRe that fall under the category of program-analysis and it also presents some new refactorings that make use of the GHC type-checker; the new architecture for HaRe encompassing the type-checker is also discussed. General Terms Transformation, Refactoring, Program Slicing, Languages, Design