An introduction to the WSL program transformer

The author looks at the reasons for developing program transformation systems and reviews the work in this area. He then presents the argument that program transformation is a valid approach to software maintenance. Next he describes the transformer built into the Maintainer´s Assistant, a tool that aims to help the maintainer recover specifications from code. He shows how it differs from existing systems, in particular, in using a subset of the language it is transforming in order to write the transformations themselves. Finally, he looks at ways of automating the transformation system and other unresolved issues