A Framework for Datatype Transformation

We study one dimension of program evolution, namely the evolution of the datatypes in a program. Both the object programs subject to datatype transformation, and the meta-programs for transformation are functional programs. We cover (semantics-preserving) refactorings, but also structure-extending and -reducing transformations. A corresponding operator suite is designed, a suitable specification approach is worked out, and interactive datatype transformation is enabled. We call the corresponding framework FDT—Framework for Datatype Transformation. We make a number of observations on what specification and interaction techniques are appropriate for datatype transformation, and how it relates to the overall theme of software evolution.