Reuse by Program Transformation

Certain adaptations, that are usually performed manually by functional programmers are formalized by program transformations in this paper. We focus on adaptations to obtain a more reusable version of a program or a version needed for a special use case. The paper provides a few examples, namely propagation of additional parameters, introduction of monadic style, and symbolic rewriting. The corresponding transformations are specified by inference rules in the style of natural semantics. Preservation properties such as type and semantics preservation are discussed. The overall thesis of this paper is that suitable operator suites for automated adaptations and a corresponding transformational programming style can eventually be combined with other programming styles, such as polymorphic programming, modular programming, or the monadic style, in order to improve reusability of functional programs. ?Partial support received from the Netherlands Organization for Scientific Research (NWO) under the Generation of Program Transformation Systems project