Transformation and Debugging of Functional Logic Programs

The Italian contribution to functional-logic programming has been significant and influential in a number of areas of semantics, and semantics-based program manipulation techniques. We survey selected topics, with a particular regard to debugging and transformation techniques. These results as usual depend on the narrowing strategy which is adopted and on the properties satisfied by the considered programs. In this paper, we restrict ourselves to first-order functional-logic languages without non-deterministic functions. We start by describing some basic classical transformation techniques, namely folding and unfolding. Then, we recall the narrowing-driven partial evaluation, which is the first generic algorithm for the specialization of functional logic programs. Regarding debugging, we describe a goal-independent approach to automatic diagnosis and correction which applies the immediate consequence operator modeling computed answers to the diagnosis of bugs in functional logic programs. A companion bug-correction program synthesis methodology is described that attempts to correct the erroneous components of the wrong code