Declarative Debugging for Encapsulated Search

Declarative debugging has been proposed as a suitable technique for developing debuggers in the context of declarative languages. However, to become really useful debuggers must be able to deal with those parts of the languages that have no clear declarative semantics but are widely used in realistic programs. We explain in this paper how a declarative debugger of wrong answers for the lazy functional-logic language Curry can be extended to debug programs including the encapsulated search, an important feature of this language designed to control non-deterministic computation steps. We show how this can be done without introducing any changes in the compiler.