teabag a functional logic language debugger：茶的功能逻辑语言调试器.pdf

13th Int. Workshop on Functional and (Constraint) Logic Programming (WFLP04), Aachen, Germany — June 1, 2004. Technical Report, Department of Computer Science of RWTH Aachen, AIB-2004-05, June 2004, pp. 4-18. TeaBag: A Functional Logic Language Debugger Sergio Antoy Stephen Johnson Computer Science Department, Portland State University, P.O. Box 751, Portland, OR 97207, U.S.A. , Abstract. We describe a debugger for functional logic computations. The debugger is an accessory of a virtual machine currently under development. A distinctive feature of this machine is its operational completeness of computations, which places novel demands on a debugger. We give an overview of the debugger’s features, in particular the handling of non- determinism, the ability to control non-deterministic steps, to remove context information, to toggle eager evaluation, and to set breakpoints on both functions and terms. We briefly describe the debugger’s architecture and its interaction with the associated virtual machine. Finally, we describe a short debugging session of a defective program to show in action debugger features and window screenshots. 1 Introduction Functional logic programming joins in a single programming paradigm characterizing features of functional and logic programming. There are a number of languages with this aim, e.g., Curry [23], Escher [26], Le Fun [2], Life [1], Mercury [36], NUE-Prolog [29], Oz [35] and Toy [27], to name a few. These languages support user-defined functions and the subsequent evaluation of expressions involving these functions. Debugging functional computations of this kind is a non-trivial, but well- studied problem [5,14,15,18,31,32,37,38,40,42]. These languages also support the use of logic variables. Debugging programs with the combination of user-defined functions and logic variables is much more challenging for reasons that will be discussed shortly. Indeed, programmi