A Type Based Debugging Tool for Untyped Logic Languages

This paper presents a method for debugging type errors in untyped logic programs by generating type information based on abstract interpretation with OLDT resolution. The notion \type" is extended to enable the phenomena in logic programs to be described more precisely. The classes Single Types and Collected Types are introduced. An extended OLDT resolution performs combination of derived single types to collected types. Application of the diierent types for debugging unmodular and modular logic programs is discussed, and an extension of the module interface format proposed.