A Logic Programming Language with Lambda - Abstraction , Function Variables , and Simple Uni cationDale

It has been argued elsewhere that a logic programming language with function variables and-abstractions within terms makes a good meta-programming language, especially when an object-language contains notions of bound variables and scope. The Prolog logic programming language and the related Elf and Isabelle systems provide meta-programs with both function variables and-abstractions by containing implementations of higher-order uniication. This paper presents a logic programming language, called L , that also contains both function variables and-abstractions, although certain restrictions are placed on occurrences of function variables. As a result of these restrictions, an implementation of L does not need to implement full higher-order uniication. Instead, an extension to rst-order uniication that respects bound variable names and scopes is all that is required. Such uniication problems are shown to be decidable and to possess most general uniiers when uniiers exist. A uniication algorithm and logic programming interpreter are described and proved correct. Several examples of using L as a meta-programming language are presented.