Experience with Acore: Implementing GHC with Actors

This paper presents a concurrent interpreter for the programming language Guarded Horn Clauses, abbreviated GHC. GHC is a general purpose concurrent logic programming language. It has a clean, simple semantics based upon unification and choice nondeterminism. Unlike typical implementations of GHC in logic programming languages, the interpreter is implemented in the Actor language Acore. The primary motivation for this work was to probe the strengths and weaknesses of Acore as a platform for developing sophisticated programs. We chose to implement a concurrent interpreter for GHC because this large, complex application provided a rich testbed for exploring Actor programming methodology. The interpreter is a pedagogical investigation of the mapping of GHC constructs onto the Actor model. Because we opted for simplicity over efficiency, the interpreter is inefficient in both time and space.