Operational Semantics for Functional Logic Languages* *This work has been partially supported by CICYT TIC 2001-2705-C03-01, by Acción Integrada Hispano-Alemana HA2001-0059, by Acc. Int. Hispano-Austriaca HU2001-0019, by Acc. Int. Hispano-Italiana HI2000-0161, and by the DFG under grant Ha 2457/1-2.

AbstractIn this work we provide a semantic description of functional logic languages covering notions like laziness, sharing, and non-determinism. Such a semantic description is essential, for instance, to have appropriate language definitions in order to reason about programs and check the correctness of implementations. First, we define a “big-step” semantics in natural style to relate expressions and their evaluated results. Since this semantics is not sufficient to reason about the operational aspects of programs, we also define a “small-step” operational semantics covering the main features of functional logic languages. Finally, we demonstrate the equivalence of the “small-step” semantics and the natural semantics