Jacques: Created page with "Datalog is often used as a programming language nowadays, with complex programs consisting of numerous inter-dependent predicates. But Datalog lacks interactive debugging tech..."

2023-04-27T19:27:39Z

Created page with "Datalog is often used as a programming language nowadays, with complex programs consisting of numerous inter-dependent predicates. But Datalog lacks interactive debugging tech..."

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Datalog is often used as a programming language nowadays, with complex programs consisting of numerous inter-dependent predicates. But Datalog lacks interactive debugging techniques that support the stepwise execution and inspection of the execution state. In this paper, we propose interactive debugging of Datalog programs following a top-down evaluation strategy called recursive query/subquery. While the recursive query/subquery approach is well-known in the literature, we are the first to provide a complete programming-language semantics based on it. Specifically, we develop the first small-step operational semantics for top-down Datalog, where subqueries occur as nested intermediate terms. The small-step semantics forms the basis of step-into interactions in the debugger. Moreover, we show how step-over interactions can be realized efficiently based on a hybrid Datalog semantics that adds a bottom-up database to our top-down operational semantics. We implemented a debugger for core Datalog following these semantics and explain how to adopt it for debugging the frontend languages of Souffle and IncA.

[[File:DatalogDebugging.pdf]]

WG211/M22Erdweg - Revision history

Jacques: Created page with "Datalog is often used as a programming language nowadays, with complex programs consisting of numerous inter-dependent predicates. But Datalog lacks interactive debugging tech..."