Synthesis of Bidirectional Programs from Examples with Functional Dependencies

Abstract

Although many advanced synthesizers can generate unidirectional programs on relations (tables of relational database systems) from user-provided examples, the difficulty of synthesizing bidirectional programs - each being a well-behaved pair comprising a forward program and a backward program - from examples involving tables that have internal functional dependencies, still remains an unsolved issue. In this paper, we propose an approach that leverages the cutting-edge template-based synthesizer, P_ROS_YNTH, to achieve the synthesis of bidirectional programs from examples with functional dependencies. We forward propagate functional dependencies from the source through intermediate relations to the view via a set of atomic forward programs, which together compose a complete forward program. Then, we illustrate how to formulate Datalog templates that encapsulate well-behaved view update strategies with minimal effects, along with additional templates that capture the constraints and effects introduced by the specified functional dependencies. Utilizing these templates, P_ROS_YNTH could be employed to synthesize atomic backward programs that can subsequently be combined to form a complete backward program. We have implemented our proposed approach in a prototype named S_YNTHBP and evaluated it on 38 practical benchmarks. Our evaluation shows that S_YNTHBP is able to automate 37 of these benchmarks effectively.