Correctness-by-Construction Meets Refinement Types

Type systems provide specifications and enable reasoning about the programs. Among other benefits, type systems provide guarantees of the absence of certain (ill-typed) program behaviors. Refinement types further enrich the expressiveness of type systems by allowing a predicate alongside the type. The crucial divide by zero and null pointer errors are safely eliminated with refinement types. Interestingly, Correctness-by-Construction (CbC) also provides a way to set specifications for the programs. The specifications are provided for the smaller modules. Larger programs are built by composing the functionally correct smaller modules. Therefore, CbC naturally results in verified and correct programs following the program specifications. In this short paper, we highlight that CbC meets refinement types in a sense that both approaches provide specifications for program correctness and larger programs are built by composing the functionally correct smaller modules.