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The Design and Formalization of Mezzo, a Permission-Based Programming Language

The programming language Mezzo is equipped with a rich type system that controls aliasing and access to mutable memory. We give a comprehensive tutorial overview of the language. Then we present a modular formalization of Mezzo’s core type system, in the form of a concurrent λ-calculus, which we successively extend with references, locks, and adoption and abandon, a novel mechanism that marries Mezzo’s static ownership discipline with dynamic ownership tests. We prove that well-typed programs do not go wrong and are data-race free. Our definitions and proofs are machine checked.