Machine-Checked Semantic Session Typing

Jonas Kastberg Hinrichsen, Daniël Louwrink, Robbert Krebbers, Jesper Bengtson

Research output: Conference Article in Proceeding or Book/Report chapterArticle in proceedingsResearchpeer-review


Session types—a family of type systems for message-passing concurrency—have been subject to many extensions, where each extension comes with a separate proof of type safety. These extensions cannot be readily combined, and their proofs of type safety are generally not machine checked, making their correctness less trustworthy. We overcome these shortcomings with a semantic approach to binary asynchronous affine session types, by developing a logical relations model in Coq using the Iris program logic. We demonstrate the power of our approach by combining various forms of polymorphism and recursion, asynchronous subtyping, references, and locks/mutexes. As an additional benefit of the semantic approach, we demonstrate how to manually prove typing judgements of racy, but safe, programs that cannot be type checked using only the rules of the type system.
Original languageEnglish
Title of host publicationCPP 2021: Proceedings of the 10th ACM SIGPLAN International Conference on Certified Programs and Proofs
PublisherAssociation for Computing Machinery
Publication date2021
Publication statusPublished - 2021


  • Message passing
  • Session types
  • Separation logic
  • Semantic typing
  • Iris
  • Coq


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