Actris: Session-type based reasoning in separation logic

Jonas Kastberg Hinrichsen, Jesper Bengtson, Robbert Krebbers

Research output: Contribution to journalArticleScientificpeer-review

19 Citations (Scopus)
51 Downloads (Pure)


Message passing is a useful abstraction to implement concurrent programs. For real-world systems, however, it is often combined with other programming and concurrency paradigms, such as higher-order functions, mutable state, shared-memory concurrency, and locks. We present Actris: a logic for proving functional correctness of programs that use a combination of the aforementioned features. Actris combines the power of modern concurrent separation logics with a first-class protocol mechanism - based on session types - for reasoning about message passing in the presence of other concurrency paradigms. We show that Actris provides a suitable level of abstraction by proving functional correctness of a variety of examples, including a distributed merge sort, a distributed load-balancing mapper, and a variant of the map-reduce model, using relatively simple specifications. Soundness of Actris is proved using a model of its protocol mechanism in the Iris framework. We mechanised the theory of Actris, together with tactics for symbolic execution of programs, as well as all examples in the paper, in the Coq proof assistant.

Original languageEnglish
Article number6
Pages (from-to)1-30
JournalProceedings of the ACM on Programming Languages
Issue numberPOPL
Publication statusPublished - 2020


  • Actor model
  • Concurrency
  • Iris
  • Message passing
  • Session types


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