Verifying message-passing programs with dependent behavioural types

Alceste Scalas, Nobuko Yoshida, Elias Benussi

Research output: Chapter in Book/Published conference outputConference publication


Concurrent and distributed programming is notoriously hard. Modern languages and toolkits ease this difficulty by offering message-passing abstractions, such as actors (e.g., Erlang, Akka, Orleans) or processes (e.g., Go): they allow for simpler reasoning w.r.t. shared-memory concurrency, but do not ensure that a program implements a given specification. To address this challenge, it would be desirable to specify and verify the intended behaviour of message-passing applications using types, and ensure that, if a program type-checks and compiles, then it will run and communicate as desired. We develop this idea in theory and practice. We formalise a concurrent functional language λπ, with a new blend of behavioural types (from π-calculus theory), and dependent function types (from the Dotty programming language, a.k.a. the future Scala 3). Our theory yields four main payoffs: (1) it verifies safety and liveness properties of programs via typeś level model checking; (2) unlike previous work, it accurately verifies channel-passing (covering a typical pattern of actor programs) and higher-order interaction (i.e., sending/receiving mobile code); (3) it is directly embedded in Dotty, as a toolkit called Effpi, offering a simplified actor-based API; (4) it enables an efficient runtime system for Effpi, for highly concurrent programs with millions of processes/actors.

Original languageEnglish
Title of host publicationPLDI 2019 - Proceedings of the 40th ACM SIGPLAN Conference on Programming Language Design and Implementation
EditorsKathryn S. McKinley, Kathleen Fisher
Number of pages15
ISBN (Electronic)9781450367127
Publication statusPublished - 8 Jun 2019
Event40th ACM SIGPLAN Conference on Programming Language Design and Implementation, PLDI 2019 - Phoenix, United States
Duration: 22 Jun 201926 Jun 2019


Conference40th ACM SIGPLAN Conference on Programming Language Design and Implementation, PLDI 2019
Country/TerritoryUnited States

Bibliographical note

© ACM, 2019. This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution.


  • Actors
  • Behavioural types
  • Dependent types
  • Dotty
  • Model checking
  • Processes
  • Scala
  • Temporal logic


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