Year: 2022
Type: article
Abstract: Session types statically describe communication protocols between concurrent message-passing processes. Unfortunately, parametric polymorphism even in its restricted prenex form is not fully understood in the context of session types. In this article, we present the metatheory of session types extended with prenex polymorphism and, as a result, nested recursive datatypes. Remarkably, we prove that type equality is decidable by exhibiting a reduction to trace equivalence of deterministic first-order grammars. Recognizing the high theoretical complexity of the latter, we also propose a novel type equality algorithm and prove its soundness. We observe that the algorithm is surprisingly efficient and, despite its incompleteness, sufficient for all our examples. We have implemented our ideas by extending the Rast programming language with nested session types. We conclude with several examples illustrating the expressivity of our enhanced type system.
DOI: 10.1145/3539656
Institutions: Carnegie Mellon University, University of Lisbon
Language: English
Subfield: Artificial Intelligence
Field: Computer Science
Domain: Physical Sciences
Open Access status: hybrid
Awards: LASIGE - Extreme Computing, LASIGE - Extreme Computing, Programação Concorrente Segura com Tipos de Sessão, G5240966281, G6671297155, CAREER: Marlin: A Unified Framework for Automatic and Interactive Quantitative Program Analysis, SaTC: CORE: Medium: Collaborative: Automated Support for Writing High-Assurance Smart Contracts
OpenAlex ID: W4285489720