Exceptional asynchronous session types: session types without tiers

Fowler, S. , Lindley, S., Morris, J. G. and Decova, S. (2019) Exceptional asynchronous session types: session types without tiers. Proceedings of the ACM on Programming Languages, 3(POPL), 28. (doi: 10.1145/3290341)

Abstract

Session types statically guarantee that communication complies with a protocol. However, most accounts of session typing do not account for failure, which means they are of limited use in real applications---especially distributed applications---where failure is pervasive. We present the first formal integration of asynchronous session types with exception handling in a functional programming language. We define a core calculus which satisfies preservation and progress properties, is deadlock free, confluent, and terminating. We provide the first implementation of session types with exception handling for a fully-fledged functional programming language, by extending the Links web programming language; our implementation draws on existing work on effect handlers. We illustrate our approach through a running example of two-factor authentication, and a larger example of a session-based chat application where communication occurs over session-typed channels and disconnections are handled gracefully.

• Item Type: Articles
• Additional Information: This work was supported by EPSRC grants EP/L01503X/1 (EPSRC CDT in Pervasive Parallelism) and EP/K034413/1 (From Data Types to Session TypesÐA Basis for Concurrency and Distribution), and an LFCS internship.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fowler, Dr Simon
• Authors: Fowler, S., Lindley, S., Morris, J. G., and Decova, S.
• College/School: College of Science and Engineering > School of Computing Science
• Journal Name: Proceedings of the ACM on Programming Languages
• Publisher: ACM
• ISSN: 2475-1421
• ISSN (Online): 2475-1421
• Published Online: 02 January 2019
• Copyright Holders: Copyright © 2019 The Authors
• First Published: First published in Proceedings of the ACM on Programming Languages 3(POPL): 28
• Publisher Policy: Reproduced under a Creative Commons License