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.
Description
This work is licensed under a Creative Commons Attribution 4.0 International License.
Citation
Simon Fowler, Sam Lindley, J. Garrett Morris, and Sára Decova. 2019. Exceptional asynchronous session types: session types without tiers. Proc. ACM Program. Lang. 3, POPL, Article 28 (January 2019), 29 pages. DOI:https://doi.org/10.1145/3290341