Designing, developing and maintaining concurrent applications is an error-prone and time-consuming task; most difficulties arise because compilers are usually unable to check whether the inputs/outputs performed by a program at runtime will adhere to a given protocol specification. To address this problem, we propose lightweight session programming in Scala: we leverage the native features of the Scala type system and standard library, to introduce (1) a representation of session types as Scala types, and (2) a library, called lchannels, with a convenient API for session-based programming, supporting local and distributed communication. We generalise the idea of Continuation-Passing Style Protocols (CPSPs), studying their formal relationship with session types. We illustrate how session programming can be carried over in Scala: how to formalise a communication protocol, and represent it using Scala classes and lchannels, letting the compiler help spotting protocol violations. We attest the practicality of our approach with a complex use case, and evaluate the performance of lchannels with a series of benchmarks.
@InProceedings{scalas_et_al:LIPIcs.ECOOP.2016.21, author = {Scalas, Alceste and Yoshida, Nobuko}, title = {{Lightweight Session Programming in Scala}}, booktitle = {30th European Conference on Object-Oriented Programming (ECOOP 2016)}, pages = {21:1--21:28}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-014-9}, ISSN = {1868-8969}, year = {2016}, volume = {56}, editor = {Krishnamurthi, Shriram and Lerner, Benjamin S.}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECOOP.2016.21}, URN = {urn:nbn:de:0030-drops-61156}, doi = {10.4230/LIPIcs.ECOOP.2016.21}, annote = {Keywords: session types, Scala, concurrency} }
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