Gradual session types. (2019)

• Record Type: Journal Article
• Authors: IGARASHI, ATSUSHI; THIEMANN, PETER; TSUDA, YUYA; VASCONCELOS, VASCO T.; WADLER, PHILIP
• Is Part Of: Journal of functional programming. Volume 29(2019)
• Publication Date: 2019
• Subjects: Functional programming (Computer science) -- Periodicals
• DOI: 10.1017/S0956796819000169
• Languages: English
• ISSNs: 0956-7968

Abstract

Abstract: Session types are a rich type discipline, based on linear types, that lifts the sort of safety claims that come with type systems to communications. However, web-based applications and microservices are often written in a mix of languages, with type disciplines in a spectrum between static and dynamic typing. Gradual session types address this mixed setting by providing a framework which grants seamless transition between statically typed handling of sessions and any required degree of dynamic typing. We propose Gradual GV as a gradually typed extension of the functional session type system GV. Following a standard framework of gradual typing, Gradual GV consists of an external language, which relaxes the type system of GV using dynamic types; an internal language with casts, for which operational semantics is given; and a cast-insertion translation from the former to the latter. We demonstrate type and communication safety as well as blame safety, thus extending previous results to functional languages with session-based communication. The interplay of linearity and dynamic types requires a novel approach to specifying the dynamics of the language.