arXiv subjects

Alen Arslanagić

Publications and source records attributed to Alen Arslanagić.

3 recordsLinked to original sources

arXiv2025

A Minimal Formulation of Session Types: The Sessions of Trios in Concert

Session types are a type-based approach to the verification of message-passing programs. They specify communication structures essential to enforcing program correctness; by relying on sequencing constructs, a session type can precisely describe the intended order of communication actions through a channel. In this paper we study a fragment of session types that makes a very limited use of sequencing; we call it minimal session types. In the context of a core process calculus with sessions and higher-order concurrency, we establish two technical results. First, we prove that every process P typable with standard session types can be compiled down into a process D(P) typable with minimal session types. Second, we prove that P and D(P) are behaviorally equivalent. These results show that having sequencing in both processes and session types is convenient, but that only sequencing in processes is truly indispensable, as it can correctly codify sequencing in types. Our developments draw inspiration from work by Parrow on behavior-preserving decompositions of untyped processes using trios, i.e., processes with exactly three nested prefixes. By casting Parrow's approach in the realm of typed processes, our developments reveal a conceptually simple formulation of session types, supported by static and dynamic correctness results.

cs.PL↗

arXiv2022

Scalable Typestate Analysis for Low-Latency Environments

Static analyses based on typestates are important in certifying correctness of code contracts. Such analyses rely on Deterministic Finite Automata (DFAs) to specify properties of an object. We target the analysis of contracts in low-latency environments, where many useful contracts are impractical to codify as DFAs and/or the size of their associated DFAs leads to sub-par performance. To address this bottleneck, we present a lightweight typestate analyzer, based on an expressive specification language that can succinctly specify code contracts. By implementing it in the static analyzer Infer, we demonstrate considerable performance and usability benefits when compared to existing techniques. A central insight is to rely on a sub-class of DFAs with efficient bit-vector operations.

cs.PL↗

arXiv2019

Minimal Session Types (Extended Version)

Session types are a type-based approach to the verification of message-passing programs. They have been much studied as type systems for the pi-calculus and for languages such as Java. A session type specifies what and when should be exchanged through a channel. Central to session-typed languages are constructs in types and processes that specify sequencing in protocols. Here we study minimal session types, session types without sequencing. This is arguably the simplest form of session types. By relying on a core process calculus with sessions and higher-order concurrency (abstraction passing), we prove that every process typable with usual (non minimal) session types can be compiled down into a process typed with minimal session types. This means that having sequencing constructs in both processes and session types is redundant; only sequentiality in processes is indispensable, as it can precisely codify sequentiality in types. Our developments draw inspiration from work by Parrow on behavior-preserving decompositions of untyped processes. By casting Parrow's results in the realm of typed processes, our results reveal a conceptually simple formulation of session types and a principled avenue to the integration of session types into languages without sequencing in types.

cs.LO↗