Semantic Subtyping for Objects and Classes

Dardha, Ornela; Gorla, Daniele; Varacca, Daniele

doi:10.1007/978-3-642-38592-6_6

Cited by 5 publications

(13 citation statements)

References 25 publications

(22 reference statements)

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“…The soundness direction is mostly straightforward, as most SR rules have an immediate SD counterpart (or require one extra application of transitivity). In the case of SR NF, the induction hypothesis of the proof, NF(τ 1 ) ≤ τ 2 , and the fact that τ 1 ≤ NF(τ 1 ) according to (10), allow to conclude…”

Section: Reductive Subtypingmentioning

confidence: 96%

“…Frisch et al [11] presented decidable semantic subtyping for a language with functions, products, and boolean combinators (union, intersection, negation); the decision procedure for τ 1 <: τ 2 is based on checking the emptiness of τ 1 \τ 2 . Dardha et al [10] adopted semantic subtyping to objects with structural types, and Ancona and Corradi [2] proposed decidable semantic subtyping for mutable records. Unlike these works, we are interested in applying semantic reasoning to a dynamic language with nominal types.…”

Section: Related Workmentioning

confidence: 99%

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Decidable tag-based semantic subtyping for nominal types, tuples, and unions

Belyakova

2019

Proceedings of the 21st Workshop on Formal Techniques for Java-Like Programs

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Semantic subtyping enables simple, set-theoretical reasoning about types by interpreting a type as the set of its values. Previously, semantic subtyping has been studied primarily in the context of statically typed languages with structural typing. In this paper, we explore the applicability of semantic subtyping in the context of a dynamic language with nominal types. Instead of static type checking, dynamic languages rely on run-time checking of type tags associated with values, so we propose using the tags for semantic subtyping. We base our work on a fragment of the Julia language and present tag-based semantic subtyping for nominal types, tuples, and unions, where types are interpreted set-theoretically as sets of type tags. The proposed subtyping relation is shown to be decidable, and a corresponding analytic definition is provided. The implications of using semantic subtyping for multiple dispatch are also discussed.CCS Concepts • Software and its engineering → Formal language definitions;

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Section: Reductive Subtypingmentioning

confidence: 96%

Section: Related Workmentioning

confidence: 99%

Decidable tag-based semantic subtyping for nominal types, tuples, and unions

Belyakova

2019

Proceedings of the 21st Workshop on Formal Techniques for Java-Like Programs

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“…In semantic subtyping one constructs a set-theoretic model and an interpretation of types as sets in that model; two types are then considered to be subtypes whenever their corresponding sets in the model are subsets. The challenge, then, is to show that this subtype relation derived from the model is decidable for the type system at hand, and there has been impressive work achieving this for various type systems [Ancona and Corradi 2016;Castagna and Xu 2011;Dardha et al 2013;Frisch et al 2002Frisch et al , 2008Hosoya and Pierce 2003]. In particular, the work on semantic subtyping provides powerful reasoning for union and intersection types due to their obvious correspondence to unions and intersections of sets, and is able to recognize subtypings such as the above example regarding Julia's union and covariant tuple types.…”

Section: Semantic Subtypingmentioning

confidence: 99%

Empowering union and intersection types with integrated subtyping

Muehlboeck

Tate

2018

Proc. ACM Program. Lang.

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Union and intersection types are both simple and powerful but have seen limited adoption. The problem is that, so far, subtyping algorithms for type systems extended with union and intersections have typically been either unreliable or insufficiently expressive. We present a simple and composable framework for empowering union and intersection types so that they interact with the rest of the type system in an intuitive and yet still decidable manner. We demonstrate the utility of this framework by illustrating the impact it has made throughout the design of the Ceylon programming language developed by Red Hat.

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“…In the latter, subtyping relation is established only by analysing the structure of a class, i.e., its fields and methods: class (or interface) A is a subtype of class (or interface) B if and only if the fields and methods of A are a superset of the fields and methods of B, and their types in A are subtypes of their types in B. On the other hand, in [32] the authors integrate both the nominal and the structural subtyping in Featherweight Java-like calculus.…”

Section: Subtyping Relationmentioning

confidence: 99%

Type Systems for Distributed Programs: Components and Sessions

Dardha

2016

Atlantis Studies in Computing

Self Cite

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Modern software systems, in particular distributed ones, are everywhere around us and are at the basis of our everyday activities. Hence, guaranteeing their correctness, consistency and safety is of paramount importance. Their complexity makes the verification of such properties a very challenging task. It is natural to expect that these systems are reliable and above all usable.i) In order to be reliable, compositional models of software systems need to account for consistent dynamic reconfiguration, i.e., changing at runtime the communication patterns of a program.ii) In order to be useful, compositional models of software systems need to account for interaction, which can be seen as communication patterns among components which collaborate together to achieve a common task.The aim of the Ph.D. was to develop powerful techniques based on formal methods for the verification of correctness, consistency and safety properties related to dynamic reconfiguration and communication in complex distributed systems. In particular, static analysis techniques based on types and type systems appeared to be an adequate methodology, considering their success in guaranteeing not only basic safety properties, but also more sophisticated ones like, deadlock or livelock freedom in a concurrent setting.The main contributions of this dissertation are twofold. i) On the components side: we design types and a type system for a concurrent object-oriented calculus to statically ensure consistency of dynamic reconfigurations related to modifications of communication patterns in a program during execution time.3 ii) On the communication side: we study advanced safety properties related to communication in complex distributed systems like deadlock-freedom, livelockfreedom and progress.Most importantly, we exploit an encoding of types and terms of a typical distributed language, session π-calculus, into the standard typed π-calculus, in order to understand the expressive power of concurrent calculi with structured communication primitives and how they stand with respect to the standard typed concurrent calculi, namely (variants) of typed π-calculus. Then, we show how to derive in the session π-calculus basic properties, like type safety or complex ones, like progress, by encoding.

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Semantic Subtyping for Objects and Classes

Cited by 5 publications

References 25 publications

Decidable tag-based semantic subtyping for nominal types, tuples, and unions

Decidable tag-based semantic subtyping for nominal types, tuples, and unions

Empowering union and intersection types with integrated subtyping

Type Systems for Distributed Programs: Components and Sessions

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