A Model for Java with Wildcards

Cameron, Nicholas; Drossopoulou, Sophia; Ernst, Erik

doi:10.1007/978-3-540-70592-5_2

Cited by 50 publications

(60 citation statements)

References 17 publications

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“…Lemma 6 is probably the main one, which relates subtyping and wildcard capture, and is similar to lemma 36 from [4]. It states that the method receiver's ability to perform wildcard capture is preserved in subtypes with respect to the method receiver.…”

Section: Type Soundnessmentioning

confidence: 79%

“…An alternative approach to variance is use-site variance [11,18,4]. Instead of declaring the variance of X at its definition site, generics are assumed to be invariant in their type parameters.…”

Section: Use-site Variancementioning

confidence: 99%

“…Our formalism has to model wildcard capture and its interaction with definition-site variance. This handling comprises some of the more significant changes of our formalism relative to TameFJ [4].…”

Section: Realistic Complicationsmentioning

confidence: 99%

“…The definition of sift required updating because of interaction with variant types. First, we give a brief overview of expression typing; see [4] for more thorough coverage.…”

Section: Typing and Wildcard Capturementioning

confidence: 99%

“…The same flexibility also proved challenging to both researchers and practitioners. The soundness of wildcards in Java has only recently been proven [4], and the implementation of wildcards has been mired in issues [5,15,16].…”

Section: Related Workmentioning

confidence: 99%

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Java Wildcards Meet Definition-Site Variance

Altidor

Reichenbach

Smaragdakis

2012

ECOOP 2012 – Object-Oriented Programming

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Abstract. Variance is concerned with the interplay of parametric polymorphism (i.e., templates, generics) and subtyping. The study of variance gives answers to the question of when an instantiation of a generic class can be a subtype of another. In this work, we combine the mechanisms of use-site variance (as in Java) and definition-site variance (as in Scala and C#) in a single type system, based on Java. This allows maximum flexibility in both the specification and use of generic types, thus increasing the reusability of code. Our VarJ calculus achieves a safe synergy of def-site and use-site variance, while supporting the full complexities of the Java realization of variance, including F-bounded polymorphism and wildcard capture. We show that the interaction of these features with definition-site variance is non-trivial and offer a full proof of soundness-the first in the literature for an approach combining variance mechanisms.

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Section: Type Soundnessmentioning

confidence: 79%

Section: Use-site Variancementioning

confidence: 99%

Section: Realistic Complicationsmentioning

confidence: 99%

“…The definition of sift required updating because of interaction with variant types. First, we give a brief overview of expression typing; see [4] for more thorough coverage.…”

Section: Typing and Wildcard Capturementioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

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Java Wildcards Meet Definition-Site Variance

Altidor

Reichenbach

Smaragdakis

2012

ECOOP 2012 – Object-Oriented Programming

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Existential Quantification for Variant Ownership

Cameron

Drossopoulou

2009

Programming Languages and Systems

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Abstract. Ownership types characterize the topology of objects in the heap, through a characterization of the context to which an object belongs. They have been used to support reasoning, memory management, concurrency, etc. Subtyping is traditionally invariant w.r.t. contexts, which has often proven inflexible in some situations. Recent work has introduced restricted forms of subtype variance and unknown context, but in a rather ad-hoc and restricted way.We develop Jo∃, a calculus which supports parameterisation of types, as well as contexts, and allows variant subtyping of contexts based on existential quantification. Jo∃ is more expressive, general, and uniform than previous works which add variance to ownership languages. Our explicit use of existential types makes the connection to type-theoretic foundations from existential types more transparent. We prove type soundness for Jo∃ and extend it to Jo∃ deep which enforces the owners-as-dominators property.

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On the Decidability of Subtyping with Bounded Existential Types

Wehr

Thiemann

2009

Programming Languages and Systems

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A Model for Java with Wildcards

Cited by 50 publications

References 17 publications

Java Wildcards Meet Definition-Site Variance

Java Wildcards Meet Definition-Site Variance

Existential Quantification for Variant Ownership

On the Decidability of Subtyping with Bounded Existential Types

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