On subtyping, wildcards, and existential types

Authors:
Nicholas Cameron;Sophia Drossopoulou
Affiliations:
Victoria University of Wellington;Imperial College London
Venue:
Proceedings of the 11th International Workshop on Formal Techniques for Java-like Programs
Year:
2009

Citing 12
Cited 6

F-bounded polymorphism for object-oriented programming

FPCA '89 Proceedings of the fourth international conference on Functional programming languages and computer architecture
An interpretation of objects and object types

POPL '96 Proceedings of the 23rd ACM SIGPLAN-SIGACT symposium on Principles of programming languages
Pizza into Java: translating theory into practice

Proceedings of the 24th ACM SIGPLAN-SIGACT symposium on Principles of programming languages
Making the future safe for the past: adding genericity to the Java programming language

Proceedings of the 13th ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications
Comparing object encodings

Information and Computation
Featherweight Java: a minimal core calculus for Java and GJ

ACM Transactions on Programming Languages and Systems (TOPLAS)
Notes on Typed Object-Oriented Programming

TACS '94 Proceedings of the International Conference on Theoretical Aspects of Computer Software
A Statically Safe Alternative to Virtual Types

ECCOP '98 Proceedings of the 12th European Conference on Object-Oriented Programming
A Unifying Type-Theoretic Framework for Objects

STACS '94 Proceedings of the 11th Annual Symposium on Theoretical Aspects of Computer Science
Java(TM) Language Specification, The (3rd Edition) (Java (Addison-Wesley))

Java(TM) Language Specification, The (3rd Edition) (Java (Addison-Wesley))
Variant parametric types: A flexible subtyping scheme for generics

ACM Transactions on Programming Languages and Systems (TOPLAS)
Matching ThisType to subtyping

Proceedings of the 2009 ACM symposium on Applied Computing

Self type constructors

Proceedings of the 24th ACM SIGPLAN conference on Object oriented programming systems languages and applications
Towards a semantic model for Java wildcards

Proceedings of the 12th Workshop on Formal Techniques for Java-Like Programs
Taming wildcards in Java's type system

Proceedings of the 32nd ACM SIGPLAN conference on Programming language design and implementation
Exact type parameterization and ThisType support

TLDI '12 Proceedings of the 8th ACM SIGPLAN workshop on Types in language design and implementation
Constrained kinds

Proceedings of the ACM international conference on Object oriented programming systems languages and applications
Matching MyType to subtyping

Science of Computer Programming

Quantified Score

Hi-index	0.00

Visualization

Abstract

Wildcards are an often confusing part of the Java type system: the behaviour of wildcard types is not fully specified by subtyping, due to wildcard capture, and the rules for type checking are often misunderstood. Their very formulation seems somehow 'different' from the rest of the Java type system, which is based on a simple, nominal hierarchy. We investigate subtyping in models for Java with and without generics and wildcards. We separate subclassing from subtyping, unify subtyping for class and wildcard types using existential types, and show that Java wildcards emerge naturally from the combination of inclusion and parametric polymorphism.