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Author Ancona, Davide ♦ Corradi, Andrea
Source ACM Digital Library
Content type Text
Publisher Association for Computing Machinery (ACM)
File Format PDF
Language English
Subject Domain (in DDC) Computer science, information & general works ♦ Computer programming, programs & data
Subject Keyword Read/write field annotations ♦ Semantic subtyp- ing ♦ Structural types for objects
Abstract Semantic subtyping is an approach for defining sound and complete procedures to decide subtyping for expressive types, including union and intersection types; although it has been exploited especially in functional languages for XML based programming, recently it has been partially investigated in the context of object-oriented languages, and a sound and complete subtyping algorithm has been proposed for record types, but restricted to immutable fields, with union and recursive types interpreted coinductively to support cyclic objects. In this work we address the problem of studying semantic subtyping for imperative object-oriented languages, where fields can be mutable; in particular, we add read/write field annotations to record types, and, besides union, we consider intersection types as well, while maintaining coinductive interpretation of recursive types. In this way, we get a richer notion of type with a flexible subtyping relation, able to express a variety of type invariants useful for enforcing static guarantees for mutable objects. The addition of these features radically changes the defi- nition of subtyping, and, hence, the corresponding decision procedure, and surprisingly invalidates some subtyping laws that hold in the functional setting. We propose an intuitive model where mutable record val- ues contain type information to specify the values that can be correctly stored in fields. Such a model, and the correspond- ing subtyping rules, require particular care to avoid circularity between coinductive judgments and their negations which, by duality, have to be interpreted inductively. A sound and complete subtyping algorithm is provided, together with a prototype implementation.
Description Affiliation: University of Genoa, Italy (Ancona, Davide; Corradi, Andrea)
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 1983-05-01
Publisher Place New York
Journal ACM SIGPLAN Notices (SIGP)
Volume Number 51
Issue Number 10
Page Count 20
Starting Page 568
Ending Page 587


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Source: ACM Digital Library