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19
Inheritance As Implicit Coercion
 Information and Computation
, 1991
"... . We present a method for providing semantic interpretations for languages with a type system featuring inheritance polymorphism. Our approach is illustrated on an extension of the language Fun of Cardelli and Wegner, which we interpret via a translation into an extended polymorphic lambda calculus. ..."
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Cited by 116 (3 self)
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. We present a method for providing semantic interpretations for languages with a type system featuring inheritance polymorphism. Our approach is illustrated on an extension of the language Fun of Cardelli and Wegner, which we interpret via a translation into an extended polymorphic lambda calculus. Our goal is to interpret inheritances in Fun via coercion functions which are definable in the target of the translation. Existing techniques in the theory of semantic domains can be then used to interpret the extended polymorphic lambda calculus, thus providing many models for the original language. This technique makes it possible to model a rich type discipline which includes parametric polymorphism and recursive types as well as inheritance. A central difficulty in providing interpretations for explicit type disciplines featuring inheritance in the sense discussed in this paper arises from the fact that programs can typecheck in more than one way. Since interpretations follow the type...
Efficient Type Inference for HigherOrder BindingTime Analysis
 In Functional Programming and Computer Architecture
, 1991
"... Bindingtime analysis determines when variables and expressions in a program can be bound to their values, distinguishing between early (compiletime) and late (runtime) binding. Bindingtime information can be used by compilers to produce more efficient target programs by partially evaluating prog ..."
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Cited by 91 (4 self)
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Bindingtime analysis determines when variables and expressions in a program can be bound to their values, distinguishing between early (compiletime) and late (runtime) binding. Bindingtime information can be used by compilers to produce more efficient target programs by partially evaluating programs at compiletime. Bindingtime analysis has been formulated in abstract interpretation contexts and more recently in a typetheoretic setting. In a typetheoretic setting bindingtime analysis is a type inference problem: the problem of inferring a completion of a λterm e with bindingtime annotations such that e satisfies the typing rules. Nielson and Nielson and Schmidt have shown that every simply typed λterm has a unique completion ê that minimizes late binding in TML, a monomorphic type system with explicit bindingtime annotations, and they present exponential time algorithms for computing such minimal completions. 1 Gomard proves the same results for a variant of his twolevel λcalculus without a socalled “lifting ” rule. He presents another algorithm for inferring completions in this somewhat restricted type system and states that it can be implemented in time O(n 3). He conjectures that the completions computed are minimal.
Programming with Intersection Types and Bounded Polymorphism
, 1991
"... representing the official policies, either expressed or implied, of the U.S. Government. ..."
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Cited by 66 (4 self)
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representing the official policies, either expressed or implied, of the U.S. Government.
A Record Calculus Based on Symmetric Concatenation
 In Proc. of the ACM Symp. on Principles of Programming Languages
, 1991
"... Type systems for operations on extensible records form a foundation for statically typed languages addressing some aspects of object oriented programming and database applications. A number of primitive operations have been proposed: extending a record with a new field, overwriting an existing field ..."
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Cited by 58 (2 self)
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Type systems for operations on extensible records form a foundation for statically typed languages addressing some aspects of object oriented programming and database applications. A number of primitive operations have been proposed: extending a record with a new field, overwriting an existing field, removing a field, and various kinds of concatenation. We show here that a record calculus based on a symmetric concatenation operator, where two records may be concatenated only if they have no overlapping fields, also captures the types of many other useful primitive record operations. "Mergeability constraints" are expressed directly using explicit annotations on type variables and constrained secondorder type quantification instead of a rule of subsumption; we argue that the resulting system is more straightforward than subsumptionbased alternatives. This research was supported in part by the Office of Naval Research and in part by the Defense Advanced Research Projects Agency (DOD), ...
ML With Extended Pattern Matching And Subtypes
, 1989
"... We extend a fragment of the programming language ML by incorporating a more general form of record pattern matching and providing for userdeclared subtypes. Together, these two enhancements may be used to support a restricted objectoriented programming style. In keeping with the framework of ML, w ..."
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Cited by 44 (2 self)
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We extend a fragment of the programming language ML by incorporating a more general form of record pattern matching and providing for userdeclared subtypes. Together, these two enhancements may be used to support a restricted objectoriented programming style. In keeping with the framework of ML, we present typing rules for the language, and develop a type inference aJgorithm. We prove that the algorithm is sound with respect to the typing rules, and that it infers a most general typing for every typable expression.
Principal Type Schemes for Functional Programs with Overloading and Subtyping
 Science of Computer Programming
, 1994
"... We show how the Hindley/Milner polymorphic type system can be extended to incorporate overloading and subtyping. Our approach is to attach constraints to quantified types in order to restrict the allowed instantiations of type variables. We present an algorithm for inferring principal types and ..."
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Cited by 44 (1 self)
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We show how the Hindley/Milner polymorphic type system can be extended to incorporate overloading and subtyping. Our approach is to attach constraints to quantified types in order to restrict the allowed instantiations of type variables. We present an algorithm for inferring principal types and prove its soundness and completeness. We find that it is necessary in practice to simplify the inferred types, and we describe techniques for type simplification that involve shape unification, strongly connected components, transitive reduction, and the monotonicities of type formulas.
Typed Sets as a Basis for ObjectOriented Database Schemas
, 1993
"... The objectoriented data model TM is a language that is based on the formal theory of FM, a typed language with objectoriented features such as attributes and methods in the presence of subtyping. The general (typed) set constructs of FM allow one to deal with (database) constraints in TM. The pap ..."
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Cited by 28 (6 self)
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The objectoriented data model TM is a language that is based on the formal theory of FM, a typed language with objectoriented features such as attributes and methods in the presence of subtyping. The general (typed) set constructs of FM allow one to deal with (database) constraints in TM. The paper describes the theory of FM, and discusses the role that set expressions may play in conceptual database schemas. Special attention is paid to the treatment of constraints, and a threestep specification approach is proposed. This approach results in the formal notion of database universe stated as an FM expression.
Effect Systems with Subtyping
"... Effect systems extend classical type systems with effect information. Just as types describe the possible values of expressions, effects describe their possible evaluation behaviors. Effects, which appear in function types, introduce new constraints on the typability of expressions. To increase the ..."
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Cited by 9 (0 self)
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Effect systems extend classical type systems with effect information. Just as types describe the possible values of expressions, effects describe their possible evaluation behaviors. Effects, which appear in function types, introduce new constraints on the typability of expressions. To increase the exibility and accuracy of e ect systems, we present a new effect system based on subtyping. The subtype relation is induced by a subsumption relation on effects. This subtyping effect system avoids merging effect information together, thus collecting more precise effect information. We introduce a reconstruction algorithm which for any expression already typed with classical types, reconstructs its type and effect based on the subtype relation. The reconstruction algorithm is sound and complete w.r.t. the static semantics.
A Study of Semantics, Types, and Languages for Databases and Object Oriented Programming
, 1989
"... The purpose of this thesis is to investigate a type system for databases and objectoriented programming and to design a statically typed programming language for these applications. Such a language should ideally have a static type system that supports: • polymorphism and static type inference, • r ..."
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Cited by 8 (0 self)
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The purpose of this thesis is to investigate a type system for databases and objectoriented programming and to design a statically typed programming language for these applications. Such a language should ideally have a static type system that supports: • polymorphism and static type inference, • rich data structures and operations to represent various data models for databases including the relational model and more recent complex object models, • central features of objectoriented programming including user definable class hierarchies, multiple inheritance, and data abstraction, • the notion of extents and objectidentities for objectoriented databases. Without a proper formalism, it is not obvious that the construction of such a type system is possible. This thesis attempts to construct one such formalism and proposes a programming language that uniformly integrate all of the above features. The specific contributions of this thesis include: • A simple semantics for ML polymorphism and axiomatization of the equational theory of ML. • A uniform generalization of the relational model to arbitrary complex database objects that
The Typed Polymorphic LabelSelective λCalculus
 IN PROC. ACM SYMPOSIUM ON PRINCIPLES OF PROGRAMMING LANGUAGES
, 1994
"... Formal calculi of record structures have recently been a focus of active research. However, scarcely anyone has studied formally the dual notioni.e., argumentpassing to functions by keywords, and its harmonization with currying. We have. Recently, we introduced the labelselective calculus, a ..."
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Formal calculi of record structures have recently been a focus of active research. However, scarcely anyone has studied formally the dual notioni.e., argumentpassing to functions by keywords, and its harmonization with currying. We have. Recently, we introduced the labelselective calculus, a conservative extension of calculus that uses a labeling of abstractions and applications to perform unordered currying. In other words, it enables some form of commutation between arguments. This improves program legibility, thanks to the presence of labels, and efficiency, thanks to argument commuting. In this paper, we propose a simply typed version of the calculus, then extend it to one with MLlike polymorphic types. For the latter calculus, we establish the existence of principal types and we give an algorithm to compute them. Thanks to the fact that labelselective calculus is a conservative extension of calculus by adding numeric labels to stand for argument positions, its...