Author name cluster

J. Palsberg

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

3 papers

1 author row

I&C Journal 1995 Journal Article

Efficient Inference of Object Types

J. Palsberg

M. Abadi and L. Cardelli have recently investigated a calculus of objects (1994). The calculus supports a key feature of object-oriented languages: an object can be emulated by another object that has more refined methods. Abadi and Cardelli presented four first-order type systems for the calculus. The simplest one is based on finite types and no subtyping, and the most powerful one has both recursive types and subtyping. Open until now is the question of type inference, and in the presence of subtyping "the absence of minimum typings poses practical problems for type inference. " In this paper, we give an O(n 3) algorithm for each of the four type inference problems and we prove that all the problems are P-complete. We also indicate how to modify the algorithms to handle functions and records.

Details DOI

I&C Journal 1995 Journal Article

Safety Analysis versus Type Inference

J. Palsberg
M.I. Schwartzbach

Safety analysis is an algorithm for determining if a term in an untyped lambda calculus with constants is safe, i. e. , if it does not cause an error during evaluation. This ambition is also shared by algorithms for type inference. Safety analysis and type inference are based on rather different perspectives, however. Safety analysis is global in that it can only analyze a complete program. In contrast, type inference is local in that it can analyze pieces of a program in isolation. In this paper we prove that safety analysis is sound, relative to both a strict and a lazy operational semantics. We also prove that safety analysis accepts strictly more safe lambda terms than does type inference for simple types. The latter result demonstrates that global program analyses can be more precise than local ones.

Details DOI

I&C Journal 1994 Journal Article

A Denotational Semantics of Inheritance and Its Correctness

W. Cook
J. Palsberg

This paper presents a denotational model of inheritance. The model is based on an intuitive motivation of inheritance as a mechanism for deriving modified versions of recursive definitions. The correctness of the model is demonstrated by proving it equivalent to an operational semantics of inheritance based upon the method lookup algorithm of object-oriented languages.

Details DOI