Higher-Order and Symbolic Computation, 12(1)5

Editorial

Olivier Danvy and Carolyn Talcott

This issue of HOSC is the second of a two-part series dedicated to the general topic ofcontinuations. The first part appeared as HOSC 11(2). This series grew out of CW'97, the second ACM Workshop on Continuations, which took place in Paris, France on January14th, 1997 [1].

The notion of continuation is ubiquitous in many different areas of computer science,including logic, constructive mathematics, programming languages, and programming. CW'97 aimed at providing a forum for discussion of new results and work in progress; work aimed at a better understanding of the nature of continuations; applications of continuations; and the relation of continuations to other areas of logic and computer science.

The articles in this special issue reflect this diversity. At the 1988 Lisp conference [2], William Clinger, Anne Hartheimer, and Erik Ost presented the first comprehensive overview of how to implement first-class continuations. We are pleased to see the journal version of their presentation here.

Among the properties of first-class continuations is that they may be invoked more than once. But which computational power does this ability correspond to, and how does it affect reasoning about programs? Both of these issues are investigated in Hayo Thielecke's article.

Exceptions are seemingly less expressive than continuations because they only allow one to terminate some computations prematurely. That this is not always the case was shown by Mark Lillibridge in 1995 and documented in a technical report [3]. His contribution to this volume is a much revised and expanded version of this technical report.

We conclude with an overview of earlier work done in Erik Sandewall's research group, which contributed both to continuations, to partial evaluation, and to the representation of first-class functions.

References

1. Olivier Danvy, editor. Proceedings of the Second ACM SIGPLAN Workshop on Continuations, Technical report BRICS-NS-96-13, Department of Computer Science, University of Aarhus, Aarhus, Denmark, January 1997.

2. William Clinger, Anne H. Hartheimer, and Eric M. Ost. Implementation strategies for continuations. In Robert (Corky) Cartwright, editor, Proceedings of the 1988 ACM Conference on Lisp and Functional Programming, pages 124-131, Snowbird, Utah, July 1988. ACM Press.

3. Mark Lillibridge. Exceptions are strictly more powerful than call/cc. Technical Report CMU-CS-95-178, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania, July 1995.
[picture of journal cover]

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