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Indexing and indexed replacement in APL

Author:

Roland H. PeschAuthors Info & Claims

ACM SIGAPL APL Quote Quad, Volume 12, Issue 1

Pages 258 - 261

https://doi.org/10.1145/390007.805370

Published: 01 September 1981 Publication History

Abstract

Indexing and indexed replacement have an exceptional syntax. Enclosed arrays make this syntax unnecessary. An operator with an ambivalent derived function is proposed as the solution. The monadic case performs selection; the dyadic case, replacement.

References

[1]

The term 'list' is an informal one, yet there seems to be no other name for this sort of expression. See APL Language (IBM GC26-3847-4, July 1978),p. 54; and Paul Berry, Sharp APL Reference Manual (I.P. Sharp Associates, March 1979), pp. 48-49, 155-156.

[2]

Kenneth E. Iverson, A Programming Language (Wiley; New York, 1962), pp. 11-12.

Digital Library

[3]

Kenneth E. Iverson, 'Formalism in Programming Languages' in Communications of the ACM (Vol. 7, No. 2, Feb. 1964), p. 81, already uses the one-symbol notation.

Digital Library

[4]

This corresponds to the implementation described by Robert Bernecky and Kenneth E. Iverson, 'Operators and Enclosed Arrays' in the APL Users Meeting Proceedings (I.P. Sharp Associates; Toronto, 1980), pp. 319-320. My proposal for an indexing operator, however, is independent of the particular flavor of enclosed arrays used. Its definition remains the same regardless of the kind of enclose and disclose used.

[5]

Ziad Ghandour and Jorge Mezei, 'General Arrays, Operators and Functions' (IBM J. Res. Develop., July 1973) p. 337

[6]

Bernecky and Iverson, op. cit., pp. 320-321

[7]

For example, using the index operator proposed here with Bernecky and Iverson's ö (on) operator, A{Z;;} could be written as (<Z)Iö0 A

[8]

Index origin 0 is assumed throughout this paper.

[9]

James A. Brown, A Generalization of APL (Doctoral Thesis, 1971, Dept. of Systems and Information Sciences, Syracuse University, New York) pp. 142-146

[10]

Berry, op. cit., p. 169; A.D. Falkoff and D.L. Orth, 'Development of an APL Standard', APL79 Conference Proceedings, Part 2 (ACM; Rochester, 1979), p. 437

[11]

Although the English text in the Falkoff/Orth paper quoted in {9} describes assignment as a function, the formal definition in the same paper (p. 422) singles out assignment, treating it separately from all the other primitives.

[12]

see for example the descriptions of assignment and indexed assignment in Falkoff and Orth, op. cit., p. 436-437, and Berry, op. cit., p. 169-170

[13]

E.E. McDonnell, 'MASK and MESH' (APL Workshop, Syracuse University, Minnowbrook, NY; 1980). McDonnell points out that his proposal is descended from definitions of mask and mesh in Iverson's A Programming Language.

[14]

James E. Lucas also has work in progress including proposals for similar extensions to other selection functions.

[15]

Strand notation advocates would have to write, instead, USE X (II)A and USE X(U/) Y

[16]

M.A. Jenkins and J. Michel, 'Operators in an APL Containing Nested Arrays' (Quote Quad, vol. 9, no.2, December 1978), p. 19

Digital Library

[17]

The model is available in the workspace 2035692 INDEXO on the I.P. Sharp APL system. Since it invokes @@@@, the version of the model in that workspace differs from that in this paper in that names start with one underbarred character. This allows users of the model to avoid harming it by limiting their use of names to non-underbarred characters.

Cited By

Gerth JOrth D(1987)Indexing and merging in APLProceedings of the international conference on APL10.1145/55626.55646(156-161)Online publication date: 1-Dec-1987
https://dl.acm.org/doi/10.1145/55626.55646
Gerth JOrth D(1987)Indexing and merging in APLACM SIGAPL APL Quote Quad10.1145/377719.5564618:2(156-161)Online publication date: 1-Dec-1987
https://dl.acm.org/doi/10.1145/377719.55646
Iverson KWhitney ABergen MJanko WKöhler CWaller K(1982)Practical uses of a model of APLProceedings of the international conference on APL10.1145/800071.802236(140-145)Online publication date: 26-Jul-1982
https://dl.acm.org/doi/10.1145/800071.802236
Show More Cited By

Index Terms

Indexing and indexed replacement in APL
1. Software and its engineering
  1. Software notations and tools
    1. General programming languages
      1. Language types
2. Theory of computation
  1. Formal languages and automata theory
    1. Grammars and context-free languages

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Published In

cover image ACM SIGAPL APL Quote Quad

ACM SIGAPL APL Quote Quad Volume 12, Issue 1

September 1981

354 pages

ISSN:0163-6006

DOI:10.1145/390007

Issue’s Table of Contents

APL '81: Proceedings of the international conference on APL
October 1981
354 pages
ISBN:0897910354
DOI:10.1145/800142
Chairman:
Richard J. Orgass,
Editors:
William L. Anderson,
David G. Smith

Copyright © 1981 Author.

Publisher

Association for Computing Machinery

New York, NY, United States

Publication History

Published: 01 September 1981

Published in SIGAPL Volume 12, Issue 1

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Cited By

Gerth JOrth D(1987)Indexing and merging in APLProceedings of the international conference on APL10.1145/55626.55646(156-161)Online publication date: 1-Dec-1987
https://dl.acm.org/doi/10.1145/55626.55646
Gerth JOrth D(1987)Indexing and merging in APLACM SIGAPL APL Quote Quad10.1145/377719.5564618:2(156-161)Online publication date: 1-Dec-1987
https://dl.acm.org/doi/10.1145/377719.55646
Iverson KWhitney ABergen MJanko WKöhler CWaller K(1982)Practical uses of a model of APLProceedings of the international conference on APL10.1145/800071.802236(140-145)Online publication date: 26-Jul-1982
https://dl.acm.org/doi/10.1145/800071.802236
Iverson KWhitney A(1982)Practical uses of a model of APLACM SIGAPL APL Quote Quad10.1145/390006.80223613:1(140-145)Online publication date: 26-Jul-1982
https://dl.acm.org/doi/10.1145/390006.802236
Hui RKromberg M(2020)APL since 1978Proceedings of the ACM on Programming Languages10.1145/33863194:HOPL(1-108)Online publication date: 12-Jun-2020
https://dl.acm.org/doi/10.1145/3386319
Ruehr KBergen MJanko WKöhler CWaller K(1982)A survey of extensions to APLProceedings of the international conference on APL10.1145/800071.802257(277-314)Online publication date: 26-Jul-1982
https://dl.acm.org/doi/10.1145/800071.802257
Chastney PBergen MJanko WKöhler CWaller K(1982)The hunting of the SnarkProceedings of the international conference on APL10.1145/800071.802224(72-77)Online publication date: 26-Jul-1982
https://dl.acm.org/doi/10.1145/800071.802224
Ruehr K(1982)A survey of extensions to APLACM SIGAPL APL Quote Quad10.1145/390006.80225713:1(277-314)Online publication date: 26-Jul-1982
https://dl.acm.org/doi/10.1145/390006.802257
Chastney P(1982)The hunting of the SnarkACM SIGAPL APL Quote Quad10.1145/390006.80222413:1(72-77)Online publication date: 26-Jul-1982
https://dl.acm.org/doi/10.1145/390006.802224

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