What lies beyond the branch arrow?

ABSTRACT

The question posed in the title could be interpreted as being rhetorical so that its answer would provide a stage to suggest how control flow in user-defined APL functions could be improved. The last thing that APL needs is design by a large committee; there is ample evidence [1] that design by a relatively small group acting by Quaker consensus produces good results. The results have been so pleasing that we may have become myopic in our almost evangelical enthusiasm. Perhaps the time is ripe to take a more critical view of APL in the spirit of constructive criticism. To avoid discussing the issues on the grounds that the Friends are still meeting may not be timely. The area of control flow in a program is one which: (1) continues to receive a great deal of attention in the literature; (2) has provided some sharp criticism of APL from computing professionals; and (3) has produced some variation in the APL community. Summarizing these three directions shall be our objective in the balance of this paper.

REFERENCES

• 1: Falkoff, A.D. and K.E.Iverson (1973), "The Design of APL," IBM Journal of Research and Development 17, 4 (July, 1973), pp. 324-334.
• 2: Edsger W. Dijkstra, The humble programmer, Communications of the ACM, v.15 n.10, p.859-866, Oct. 1972 [doi>10.1145/355604.361591]
• 3: Abrams, P.S. (1973), "Program Writing, Rewriting, and Style," APL Congress 73, North Holland/American Elsevier, p. 1.
• 4: B. M. Leavenworth, Programming with(out) the GOTO, Proceedings of the ACM annual conference, p.782-786, August 01-01, 1972, Boston, Massachusetts, United States [doi>10.1145/800194.805859]
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• 7: "'The GOTO Controversy' Rebuttals and Discussion," (1972) SIGPLAN Notices, 7, 11 (November, 1972), pp. 70-91.
• 8: MCM/70 User's Guide (1974), Micro Computer Machines, Inc., Willowdale, Ontario, Canada, 1974.
• 9: Hassitt, A. and L.E.Lyon (1972), "Efficient Evaluation of Array Subscripts of Arrays," IBM Journal of Research and Development, 16, 1 (January, 1972), pp. 45-57.
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• 16: Harris, L.R. (1973), "A Logical Control Structure for APL," Proceedings of APL Congress '73, North Holland/American Elsevier, Amsterdam, 1973.
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• 22: Brown, J.A. (1971), A Generalization of APL, Ph.D. Dissertation, Syracuse University (September 1971), also available as Technical Report RADC-TR-73-182, Rome Air Development Center (AD 770 488/5WC) (January 1973).

INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.2 Language Classifications

          Nouns: APL

Additional Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.3 Language Constructs and Features

General Terms:
Languages