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SIGAPL is a Special Interest Group on Array Programming Languages which operates as a sub-group of SIGPLAN (Special Interest Group on Programming Languages) of ACM (Association for Computing Machinery).


SIGAPL was an official special-interest group chartered under the auspices of the ACM (Association for Computing Machinery). In February of 2008 this group was formally de-chartered by the SIG Governing Board.

As part of this change, what was formerly SIGAPL (Special Interest Group on APL) became a chapter within the larger SIGPLAN (Special Interest Group on Programming Languages). One of the goals with this change was to encourage the often quite isolated the APL community to cooperate with with the larger group and thus reach beyond its traditional boundaries. The "APL" part of the acronym was also reinterpreted to cover all array programming languages, not just the original APL language. SIGAPL is now identified as the Special Interest Group on Array Programming Languages.


SIGPLAN arranges the infrequent (but with increasing frequency) HOPL (History of Programming Languages). The first conference (1978), featured Ken Iverson and Adin Falkoff on APL. The fourth conference (2020) features APL again, this time by Morten Kromberg and Roger Hui.

Conference years appear to be given by the expression:

1978 1993 2007 2020 2032 2043 2053 2062 2070 2077 2083 2088 2092 2095 2097 2098
One of HOPL IV's conference badges

HOPL IV conference badge

One of the conference badges for HOPL IV features an APL expression Failed to parse (syntax error): {\displaystyle ÷+\kern{-3pt}/÷(\mathscr E≠0)/\mathscr E} or ÷+/÷(E0)/E which computes multiple aspects of electrical circuits:

÷ +/ ÷ (E0) / E

E is a vector of real numeric values
(E0) produces a Boolean mask indicating which components have a non-zero value
(E0) / E uses the mask to filter the components, thus removing the zeros
÷ finds the reciprocal of those
+/ sums them up
÷ computes the reciprocal of that

The equivalent mathematical formula would be quite involved:

External links


  • SIGPLAN (Special Interest Group on Programming Languages)
  • ACM (Association for Computing Machinery)
  • HOPL (History of Programming Languages conference)


  • SIGAPL (Special Interest Group on Array Programming Languages)
  • SIGPLAN (Special Interest Group on Programming Languages)
  • HOPL IV (fourth conference on the History of Programming Languages)

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