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HOPL IV published
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The '''History of Programming Languages conference''' is held by [[wikipedia:SIGPLAN|SIGPLAN]] to discuss and record the history of programming language development. It is notable to APL historians because of the very detailed papers presented at the 1978 and 2020 conferences. [[wikipedia:ACM|ACM]] SIGPLAN is the Special Interest Group on Programming Languages; while [[SIGAPL]] is a chapter of SIGPLAN, it is not directly associated with HOPL. | |||
To date, there have been four HOPL conferences: they are held infrequently, but with increasing frequency. The first, in 1978, featured a presentation by [[Ken Iverson]] and [[Adin Falkoff]] on APL.<ref>[[Adin Falkoff]], and [[Ken Iverson]]. [https://dl.acm.org/doi/abs/10.1145/960118.808372 ''The Evolution of APL''] ([https://www.jsoftware.com/papers/APLEvol.htm web]). ACM SIGPLAN Notices, Volume 13, Number 8. 1978-08.</ref> The fourth conference, in 2020, features an APL presentation again, this time by [[Roger Hui]] and [[Morten Kromberg]].<ref>[[Roger Hui]] and [[Morten Kromberg]]. [https://dl.acm.org/doi/abs/10.1145/3386319 ''APL since 1978'']. ACM HOPL IV. 2020-06.</ref> | |||
Conference years appear to be given by the expression: | |||
<source lang=apl> | |||
1962++\⌽⍳16 | |||
1978 1993 2007 2020 2032 2043 2053 2062 2070 2077 2083 2088 2092 2095 2097 2098 | |||
</source> | |||
[[File:BadgeAPL.png|thumb|right|One of HOPL IV's conference badges]] | |||
=== HOPL IV conference badge === | |||
One of the conference badges for HOPL IV features an APL expression <math>\div+\!/\div(\mathcal E \ne 0)/\mathcal E</math> or <source lang=apl inline>÷+/÷(E≠0)/E</source> which computes multiple aspects of electrical circuits: | |||
{| | |||
|<source lang=apl inline>÷</source>||<source lang=apl inline>+/</source>||<source lang=apl inline>÷</source>||<source lang=apl inline>(E≠0)</source>||<source lang=apl inline>/</source>||<source lang=apl inline>E</source> | |||
|- | |||
| colspan=6|<hr/> | |||
|- | |||
|||||||||||<source lang=apl inline>E</source>||is a vector of real numeric values | |||
|- | |||
|||||||<source lang=apl inline>(E≠0)</source>||||||produces a Boolean mask indicating which components have a non-zero value | |||
|- | |||
|||||||<source lang=apl inline>(E≠0)</source>||<source lang=apl inline>/</source>||<source lang=apl inline>E</source>||uses the mask to filter the components, thus removing the zeros | |||
|- | |||
|||||<source lang=apl inline>÷</source>||||||||finds the reciprocal of those | |||
|- | |||
|||<source lang=apl inline>+/</source>|||||||||||sums them up | |||
|- | |||
|<source lang=apl inline>÷</source>||||||||||||computes the reciprocal of that | |||
|} | |||
The equivalent mathematical formula would be quite involved: | |||
:<math>1\over\displaystyle\sum_{i=1}^n\frac1{E_i}[E_i\neq 0]</math> | |||
== External links == | |||
* [[wikipedia:HOPL|HOPL]] | |||
* [http://www.sigplan.org/ SIGPLAN] website | |||
* [https://hopl4.sigplan.org/ HOPL IV] website | |||
== References == | |||
<references /> | |||
{{APL community}}[[Category:APL history]][[Category:Conferences]][[Category:Publications]] | |||