Remembering Ken Iverson
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Collection: Alexa Crawls
Starting in 1996, Alexa Internet has been donating their crawl data to the Internet Archive. Flowing in every day, these data are added to the Wayback Machine after an embargo period.
TIMESTAMPS
The Wayback Machine - https://web.archive.org/web/20180412035431/http://keiapl.org:80/rhui/remember.htm
Remembering Ken Iverson
by Roger Hui, November 2004
Acknowledgments
I am indebted to Chris Burke, Eric Iverson, Eugene McDonnell,<br>Donald McIntyre, Roland Pesch, Joey Tuttle, and Arthur Whitney<br>for reading earlier drafts of the paper.
0. Beginnings
I first met Ken Iverson early in 1981 in Toronto, when he invited me<br>to dinner, along with Mrs. Jean Iverson, and Eugene McDonnell, Lib Gibson,<br>David Keith, and Jane Minett of I.P. Sharp Associates.<br>I believe the dinner happened because Eugene mentioned<br>me to Ken, mainly due to The N Queens Problem paper<br>[0]<br>I had submitted to the Recreational APL column that he wrote and edited.
So now not only was I to meet the great Ken Iverson,<br>inventor of APL, but I was also to get a free dinner.<br>The latter was a consideration: at the time<br>I was a graduate student at the University of Toronto.<br>At the appointed hour I went up to Ken’s apartment on the<br>47th floor of the Manulife Center.<br>I was so in awe of the great man that I took scant notice of<br>the spectacular view—from the apartment one can see Niagara Falls,<br>a 90 minute drive away—until Ken directed me to do so.
We then went for dinner at a restaurant on King Street.<br>I don’t remember much about the dinner,<br>except for the way Ken left the tip.<br>The change came back from paying the dinner check, in the form of<br>the dingiest looking bills you ever saw. Ken took out his wallet,<br>extracted some crisp clean bills, and crumbled them up before<br>leaving them on the tray.
In another sense, I had “met” Ken Iverson years before,<br>when I learned APL during my undergraduate studies<br>at the University of Alberta, from reading the<br>APL\360 User’s Manual<br>[1]<br>and from working at the computer terminal.<br>Since I did not have direct access to Ken,<br>I read his papers carefully, principally<br>The Design of APL<br>[2],<br>The Evolution of APL<br>[3], and<br>Notation as a Tool of Thought<br>[4].<br>I also further acquainted myself with APL<br>during the summers of 1975 and 1976,<br>when Lib Gibson hired me to work as a summer student<br>at I.P. Sharp in Calgary.
1. From APL to J
The late 70’s and early 80’s were an exciting time for APL.<br>APL was a commercial success. APL was taught in schools and<br>universities. APL conferences were well-attended.<br>(I attended my first APL conference in 1979 in Rochester,<br>and my recollected impression<br>is that the parallel sessions at the conference each had audiences<br>of over a hundred.)
Ken had published his seminal paper Operators and Functions<br>[5]<br>in April 1978.<br>He went from IBM to I.P. Sharp in Toronto in 1980,<br>and there collaborated with Arthur Whitney on<br>Practical Uses of a Model of APL<br>[6]<br>in 1981-82, leading to Rationalized APL<br>[7]<br>in January 1983, multiple editions of<br>A Dictionary of the APL Language between 1984 and 1987,<br>and A Dictionary of APL<br>[8]<br>in September 1987. Within I.P. Sharp,<br>the phrase “dictionary APL” came into use to denote the APL<br>specified by A Dictionary of APL, itself referred<br>to as “the dictionary”.
At that time, the main APL vendors were IBM, STSC,<br>and I.P. Sharp, and all were active in developing and<br>extending the language.<br>IBM had APL2, based on the work of Trenchard More and Jim Brown<br>[9,<br>10,<br>11].<br>Work on APL2 proceeded intermittently for 15 years<br>[12],<br>with actual coding starting in 1971 and<br>APL2 becoming available as an IUP in 1982.<br>STSC had an experimental APL implementation called NARS<br>[13].<br>NARS and APL2 differed in fundamental respects<br>from dictionary APL (and differed from each other).
I.P. Sharp implemented the new APL ideas in stages,<br>complex numbers, enclosed (boxed) arrays, match, and composition operators<br>(on, over, under) in 1981<br>[14,<br>15],<br>determinant in 1982<br>[16],<br>and the rank operator, lev (left),<br>dex (right), and link in 1983<br>[17].<br>However, the domains of operators<br>were restricted to the primitive functions or subsets thereof.<br>I.P. Sharp also had SHARP APL/HP<br>[18],<br>principally the work of Arthur Whitney with the<br>assistance of Rob Hodgkinson.
An important stepping stone from APL to J was SAX<br>[19],<br>SHARP APL/Unix, written in C and based on an implementation by STSC.<br>An alpha version of SAX became available within I.P. Sharp<br>around December 1986 or early 1987. From that time to August 1989,<br>when the first J source line was written,<br>I had access to SAX, and...