Clear, Firm, Intelligent, Decisive, Kind and Gentle

Roger would have been seriously annoyed by all this: a whole lot of people talking and writing about him, rather than concentrating on important work that has been done, or needs to be done. He did everything he could to downplay the seriousness of his condition and keep it from becoming a topic or otherwise interfering with his duties at work or at home. But now that he has headed off to present his code to the Galactic Emperor, I hope that we can all be forgiven for needing to share our feelings of loss: he left us much too soon.

I read the words in the title above in a message written by Rob Hodgkinson on the Jprogramming forum [Jprogramming] Roger Hui – 1953 – 2021 (, and I cannot think of a more fitting description of Roger, so I hope Rob will approve my reuse here.

I expect that almost everyone who worked with Roger would agree on the first four; I suspect a few people may occasionally have experienced the “Firm and Decisive” aspects of some e-mail communication as less than Kind and Gentle. In his post, Rob does go on to say “funny how that reminds me of both Ken and Roger alike”. As was the case with Ken Iverson, arguing with Roger always carried the risk, if you were not careful enough with the rope that was extended to you, of exposing that you hadn’t quite thought your arguments through.

Roger at Dyalog

Although Rob, Roger and all worked for I.P.Sharp associates back in the 1980’s, we were almost perfectly distributed around the globe at 12°E, 151°E and 122°W. I did not have an opportunity to work with Roger until he sent me a message with the subject line “business proposition” in 2008, proposing that he do some work for Dyalog. Obviously, we leapt at the chance, and enjoyed a very productive period at Dyalog, with the combined intellect of Roger and John Scholes guiding our work on language, before they both departed prematurely.

With Roger’s help, we were able to bring many of the ideas that he and Ken had worked on in J into Dyalog APL, and start to repair some of the wounds that opened up when the community split in two around 1983. Much to my surprise, Roger took an immediate liking to Scholes’ dfns, and the combined efforts of Scholes and Hui have been an important part of creating a foundation for APL to grow again, as a modern programming language. A joint presentation by John and Roger on “Potential Version 14.0 Features” demonstrates the results of some of this work.

Roger and Ken

As Ken started on J, he had Roger at his side to provide the clear, firm, intelligent, decisive, kind and gentle feedback – and the exceptional programming skills – that Dick Lathwell, Roger Moore, Adin Falkoff, Phil Abrams and Larry Breed had provided for the first APL implementation back in 1966. Although I was nowhere close to either of these projects, there is no doubt in my mind that this work made the difference between having a collection of very interesting ideas, and having tools that thousands of people decided to use to solve problems that were important to them.

Roger the Archiver

In addition to being intelligent and spending a great amount of time thinking about things, I believe that a key to his ability to be clear, firm and decisive was that Roger was extremely well read. He was familiar with a huge amount of significant writing about array languages.

Roger clearly felt this was important and tried hard to help the rest of us to benefit. Apart from code that he wrote, and the excellent documents that he authored himself, one of the most significant contributions that Roger has made to the community is his collection of digitized historical documents that have been made available on the jsoftware website, such as Community/Creative Commons – J Wiki (

As the doctors started to give him estimates for his remaining time, Roger ramped up his own writing and his work on collecting the writings of others. His biggest project was the paper on “APL Since 1978”, written for the fourth conference on the History of Programming Languages. I’m extremely happy to be listed as a co-author of this paper, but 90% of the work – and nearly all the serious content about the evolution of the language – was provided by Roger. Fortunately, Roger was still well enough in June of this year to be able to do an energetic presentation of this work.

Shortly after the HOPL IV conference, Roger’s health started to deteriorate. I was extremely lucky that the Canadian border was opened to fully vaccinated visitors at the start of September, which made it possible for me to visit Roger and do my best to thank him for his enormous contributions – and also ask whether there were any unfinished tasks we needed to take care of, such as archiving more documents.

According to Roger, it is done. Knowing his level of determination and dedication to any task that he took upon himself, we can probably rely on that. Roger frequently used the acronym “WWKD” (What Would Ken Do?) in discussions. Possibly, Roger ended up being better at answering that question than Ken himself. Now we also need to ask WWRD? Fortunately, Roger has done his best to help us find the answers.

We just need to start reading and get to work!

Humourous Gourmet

If I was going to add a couple of words to Rob’s list, it would be these two. Humour is very often the companion of intelligence, and this was definitely true for Roger. In addition to the collection of serious material, Roger was keen to collect humourous content related to his work and his colleagues, such as APL Quotations and Anecdotes ( The subject line in his first message to me in 2008 (“business proposition”) was clearly a joke, and a dangerous one: if it had not all been in lowercase, I could easily have deleted it unread.

Roger was also a bit of a gourmet, and discovered that he shared this interest with Gitte Christensen, who enjoys cooking delicious meals for the inhabitants of the 5-bedroom house that Dyalog rents in Basingstoke, which until the pandemic was frequently full of visitors from distant places.

When I visited Roger and came home with his final input on my to do list (and perhaps more importantly, my NOT-to-do list). He also provided Gitte with a couple of his favourite recipes. I’m looking forward to remembering Roger by tasting the results!

Roger’s presentations often included jokes, but they were often so dry and sophisticated that they sailed over the heads of most of the audience. His daughter Rachel suggested that he try injecting some more “regular” jokes into his talks. I’m not sure whether that is the reason why Roger also published a collection of the Jokes We Told Each Other (

From the collection, we can see that Roger and Rachel had been working on each other for some time:

What does Silly Billy call his pet leopard? Stripes!
Now, what does Silly Jilly call her pet zebra?
When my daughter Rachel was about 4 years old, I asked her this, in that sequence, and to my gratification she answered without hesitation, Spot!

– Morten Kromberg, Dyalog

Arthur Whitney


A: i got a job for roger at morgan stanley — maybe 1989?
on his first day — at the end of the day — he realized his wallet was missing.
we went out to avenue of the americas and found it on the street — all there.

B: when roger was 12 his family moved from hong kong to edmonton. (his dad was a cook)
decades later i asked roger if he does math in cantonese or english.
he smiled:  cantonese

cantonese can count from 0 to 9 much faster than english.
cantonese can do arithmetic by sound (we can’t). e.g. 13+24 in cantonese is: 1-ten 3 plus 2-ten 4

Chris Burke


I knew Roger for more than 30 years, first at IP Sharp and then working with him at Jsoftware. It was a great privilege to be part of the J team with Ken and Roger.

When I think of his life’s work, it is not just for the development of J and APL systems, but also for an outstanding collection of Essays and Papers that Roger worked on quietly for many years, right up to the end. His Essays alone were a major reason why the J wiki became so successful. Many a time I referred to them to see how Roger would solve a problem. A recent effort that reflects his deep understanding of APL is the HOPL 4 paper on “APL since 1978”, jointly written with Morten.

Despite his outsized talent, he was easy-going, modest and unassuming with others. He and his family became friends. We were fortunate to live reasonably close both in Toronto and Vancouver and in recent years we were able to meet up at his home, or for dimsum at his favorite restaurant. He enjoyed games and was a mean scrabble player. My son shared his birthday and they always exchanged greetings. He will be sadly missed by all our family.

Henry Rich


I shared only a few words with Roger face to face, but we exchanged hundreds of emails. They were almost all technical, so it is as a programmer that I remember him. No one has influenced me more than Roger.

I encountered Roger when we were both in our early forties. By that time I had developed a very high opinion of my own programming ability, but as the years went by it became clear that Roger used APL/J with greater skill than I could achieve. He said it was just practice, but after many years of continued practice I have to differ.

As it turned out, I took over the code for Roger’s J interpreter about 5 years ago, and have spent most of my time since working on it. Surely no one has studied Roger’s code more deeply than I have. It is characterized by elegance, brevity, and perfection. The design matches the need perfectly, without exceptional cases. The coding has a minimum of repetition owing to the use of a very well-designed set of macros and by implementing many operations in J itself. Each individual function is coded in just the right order, with no wasted effort.

Even as parts of the J interpreter are recoded for modern CPU architectures, Roger’s design remains as sound as ever. It is said that no man is a hero to his valet. Well, in programming terms I am Roger’s valet, and he’s still a hero to me.

Joshua David


From complex language design discussions to extraordinary puns, Roger’s emails never failed to entertain. Roger was able to anticipate and provide blueprints to problems that felt impossible to wrap your head around. I didn’t have decades of a close relationship with him, and I’m sure there are others out there who wish they knew him more closely. In one of his last forum posts, Roger left a blueprint for this exact problem. He describes how much of what he knew of Ken Iverson came from thoroughly studying and reading Ken’s papers, not just from apprenticing with him in person.

Luckily, Roger also left behind a wealth of papers, essays, and code snippets. They are a stunning display of the mind of Roger. He frequently spoke of writing monument-quality code. Again, Roger’s code is the blueprint for this: a perfect blend of beautiful code that achieves optimal performance. Even though his technical achievements were gargantuan, a very important aspect of his life was his personal character. He attributed a lot his skill to his apprenticeship with Ken. A less obvious benefit of the apprenticeship that he spoke about was how his entire life benefited from absorbing some qualities of Ken.

I think anyone who knew Roger can say the same for him. You can get a good sense of Roger’s character from reading the work he left behind. We are enormously privileged for everything he did for the community. No doubt about it, his thoughts will continue to steer the development of array languages well into the future.

Ron Murray


During the past year working closely with Roger, I got to know him and appreciate his insights about writing correct algorithms and testing them completely. He often spoke of writing “monument quality” code that would be immortal.  He cared deeply about that. He also had a keen sense of humor. So when I mentioned that he could become immortal by just not dying, he immediately recognized that as one of Woody Allen’s lines, and laughed.

I will miss him deeply.

Fiona Smith


It was easy to underestimate the genius behind Roger’s unassuming exterior. He never flaunted his abilities and achievements, but I soon learned to really listen when he started speaking. Professionally, every word was carefully chosen to convey precise information with maximum clarity and the minimum of fuss; personally, there lurked a gentle sense of humour that delighted in sneaking puns and witticisms into conversation and seeing whether people detected them (his “APL Puns” blog post is a great example of his badinage). Roger often joked that his first encounter with APL was as a child when he entered Canada aboard an American President Lines ship – I heard him relay this to each new starter at Dyalog Ltd, and each time it made him smile!

The public face of his illness was one of grace and strength. Only a few weeks ago he emailed me with a recommendation for a film he’d seen that he thought I might enjoy (I had already seen it and yes, I had enjoyed it, so he was correct in his assessment). No fuss, no drama, just Roger.

One of my favourites of the anecdotes Roger collected on APL Quotations and Anecdotes is one of his own recollections: My career in APL started as a summer student at IPSA Calgary in 1975, where Arthur Whitney was a summer student the year before. On my first day on the job Ian Sharp happened to be visiting, and the whole office went out to lunch with Ian. During lunch I expounded on matters far and wide. Ian watched me for a while, then turned to Lib Gibson, IPSA Calgary branch manager, and asked, “Isn’t Arthur Whitney coming back with us this year?” It was years before I realized that I had been put down. This self-deprecation personifies Roger for me. It’s a quality few possess to the extent that he did, especially when the underlying intelligence is so great. My life is definitely richer for having known him.

Aaron W. Hsu

There are some people whose deeds and greatness follow a singular passion to the exclusion, and sometimes, the neglect of all else and all others. My all too short a time with Roger leads me to believe that he is to be counted not among those singularly driven individuals, but rather that he moved ever closer in his lifetime towards that of a Sage, though I know he himself would deny having remotely come close to attaining such a lofty ideal. I found this quote concerning an ancient concept of the Sage, Sphairos, befitting of Roger, “completely within itself, well-rounded and spherical, so that nothing extraneous can adhere to it, because of its smooth and polished surface.” When I first met Roger, me quite new to array programming, and he quite a bit more experienced, I was struck by his seemingly quiet energy and his measured cadence. I soon discovered Roger was “Iron wrapped in Cotton” and that the strength of his passion and spirit with which he undertook his work and life lacked nothing for its soft exterior.

I count Roger among those true scholars who specialized not in a particular subject, but rather, in the pursuit of excellence and learning. His deep appreciation for not just programming, but the arts, language, beauty, peace, and spirituality impressed me and inspired me. I admire his capacity to steadfastly and directly state his case, with enthusiasm, but never ferocity or malice.

I wish I could have known Roger more personally than time and space permitted, but I cannot imagine anything less than that his integrity and sincerity in his work must have had a similarly great expression in his personal life.

I have little concern for Roger’s own well-being, I am sure he’s doing quite well, but there is no doubt in my mind that we have ourselves been deprived of a great wellspring of wisdom and inspiration and goodness that elevated everything around him just that little bit more.

Andy Shiers


I shall miss Roger very much .. not just his genius, but also the calmness and gravitas which he brought to many a gathering and his child-like delight at what must be admitted to be some pretty awful jokes. Compared with him I am a mere tyro at APL, but we agreed on many a design point, and I will honour the promise I made to him that I would continue his role as an SOB when it comes to making changes which I feel he would not approve of.

Adám Brudzewsky


While Roger and I weren’t always working closely together, we often had discussions about programming language theory and design. I also had the great honour of working on a project we called Total Array Ordering. The bulk of the work was done by Roger, but he still put my name first on the paper. The process itself was very valuable to me. It involved hundreds of emails, back and forth. Roger was passionate, and he was respectful at the same time.

He was also careful: When we were designing the Total Array Ordering, he wanted to make sure that everybody involved understood exactly what’s going on in every detail, and every implication of it, to make sure everything was consistent. Part of his carefulness was to constantly consider what his mentor, Ken, would do. Roger reminded us that he was very familiar with Ken’s papers, having hand-typed a large quantity of Ken’s works. Anybody could have done this, but nobody else did!

According to the above, NASA used to have a division called Space, and of course the head of the division is Director of Space. They then reorganized and created a division called the universe, whose head is … Director of the Universe.

So I’d been wrong for years. Instead of showing my best code to the Galactic Emperor, I should show them to the Director of the Universe. I hope the Galactic Emperor would be amused.

Indeed, Roger spent a lot of effort, including discussions with Guy Steele, who was supervising the “APL Since 1978” paper, to find the very best symbols for missing APL functions, such that when he eventually would present Euler’s identity to the Galactic Emperor, or the Director of the Universe, or whatever it might be, the formula would be as beautiful as possible.

Roger just had his last kick at me: In his collection of APL Puns, there’s an expression claiming, “it’s turtles all the way down”. I pasted it into my APL interpreter, and it put my APL interpreter into a tight spin, attempting to reach the bottom-most turtle. Roger, you got me!

Anna Mah

Roger was my first cousin on my Dad’s side. Brilliant, quiet, and unassuming. Remembered my aunt feeling so proud when he was tied with best math marks at Edmonton Public Schools in his graduating year. His spirit will live on—RIP Roger, from your Cousin Anna.

Bob Therriault

It was a sad day when I heard of Roger’s passing. My condolences to his family and all of those who knew him far better than I.

As a person who only briefly interacted with him, he struck me as a wise and humble man of exceeding intelligence – the qualities that you would always want your heroes to have.

Rest in peace, Roger

Alexander K.W. Hui

I’m Alexander K.W. Hui, the eldest of Roger’s 5 siblings. As you may well know, our fond memories in life do not usually live in a memory stick, but rather in our hearts. As a result, photos of our youthful days are extremely rare. Such is the case of how I remember my Dear Brother Roger, namely of the photo which I share of Roger’s U of A graduation in 1977. My personal tribute is in the form of two photo compositions. One of which would have the Chinese texts: The vertical texts are translated to read as, “To our dearest and most beloved Roger Hui, may you rest well in the Lord’s embrace”. The horizontal line of texts are translated to read as, “Rest in Peace, my Dear Brother Roger. Your life that has been an honor both to God, and to your fellow-man. This is but a brief Adiós. May we meet again, to bask in the eternal Kingdom of God.” In the English texts, you may also notice “To My Beloved Son…..” This was so said, on behalf of our dear mother, who is in her 90s.

Geoff Streeter


At a Dyalog dinner Roger declared himself a “christian atheist”. I reached across the rather large round table and shook his hand.
Sadly we never got to pursue that commonality but I know just how much thinking has to go into being able to put those two words together.

Paul Chapman

Roger was already a legend in the APL community when I first heard of him, and I saw him from time to time from a distance at APL conferences and Minnowbrook meetings. Then in the ’90s I worked should-to-shoulder with him in Ken’s Iverson’s flat in Toronto for a week, porting J to the Acorn Archimedes. Two great privileges in one. I noticed he was in London a few years ago, and even though I thought he would be too busy, I asked him to dinner at my local Italian and he accepted. I always crave in-person conversation with other language designers and implementors, and we got through a lot. (I doubt that I’ll ever have the bravado to contact Alan Kay, who now lives in London.) So I rather selfishly feel that one of the very few of the best of that already rare kind is now lost to me, and I still have so very much to learn. I shall now go and read “APL since 1978”.

“Because it is easy to type.” – Roger Hui

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Roger Kwok Wah Hui

1953 – 2021

Clear, Firm, Intelligent, Decisive, Kind and Gentle.