Goodbye

At the end of May 2019 I am leaving Dyalog, so it seems like a good time to reflect on my time here and what I’ve learned from APL and the APL community.

When I joined Dyalog in 2010 I knew nothing about APL, so there was a really steep learning curve as I got to grips with both the language and its implementation. I was using some of my previous experience with compilers to improve the performance of the implementation, and thinking about ways to compile APL. This is a tough problem, and one that many people have worked on over the years (see for example Timothy Budd’s 1988 book An APL Compiler). My own ideas have shifted as I’ve gained more experience with APL and the way it is used. At first I thought “writing a compiler” was an obvious thing to do; now I think that hybrid compiler/interpreter techniques are much more promising, and Dyalog’s recent experiments with deferred execution and thunks are a good step in that direction.

At the same time, there was a lot of excitement around the APL language itself. Dyalog was working on APL#, a new .NET-based APL dialect (sadly abandoned as Microsoft’s own commitment to .NET waned). And Dyalog APL itself was starting to borrow more language features from the SharpAPL/J branch of the family tree, starting with the Rank operator and continuing over many years. This prompted me to delve more into the history of APL, to try to understand some of the fundamental differences between different implementations, so that we could reconcile those differences in Dyalog APL and provide, as far as possible, the best of both worlds. I think we’ve done pretty well in that, as evidenced by the fact that many APLers are happily using Rank, Key, function trains et al in an APL2-based language, something that seemed unthinkable a decade ago.

One of the most gratifying developments in the time I’ve been working with APL is the rapid growth of new APL implementations, open source projects and grass-roots enthusiasm. In particular, the open source movement has made it much easier for anyone with a good idea about language design to implement it, and share it with the world. We’ve seen a wide variety of new APLs and APL-inspired languages popping up over the years, ranging from full-featured to highly experimental, including but not limited to (in roughly the order I remember hearing about them): ELI, ngn/apl, GNU APL, Ivy, Aprildzaima/APL and APL\iv.

And speaking of new APLs, of course there is Co-dfns, a compiled APL implementation that tries to solve another tough problem: harnessing the power of GPUs and other massively parallel hardware in a way that makes it accessible to the end user. This is something that many people are trying to do, in a wide variety of languages, but as far as I can tell no-one has quite succeeded yet. The state of the art is still that, in order to get good performance, you need quite a lot of mechanical sympathy for the underlying hardware. But Co-dfns has come a long way, and if any language is well-suited to run on parallel array processors then surely it is APL!

This brings me on neatly to my next job: I’ll be working on compilers for GPUs, the parallel computers that render 3D graphics. They are closely related to their “general purpose” cousins the GPGPUs, which are used for pure number crunching, and to so-called tensor processing units (TPUs) that simulate neural networks for use in machine learning and artificial intelligence. “Tensor” here just means an array of arbitrary rank, or as we would say: an array. For programming TPUs there is a Python-based framework called TensorFlow. But, look closely at the APIs for some of the core TensorFlow libraries, and you’ll see operations like reshape, reverse and transpose, which are eerily similar to their APL equivalents. There truly is nothing new under the sun!

With fond regards to all APLers,
Jay.

Welcome Richard Park

Richard Park is the latest addition to the Dyalog team and is based at Dyalog HQ in the UK. Richard has been living in the same house in Bramley his entire life and recently returned to the village after one successful degree in physics at the University of Manchester, and one unsuccessful degree in education at Manchester Metropolitan University.

How Richard and Dyalog came to meet is a story that deserves to be told, albeit a bit embarrassing for poor Richard!

One day, while walking his dog and father, Richard rang the office doorbell to inquire about any software-related opportunities that might be available. He had developed an interest in computers from using them at young age, building circuits for A-level electronics and learning about the physics of computers (as well as computational physics) at University. If only Richard had been able to convey any of that to Jay Foad, who answered the door, instead of standing like a “gormless idiot” (his words) whilst his father jumped in and asked about internships and job opportunities…

Richard went home that evening and browsed the Dyalog website… the Pandora’s box of APL edged ajar and he began to imbibe the symbols. He also sent an amusing email explaining the earlier awkward encounter and clearly showing that he was not a “gormless idiot”. This resulted in a meeting with the CEO and CXO, Gitte and Morten, in October 2018. After that meeting Richard showed enough aptitude and interest, while pair-programming a simplistic physics simulation with Morten, that they decided to keep him.

Given that Richard’s previous experience includes programming an autonomous robot for the QMC team in the 2012 and 2013 Student Robotics competitions and using MATLAB and CERN’s ROOT library to process experimental data and run simulations, he was very surprised that he had never heard of APL before. He sees a potential in APL to develop domain specific programming languages and software packages to help teachers convey concepts in a way which more closely matches the syntax and jargon in which problems are already described.

In his new role at Dyalog, Richard is developing teaching materials and demos to promote APL.

Dan Baronet

Dan Baronet

Dan Baronet

We do not know the details, but Dan’s luck ran out this week. On Tuesday, as he headed South from Nevada into California, en route to Mexico on the first leg of a four month motor cycle adventure to South America, something went wrong … Dan lost control of the bike and collided with a motor home, and many of us are now struggling to comprehend that Dan won’t be back.

Dan made friends everywhere that he went. On our annual Dyalog skiing “retreat” (we frequently did real work on prototypes of new tools, honest!), I was always impressed (while trying to hide my slight embarrassment) by the way Dan always kicked off conversations with hotel staff. Whether the waiters and waitresses were native Italians from the resort town – or migrants as hotel staff frequently are – Dan would typically know enough words in some shared language to get the conversation off to a good start (or he would extend his vocabulary on the spot). This always guaranteed us service with a smile, and excellent advice on which wine to order for dinner.

Dan gave as well as he got: on the slopes, Dan was always the first to stop by anyone who had fallen over and was struggling to get back up. Dan has friends all over the world and always took the time to visit them when he could, to keep the friendships alive. He was also happy to open his own home to travellers, both my kids had little Canadian adventures as guests of Dan and his family in Quebec, and Dyalog team members would also “couch-surf” chez Dan.

At work, Dan also loved extending his vocabulary. He remembered more details of different APL dialects than anyone else that I know, and was an expert in migrating code from one system to another. He also knew the weaknesses of each system, and was a feared visitor to vendor booths at APL conferences. Dan would mischievously sit down to play with a new APL system, try a couple of his favourite edge cases, and usually manage to crash new (and some old) APL interpreters within seconds.

But even when crashing interpreters, Dan was really trying to help the vendor produce a more stable platform. At work, as on the ski slopes, Dan was one of the few people who was always going out of his way to help. When he had spent time learning a new technique, or how to use a new tool, he would go the extra mile to create a utility library, document it, presented it at conferences and APL user meetings. He also did the really hard part – writing an article about it, making frequent contributions to Vector and other publications: http://archive.vector.org.uk/?qry=baronet&submit=search. He also enjoyed teaching APL, as an instructor at I.P.Sharp Associates and in the modern era as the author of numerous tutorials at https://www.youtube.com/user/APLtrainer.

More than 30 years ago, as an APL rookie at I.P.Sharp Associates, I was fortunate to meet, work with, and learn from Dan when he and I both found ourselves at IPSA Copenhagen. In addition to a general interest in tools, I shared Dan’s interest in the migration of code between APL systems, and flying airplanes. Dan actually flew small aircraft (and helicopters!) and I, like so many other friends and colleagues, admired him and got invited along for rides.

A decade and a half later in 2005, as the new CTO of Dyalog, I was keen to add an APL toolsmith to the company. Despite his location in Montreal, Dan was at the top of my list. Dan continued to live in Montreal but was a frequent guest in Bramley, coming over several times a year to spend some weeks to work with the growing “APL Tools Team” – and with the core development team on improving the quality of the interpreter by crashing it in as many ways as he could think of.

When his imagination ran out, he wrote code to generate even more ways to crash the interpreter. Dan has been cursed loudly many times, and will be remembered – if for no other reason than that it will be a long time before we are able to close the last “issues” that he logged in our problem tracking system. The quality of Dyalog APL has increased enormously in the last decade, and we have much to thank Dan for. Dan also “poured the concrete” for the foundations of the source code management tool (SALT) and the User Command framework that we are all starting to take for granted, and contributed to many other pieces of our growing collection of tools.

C-GSXN in Toronto

Dan often flew himself to APL User Meetings

Dan was an adventurer. He skied, snowboarded, snowshoe’d, biked, skated, hiked and flew – and with his great sense of humour and warm personality, he was able to entice many of us to come along with him to share. He photographed and brought his video camera, although he would often manage a 3-week trip to Europe which included a skiing trip, carrying only a small backpack.

Dan had just turned 60, and he had taken four months leave this winter to pursue an old dream to revisit South America with a friend – on motor cycles. They had wisely gone on a trial ride in the late summer, riding from Canada to Las Vegas and parking the bikes there in order to test the equipment and not have to ride two-wheelers in the Canadian winter. As a pilot, Dan understood risks very well – or rather, how not to take unnecessary ones.

“If only he had been a little more cautious”, some will say. Was that trip really necessary? These thoughts are unavoidable – but we have to remember that his decision to ride was natural to the adventurous and mischievous spirit that we all knew and loved.

A message from the CTO

Hello! Further to Morten’s kind words of introduction, I’d like to take this opportunity to introduce myself as the new CTO of Dyalog Ltd.

About me

I’m a newcomer to APL. When I started working for Dyalog in 2010 I had only seen the Game of Life video, an intriguing but baffling glimpse into a world of squiggles. But I soon got the opportunity to learn from some giants of the language, and came to appreciate the power and beauty of the notation. Later I learned that, despite its venerable history, the language is not set in stone; with care and attention we can develop and extend it to increase its power, relevance and performance, without sacrificing its elegance and simplicity.

We — not just Dyalog, but the wider APL community — are guardians of a rare thing: a language born more than 50 years ago that is not just relevant and useful today, but groundbreaking in the way it embodies data parallelism from the ground up in a simple, consistent notation.

Before working at Dyalog I spent 13 years developing compilers, optimisers and debuggers for more mainstream programming languages, including C and Java. This has given me a good insight into how to get the best performance out of modern computer hardware, and I’ve made it my continuing mission to help bring that level of performance to APL!

My rôle

As CTO I’ll be responsible for day-to-day management of the core interpreter development team, and for the overall technical strategy of the company. This strategy must include getting the maximum performance out of current and future hardware, but also:

  • Keeping the quality of the product as high as possible.
  • Embracing new platforms and attracting new users.
  • Improving our development tools, and making it easier to create and deploy new applications.
  • Ensuring that Dyalog APL can interoperate smoothly with modern frameworks and services.
  • Continuing to look at new ways of (carefully!) extending and improving the core APL language.

I’m looking forward to working on this alongside the “new” CXO, Morten. At Dyalog we take a lot of care in the design of new features, and I firmly believe that a lively discussion between CXO (representing the needs of the customer) and CTO (representing the language designers and implementers) will only improve the quality of the designs we come up with.

On the road

In the future I expect to spend a bit more time out and about, showing off Dyalog APL, and talking to all of you about your own needs and expectations of the product. In particular, this year I’ll be at DYNA16 in Princeton in April, and the Dyalog ’16 User Meeting in Glasgow in October. I look forward to seeing, or meeting, all of you soon!