Dyalog ’19 Videos: Week 4

Welcome to week 4 of the Dyalog ’19 recordings! This week, Tommy Johannesen of Jersie Data tells us about an interesting application that he has written in Dyalog APL. In the Copenhagen area, many school children are “fed with APL” in the sense that Tommy’s APL system connects the parents of ten thousand hungry children to about 60 vendors of school lunches. The service currently handles about 100,000 users with a system that runs under IIS and uses Dyalog as an ASP.NET implementation language. Each year 10,000 children leave after 10 years at school and another 10,000 enter grade 0; over the 30 years that Tommy has been in business, he has served more than a quarter of a million users.

Tommy Johannesen of Jersie Data

Tommy Johannesen of Jersie Data ApS

Peak time is Sunday evening, when parents and children log on to order meals for the coming week. Tommy tells the story of how he has been struggling with a memory leak that caused some user requests to fail when loads grew large; obviously not a good thing! Since upgrading to Dyalog version 17.0 he has been chasing this problem together with John Daintree – it was not completely solved at the time Tommy was at Dyalog ’19, but I am happy to be able to report that we believe it finally bit the dust in October!

The other two recordings in week 4 are centred around the topic of source code management. First, Adám Brudzewsky and I introduce the tool called “Link” which is included with version 17.1. Link creates a link (hence the name) between each function (or other “code object”) in an active workspace and a corresponding text file. The namespace structure of the workspace corresponds to the directory structure that the workspace is linked to. Changes made to either side of such a link – to code in the workspace or to files outside it – are immediately reflected on the other side.

Paul Mansour of the Carlisle Group

Paul Mansour demonstrates Git integration with AcreTools

The intention of a tool like Link is to enable the use of source code management systems like SVN or Git to manage source in the form of text files. These source code management systems allow the implementation of many different “workflows”, defined by parameters like how branches are used, how frequently merges are done, and how conflicts are handled. Git allows a lot of freedom, which many small teams (and that includes one-man-bands 😊) don’t need. Immediately following the talk on Link, Paul Mansour took the stage at Dyalog ’19 to talk about tools that he has developed to implement a simple but effective Git workflow, suitable for many APL projects.

Summary of this week’s videos:

Dyalog ’19 Videos: Week 3

Stig Nielsen of SimCorp

Stig Nielsen of SimCorp

In the third week of Dyalog ’19 recordings, Stig Nielsen from SimCorp A/S talks about recent work to turn a very large body of APL code, originally designed to work well on workstations, into a 3-tier solution. This requires turning everything “inside out”, making the application a service that can be called from cloud-based components. Fortunately, the parts of the application that have been implemented in APL have been using a model-driven approach to user interface specification for decades. This makes the task a lot simpler compared to some of the code written in other languages (which needs a complete rewrite). Stig explains both the obvious solution and the one that might actually work.

Brian Becker shows us the HTMLRenderer

Brian Becker shows us the HTMLRenderer

The other two talks that we are releasing this week are also related to producing portable user interfaces. The HTMLRenderer is a component that is integrated with Dyalog APL under Microsoft Windows, GNU Linux and Apple macOS. It allows APL applications to use HTML/JavaScript to produce Desktop applications that behave identically on all these platforms – in much the same way that NodeJS allows. Brian Becker introduces new features of the HTMLRenderer in version 17.1, and a number of tools that allow you to build user interfaces that run not only on the HTMLRenderer, but also as a Web Server.

Josh David demonstrates his Easy GUI

Josh David demonstrates his Easy GUI

Josh David follows up with a talk about “EasyGUI”, a tool that he built as his final year project at Scranton University. EasyGUI is built upon the HTMLRenderer, and allows applications to have a very simple UI for collecting input from the user and for displaying progress bars, simple reports or graphics. It does this without requiring that the user learn any HTML, JavaScript or CSS – it is all generated by a set of very simple functions.

Summary of this week’s videos:

See you next week for the next three recordings from Dyalog ’19.

Dyalog ’19 Videos: Week 2

Welcome to the second week of recordings from Dyalog ’19 in Elsinore! This week we are featuring three presentations about work that is either already available, or will appear in Dyalog version 18.0 in 2020.

APLcart logo

All three talks are by members of the Dyalog development team, but Adám Brudzewsky’s talk on APLcart is labelled U14 because the bulk of the work has been done in his own time. APLcart is a novel way of making it easy to find information about how to do things in APL, as opposed to finding documentation for a particular feature of the language or development environment. Although it is brand new, APLcart is already a very effective tool. I recently had the pleasure of teaching an introductory APL course where I told the students about APLcart on the first day. By the end of the week, every time the students had to solve an exercise, they headed straight for APLcart. Please check it out, try to find things, and let Adám know about anything that you can’t find so he can add it!

Richard Smith talks configuration files

One of our most important goals is to make Dyalog APL as capable – and as similar – as possible on all significant computing platforms, ideally allowing you to develop on any supported platform and deploy the solution to all others. One of the remaining hurdles is configuration of the interpreter, the development environment – and applications. This is currently done very differently from one platform to the next. Richard Smith introduces a project he is working on that aims to provide a single format for configuration files across all platforms. The choice of a file format is not an easy one, and a significant part of this recording consists of comments from the audience – including members of the Dyalog development team – voicing a variety of opinions about this.

Marshall talks tacit techniques

Finally, a delicacy for language geeks: The word tacit means “unspoken”. Tacit programming involves expressions consisting only of functions, operators and constants; the arguments are implied. For example, the expression (+⌿ ÷ ≢) is a function train, which should be read “sum divided by count” – without speaking about what the functions are applied to. The corresponding “explicit” expression would be {(+⌿⍵) ÷ ≢⍵} which mentions the argument twice. In his talk on Tacit Techniques, Marshall explains how tacit programming can be elegant and powerful, and why a set of new operators planned for Dyalog version 18.0 will be particularly useful for tacit programming. His talk includes a neat way of ranking poker hands with the over () operator, which will be available in Dyalog version 18.0.

Summary of this week’s videos:

Join us again next week for another three recordings from Dyalog ’19.

Welcome to the Dyalog ’19 Videos!

It is still true that most APL users live north of the equator, which means that at this time of year the sun is below the horizon more than half the time. It’s the perfect time to snuggle up in a warm place and watch some videos, and we’ll be offering you about three a week from now until just after the Winter Solstice, when we can start looking forward to the Spring.

As usual, we’ll be releasing videos of the vast majority of the presentations that were made at the recent Dyalog ’19 user meeting, which was held in Elsinore, Denmark in September. If you would like to get a feeling for what is coming, take a look at the blogs from the meeting itself, starting with this one.

In accordance with tradition, we’re opening with the three keynote presentations by Dyalog’s CEO Gitte Christensen, CTO Morten Kromberg, and Chief Architect John Daintree.

Gitte welcomes delegates to Dyalog '19

2019 is the first “Year of the Hammer”: after seven years of Norse wyrms and seven years of Viking ships, we were now entering the era of seven hammer-inspired logos. As Gitte explains in her talk, we are celebrating the first year under Thor’s Hammer by making Dyalog APL freely available for non-commercial use – without requiring registration – under Microsoft Windows, Apple macOS and GNU/Linux (including a collection of public Docker images). The intention is to make APL much more easily accessible for experiments – especially in the cloud!

Gitte’s talk also contains sombre tones, remembering that we lost John Scholes in February as well as Harriett Neville, who had registered to attend Dyalog ’19 but passed away most unexpectedly just before the meeting.

After last year’s Technical Road Map, which was almost entirely a live demonstration of using APL with modern development tools like Git, VS Code and Docker, I decided to play it safe this year and do no demos at all in my keynote. Instead, I concentrated on explaining some of our thoughts about making Dyalog APL easier to discover, learn and integrate into modern frameworks and development processes – and making applications written in APL easier to deploy and maintain. As a result, despite the world premiere of our new Webinar Jingle, composed by Stefano Lanzavecchia (short and long versions are available), I probably shocked the audience by leaving three minutes at the end for questions!

 

The title of John’s talk was “Cor(e) Blimey!”. The Cor(e) is of course a reference to Microsoft’s “.NET Core” but if English is not your first language, the title of John’s talk may need a little explanation. “Cor blimey” is an exclamation of surprise, a euphemism derived from “God Blind Me”. In this talk, John explains how Dyalog is poised to provide a bridge to Microsoft’s new portable, open source version of .NET. Scheduled for release with Dyalog version 18.0 next year, this will provide APL users with access to a vast collection of libraries under Linux and macOS, in addition to Windows.

Summary of this week’s videos:

I hope you enjoy these presentations. Join us again next week for another three recordings from Dyalog ’19!

Dyalog ’18 Videos, Final Week

Welcome to the eighth – and final – week of recordings from the Dyalog User Meeting in Belfast! I’d like to take this opportunity to thank all the speakers who helped make Dyalog ’18 another valuable experience! Fittingly, we’re wrapping up with a larger, and even more varied collection than usual: two talks by members of the Dyalog team, two by users of Dyalog APL, and one from the British APL Association – five in total!

1. There are big changes afoot at the British APL Association and Paul Grosvenor, the chairman of the BAA, took to the stage in Belfast to tell us about them. Most importantly, the Vector magazine is going online after 25 years as a printed publication – and the removal of printing costs means that membership is now free! An annual conference in April/May is being planned. There has never been a better time to join the BAA, and you don’t need to live in the UK to do so! In addition to watching Paul’s talk, you can read about many of the changes here and on the new vector website (coming soon!).

2. Arianna Francia from SimCorp Italiana works in one of the largest APL development teams in the world. IFRS 9 is an International Financial Reporting Standard (IFRS) promulgated by the International Accounting Standards Board (IASB). Fortunately, although Arianna’s talk is titled “The IFRS 9 Project”, she completely avoids the subject of IFRS, and instead offers valuable insights into how a rapidly growing team, faced with an extraordinarily complex project, adapted and adopted a combination of agile practices and ideas from Ed Catmull’s book Creativity, Inc, which is about his experience managing Pixar.

3. For many Dyalog users, the least attractive aspect of Dyalog’s MiServer as a tool for cross-platform user interfaces is that it comes with a completely new set of controls or “widgets”, which essentially means you will need to rewrite your ⎕WC-based user interface. If you are facing this problem, Chris and Michael Hughes have very good news for you: in their talk “⎕WC on the Web”, they demonstrate a new tool that emulates ⎕WC, allowing you to create your UI in a web browser or the HTMLRenderer component included with recent versions of Dyalog APL.

4. Nested arrays make it easy – sometimes, too easy – to represent tables as 2-dimensional arrays. However, if each column of a matrix has the same data type, there are very significant savings to be had in both space and time if you “invert” such tables and represent them as a list of vectors, each containing the values for one column. In his talk on “Inverted Tables”, Roger Hui evolves a set of short, elegant and efficient functions for common operations on inverted tables.

5. It appears that the APL community came very close to losing John Scholes after he read the September 1989 edition of British Computer Journal special edition on Lazy Functional Languages and was struck by the beauty of functional programming. Fortunately, John decided to work on functional extensions to APL, and came up with dfns. This new notation was added to APL in 1996, only six years after Haskell 1.0 appeared. In his talk entitled “dfns, past present and future”, John revisits the early days and muses about things that could have been done differently, but quickly moves on to talk about ideas for future extensions to dfns, like guarded guards, where clauses, and optional type specifications.

I hope that you enjoy watching your choice of recordings as I have enjoyed revisiting them in order to write about them. As you may have noticed, we have taken a break from webinars while we have been rolling the Dyalog’18 recordings out. Now that we’re done, remember to set time aside at 16:00 (U.K. time) on the 3rd Thursday of each Month to follow the webinar series. The next webinar will be on Thursday February 21st: a presentation by our CTO Jay Foad, on his adventures as a participant in the Advent of Code programming competition, which was held in December.

Summary of this week’s videos:

Dyalog ’18 Videos, Week 2

Each week until early January, we will be releasing a selection of recordings of presentations from Dyalog’18, which was held in Belfast at the end of October 2018. Last week we kicked off with the opening keynote talks and the prize ceremony and acceptance speech by the winner of our annual problem-solving competition.

Just under half of the presentations at Dyalog User Meetings are by users who have volunteered – or sometimes been commandeered – to share stories about how they have used APL for fun or profit. These user stories provide significant motivation to the Dyalog team for future direction.

Aaron Hsu’s talk on “High Performance Tree Wrangling, the APL Way” is a pearl. Back in 2015 I gave a talk at Google on APL. One of the Google engineers asked about working with trees in APL and I was unable to give him a useful answer. Aaron is working on a compiler for APL, and trees that represent the code that is being compiled are his most important type of data structure.

In this talk Aaron demonstrates that APL is an elegant – and highly efficient – notation for working with trees, if you just pick the right representation!


Most of the talks at Dyalog User Meetings are fairly technical. The subject at the core of Ilaria Piccirilli’s talk – the fair pricing of financial instruments and subsequent evaluation of portfolios – is no exception. Mercifully, Ilaria spares us the details of the calculations – as she dryly notes, there is no “Fair Pricing for Dummies”. Instead, she offers humorous insights into the way her team used APL to deal with the explosion of computations required by regular additions to legislation requiring health checks – and the day that negative interest pulled the rug out from under most standard pricing calculations.

The other, slightly larger half of the talks at Dyalog Users meetings are by members of the Dyalog Team, talking about work that has recently been done on our products or presenting designs for future enhancements.


Adám Brudzewsky’s talk, titled Array Notation Mk III, is about a potential future extension to the APL language, which will make it possible to easily and clearly describe arrays of high rank, or with deeply nested structure, without using APL primitives to “construct” them, as is common practice today. In addition to making application code easier to read and write, a literal notation for data structures will make it easy to use text files to describe data structures which are essentially part of the source code of an application, and should be managed by a source code management system. As the name suggests, this work has been ongoing for some time, with the initial inspiration coming from a user presentation by Phil Last, back at Dyalog ’15 in Sicily. Watch the presentation and give us feedback on whether you think this idea is now sufficiently baked to become part of Dyalog APL, or we’ll need a “Mk IV” talk next year!


With the growth in usage of Dyalog APL under macOS and Linux – especially in server or cloud environments – the Dyalog Remote Integrated Development Environment is becoming a “mainstream” tool, rather than the curiosity that it was during the first few years of development. Our partners at Optima Systems are developing RIDE on Dyalog’s behalf, and Gilgamesh Athoraya is now the lead developer. In his talk on “RIDE 4.1 and Next Generation Integrations”, Gil talks first about significant new features and performance improvements to RIDE in 4.1 – and then continues to talk about how components of the RIDE technology may be re-purposed to provide APL add-ins for popular development frameworks like the new Microsoft VS Code.

Summary of this week’s videos: