Dan Baronet

Daniel Baronet (far left) at IPSA50 reunion

Daniel Baronet (6 May 1956–1 Nov 2016), also known as APLtrainer, was an APL (and later J) programmer since 1976, working for I.P. Sharp Associates in Melbourne, Toronto, Montreal, and Copenhagen, from 1983 to 1988, and for Dyalog Ltd from 2006 until his death.

Baronet was responsible for Dyalog's Simple APL Library Toolkit (SALT) and its framework for user commands (affectionately known as spice), but also worked on many other APL tools through his company Milinta Inc, specialising in the development of free open-source tools to transfer of APL code between dialects. He was a prolific writer and presented at many events.

The "Dan Baronet special"

Baronet was famous for innovative uses of APL primitives. He's credited with discovering that <source lang=APL inline>b⊥b</syntaxhighlight> or, as he preferred writing it, <source lang=APL inline>⊥⍨b</syntaxhighlight>, counts the number of trailing ones in the Boolean vector <source lang=APL inline>b</syntaxhighlight>:

<source lang=apl inline>⊥</syntaxhighlight> (Decode) performs base conversion. If the left argument is a vector, it performs mixed base conversion.

For a base vector $b=b_{n},\cdots ,b_{0}$ and a digit vector $a=a_{n},\cdots ,a_{0}$, <source lang=apl inline>b ⊥ a</syntaxhighlight> converts $a$ to the mixed base $b$, i.e., it computes $b_{0}\cdots b_{n-1}a_{n}+\cdots +b_{0}b_{1}a_{2}+b_{0}a_{1}+a_{0}$.

Now, in a monadic context, <source lang=apl inline>⍨</syntaxhighlight> (Commute) causes the function to the left to be called with equal left and right arguments.

So <source lang=apl inline>⊥⍨b</syntaxhighlight> is defined as <source lang=apl inline>b⊥b</syntaxhighlight>, which computes $a_{0}\cdots a_{n}+\cdots +a_{0}a_{1}a_{2}+a_{0}a_{1}+a_{0}$, the sum of all cumulative products from the right to the left.

For <source lang=apl inline>k</syntaxhighlight> trailing ones, the <source lang=apl inline>k</syntaxhighlight> rightmost products are <source lang=apl inline>1</syntaxhighlight> and all others are <source lang=apl inline>0</syntaxhighlight>, so their sum is equal to <source lang=apl inline>k</syntaxhighlight>.

Publications

• Articles in the Vector journal
• APLtrainer ― YouTube videos

APL conferences

• APL03: NAVPLANR (NP): flight navigation planning software.

Dyalog user meetings

• Dyalog '06 W05: Introduction to Object Oriented Programming using Dyalog version 11.0 (materials)
• Dyalog '07 05: SALT, Subversion and the Dyalog Code Library (materials)
• Dyalog '07 W01: Introduction to Object Oriented Programming using Dyalog version 11.0
• Dyalog '08 W04: Source Code Management using SALT and Subversion (materials)
• Dyalog '08 W08: Introduction to Object-Oriented Programming (materials)
• Dyalog '09 C02: Introduction to Object-Oriented Programming (materials)
• Dyalog '09 C06: Source Code Management using SALT and SubVersion (part I) (materials)
• Dyalog '09 C09: Source Code Management using SALT and SubVersion (part II)
• Dyalog '10 TU3: User Commands in Dyalog APL
• Dyalog '11 C01: Introduction to Object-Oriented Programming (materials)
• Dyalog '11 C06: Windows Presentation Foundation (materials) (with Michael Hughes)
• Dyalog '11 C07: Productivity Tools for Dyalog Users (materials)
• Dyalog '12 D07: New SALT features and User Commands
• Dyalog '12 C02: User Commands (materials)
• Dyalog '12 C07: Starting a New Application in Dyalog APL (materials) (with Morten Kromberg)
• Dyalog '12 C09: Managing External Data III (materials) (with Gitte Christensen)
• Dyalog '13 D15: User Command Update (slides)
• Dyalog '13 SA03: OO and CC
• Dyalog '13 SP03: User Commands
• Dyalog '14 SA03: Parallel Programming with Futures and Isolates (materials) (with Morten Kromberg)
• Dyalog '14 SP02: The Ins and Outs of Data (SQAPL, XML, JSON, Excel, Syncfusion Data Objects, ZIP files, …) (materials) (with Brian Becker)
• Dyalog '14 TP04: Version 14.0 Language Features in Practice (slides)
• Dyalog '15 D05: User Commands Update (with Adám Brudzewsky)
• Dyalog '15 D10: MiServer UI Controls (slides) (with Adám Brudzewsky)
• Dyalog '16 D04: Tools Group Update (with Brian Becker and Adám Brudzewsky)
• Dyalog '16 TP01: Version 15.0 in Depth