APL Cultivation

APL Cultivation was a series of 90-minute live chat lessons given by Adám Brudzewsky in the APL Orchard chat room in the period 2017–2020. Over the course of 2021–2022, Stefan Kruger edited the content into a book called APL Cultivations.

The first season consisted of 29 weekly sessions running from 18 October 2017 until 16 May 2018, covering most aspects of basic APL programming. Initially, the lessons were not organised, but were given completely impromptu. However, between lessons 2 and 3, Erik Konstantopoulos bookmarked the first two lessons using Stack Exchange's chat conversation bookmarking feature, and thus established the lessons as a numbered series. The name was first used for lesson 15 at the end of January 2018, but was since applied retroactively to all such lessons.

The series continued on 28 November 2019, with more in-depth lessons every two-three weeks. This was sparked by interest among participants of a presentation by Morten Kromberg and Aaron Hsu called Pragmatic Array Oriented Functional Programming, held during Jio talks 2019, after which a series of "APL Hacknights" were to be held in the APL Orchard. However, the audience of the first such eventtypos turned out mostly to be people who had not been at the Jio talk, and it was decided to fold this new series into a continuation of the previous one. This series ran for 20 sessions until 25 August, 2020.

Lessons

First season

Lesson	Title	Date
1	Introduction to Arrays in APL	Oct 18, 2017
2	Diving Into Functions in APL	Oct 25, 2017
3	Some APL Operators: / ⌿ \ ⍀ ¨ ⍣ ⍨	Nov 1, 2017
4	More APL operators: ∘ @ ⌶	Nov 8, 2017
5	Even more APL operators: ⌺ ⌸	Nov 15, 2017
6	APL functions: +-×÷*⍟⌹○!? !⌈⌊⊥⊤⊣⊢ =≠≤<>≥≡≢ ∨∧⍲⍱ ↑↓	Nov 22, 2017
7	APL functions: ⊂⊃⊆⌷	Nov 29, 2017
8	APL functions: ⍋⍒ ⍳	Dec 6, 2017
9	APL functions: ⍸∊⍷∪∩~ /\⌿⍀ ,⍪	Dec 13, 2017
10	APL functions ⍴⌽⊖⍉ ⍎⍕	Dec 20, 2017
11	System Functions: behaviour, session	Jan 3, 2018
12	Constants, tools & external utils	Jan 10, 2018
13	Code management, I/O, dates, Unicode files, errors	Jan 17, 2018
14	Stack & workspace info, misc	Jan 24, 2018
15	Control structures	Jan 31, 2018
16	APL objects: namespaces	Feb 6, 2018
17	APL objects: classes	Feb 14, 2018
18	Class constructors & destructors	Feb 21, 2018
19	APL objects: class properties	Feb 27, 2018
20	APL objects: many-in-one properties, inheritance	Mar 7, 2018
21	APL objects: overriding methods, keyed/numbered properties	Mar 14, 2018
22	Programming techniques and style	Mar 21, 2018
23	Transcribing to and reading trains	Mar 28, 2018
24	⎕R and ⎕S	Apr 3, 2018
25	Understanding function application	Apr 11, 2018
26	Concurrent APL threads	Apr 18, 2018
27	Lookup without replacement	Apr 25, 2018
28	User commands	May 9, 2018
29	More user commands	May 16, 2018

Second season

Lesson	Title	Date
30	Counting words faster	Nov 28, 2019
31	Tradfns	Dec 19, 2019
32	Basic use of ⍤	Jan 2, 2020
33	Advanced use of ⍤	Jan 16, 2020
34	f⍣k in depth	Jan 30, 2020
35	f⍣g in depth	Feb 13, 2020
36	The variant option operator: ⍠ ⎕OPT	Feb 27, 2020
37	⊥ in depth	Mar 12, 2020
38	⊤ in depth	Mar 26, 2020
39	Array programming techniques	Apr 7, 2020
40	Condition-controlled loops	Apr 21, 2020
41	⌹ in depth	May 5, 2020
42	Array coding style in depth	May 12, 2020
43	Complex numbers in depth	Jun 2, 2020
44	Simple plotting (with Nicolas Delcros)	Jun 16, 2020
45	Simple plotting continued (with Nicolas Delcros)	Jun 30, 2020
46	Unique mask ≠ and constant ⍨	Jul 14, 2020
47	Atop ⍤ and Over ⍥	Jul 28, 2020
48	⎕C ⎕DT 1200⌶	Aug 11, 2020
49	Extensions in 18.0: ⊂ ⍸⍣¯1 ⎕JSON	Aug 25, 2020

External links

• Statistics for all lessons