Conway's Game Of Life in APL

> My point was that general programming usually looks more like writing the sorting algorithm than simply calling it. Thus, I would be more interested in seeing real examples of how the properties of J allow you to write algorithms more concisely or otherwise better. Ah - I see. Here[1] is quicksort in j. John scholes's videos are excellent and very illustrative, though they deal with apl rather than j; conway's game of life[2] and sudoku[3]. > The article showed how J solves some mathematical problems with built in functions or their built-in modifiers. But in general programming, you won't find a function that does exactly what you wanted, maybe with a little adverb. You'll usually have to write that function yourself, to describe how it works in terms of some of those pre-existing functions. Right. This is true, but you generally stay much closer to the builtins in j than you do in other language. > Note that your second example could be expressed as something like > x.OrderBy(y => y[1]) > In C#, assuming x is int[N][M]. I understand that J's version can work with many other shapes of X, but that is hard to appreciate without seeing example of how that comes in handy when writing some other (hopefully well known) algorithm. Right; you mentioned sort predicates, so I was giving an example of a way in which you could sort according to another relation. My point is: being able to change the layout of your data so easily can obviate sort predicates. (Though I do think a sort a

in “J Notation as a Tool of Thought” · View on HN

APL (and I assume J) uses a large range of special graphic symbols as part of its syntax, which can be difficult to internalize for folks coming from other languages. It can be easily construed as mysterious or magical lettering (arcane rune). My favorite video to illustrate this is Conway's Game of Life written in APL: ▶ this video

in “Klong: a Simple Array Language” · View on HN

I think the key to understanding APL is realizing that it’s not built for Programmers; it’s built for Mathematicians. Here’s a fine half-hour introduction to APL in action: [link] 1:00-2:00 is the motivation for APL—or any DSL—in a nutshell. (“conversational computing”, “users who are [not] professional programmers”) Or, if you’re happy to sit back and see math magic happen: ▶ this video For all its mechanical advances over the last 40 years, it’s shocking how far our technology has regressed philosophically.

in “A+, the Programming Language of Morgan Stanley” · View on HN

I always liked this example: Conway's Game of Life in One Line of APL ▶ this video It's esoteric as one-liners tend to be, but I think it's a fascinating glimpse.

in “Alan Kay on “What Made APL Programming So Revolutionary?”” · View on HN

For an infinitely more relaxing experience of life in APL, may I recommend: ▶ this video I've watched it many times but I still expect him to mention happy little trees :)

in “Conway's Game of Life in One Line of APL (2007)” · View on HN

Would you prefer something like this numpy then? def life(x): y = np.array([np.roll(x, -1), np.roll(x, 0),np.roll(x, 1)]) y = np.array([np.roll(y, -1, 1), np.roll(y, 0, 1),np.roll(y, 1, 1)]) z = y.sum(1).sum(0) a = np.array([3 == z, 4==z]) c = np.logical_and(np.array([np.ones(x.shape), x]), a) return np.logical_or(c[0], c[1]) Video of Scholes building up the life APL expression can be seen here: ▶ this video

in “Why "Structure and Interpretation of Computer Programs" matters (2011)” · View on HN

There is also the J language [1], which I understand to be a GPL reimplementation of APL. Since they went with pure ASCII, you presumably have to hold down modifier keys less. I never used either language, so can’t comment on how useful they are. But I’ve always been fascinated with APL as an idea, especially after watching this [2] person implement Game of Life as a compact one-liner in APL! (With that compact code, maybe you press modifiers less overall than when writing more traditional/verbose languages?) [1]: [link] [2]: ▶ this video

in “Dyalog APL Keyboard Layouts” · View on HN

Contrarian answer: Conway's Game of Life in Dyalog APL ▶ this video It feels like the logical end state of "clever" code, for better or for worse. Or, alternatively, what happens when a standard library is gigantic but each keyword is 1-2 characters.

in “Ask HN: What's the best source code you've read?” · View on HN

> that you consider a failure It isn't a failure. It simply isn't optimal. Just my opinion, of course. Which means I could be very wrong. > "the pointer returned by this function must be freed by the caller" or "the pointer returned by this function must NEVER be freed by the caller." Those two are examples of bad programming. Both constraints are almost guaranteed to create, at a minimum, an unmanageable mess and, at worst, very dangerous software (think embedded controller for a robot or a rocket). While I have not looked, I would be very surprised if something like that existed in the Linux codebase, which is C. > that doesn't mean C has to be the absolute last systems language ever in the history of computing. I don't think I have suggested this at all in this conversation. My position is very simple: Don't blame the language for bad programming. This is rarely the problem. The fact that someone can cause a mess using pointers does not mean pointers are the problem. They simply don't know what they are doing. The Linux codebase uses pointers everywhere, right? Is it a mess? No. Maybe that's because they are using the language correctly. I am also not saying that all work in evolving programming languages should stop because C is perfect. Not the case I have made at all. What I will say is that --again, my opinion-- quite a few of the modern paradigms are complete nonsense in support of lazy programmers. The question to ask might be something like: Would you have been able

in “Volvo is using Rust for its in-vehicle software” · View on HN

I’m adding SNOBOL to my list of modernist languages. “Everything is pattern-matching” fits the modernist ethos. On the other hand, what about APL? Although the syntax looks just as much like line noise as Perl’s syntax, it is actually a very elegant language. Is APL also a modernist language? ▶ this video

in “Perl, the first postmodern computer language (1999)” · View on HN

life←{ ⍝ John Conway's "Game of Life". ↑1 ⍵∨.^3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ ⍝ Expression for next generation. } ▶ this video

in “GNU APL 1.0” · View on HN

I've always found APL really intriguing. A professor of mine told me about how one of his students used to be able to solve ACM competition problems incredibly fast by simply not having to type very much. There are some insane videos on youtube of people solving problems in APL [1]. But, you know - it's write once, read.. never again. [1] ▶ this video

in “Why APL Is Still Cool” · View on HN

"Notation as a Tool of Thought" by Kenneth E. Iverson in his 1979 ACM Turing Award Lecture. [link] "Language as an Intellectual Tool: From Hieroglyphics to APL" by Donald B. McIntyre in IBM Systems Journal Vol.30, No.4 1991, p.554-581. [link] Conway's Game of Life in one line of APL [link] Conway's Game Of Life in APL ▶ this video

in “Programming languages that make you think differently” · View on HN

Heh. The traditional snippet associated with that argument is the Game of Life in APL. ▶ this video And yes, this is specifically why I opted to redefine "power" in my post; the standard definition leaves out some points that I've found to be essential.

in “Omega programming language” · View on HN