The APL Orchard

5:01 AM

@rak1507 While a neat exercise, be aware that that isn't a good practice. It won't work with a non-scalar function, and the solution is bad. Look at the (long) conversation that follows this message.

rak1507

10:00 AM

Alright thanks

They seem to be discussing F¨ though, which is not what I was doing

{(⍺⍺¨ ⍵) / ⍵} is what they were arguing against, {(⍺⍺ ⍵) / ⍵} is what I had

Adám

@rak1507 Sure, but then what happens if you use a non-scalar decision function?

rak1507

Why would I do that though

rak1507

10:17 AM

For context, the problem was to try and find a 6 digit square number so the last 3 digits were 1 more than the first 3 (like 183184)

my solution was digit ← 1=1000∘|-⌊÷∘1000 ⋄ square ← 0=1|*∘0.5 ⋄ filter ← {(⍺⍺ ⍵)/⍵} ⋄ (digit∧square) filter 100000↓⍳1000000

Adám

10:28 AM

@rak1507 Sure, but someone might write a naive filter←{((6=≢)∧(⍎3∘↓)=1+∘⍎3∘↑)⍕⍵}¨

dzaima

@Adám they could just as easily do that with using plain / though

Adám

@dzaima Yes, but then you see the ¨

dzaima

@Adám i see an ¨ in your filter definition too :|

@Adám (fwiw i think i do filter-by-function enough that it'd be worth some usability; ⌿ being usable in a train of (f⌿⊢) probably competes with my usage of ⍬2⍴ (and, respectively, annoyance of unusability in Dyalog); BQNs f⊸/ is very nice)

Adám

@dzaima Yes, but (and I was using the wrong function name) that was to indicate that for an un-¨d function to work, the utility filter operator has to have a built-in ¨.

@dzaima If we add ⍛ then f⍛⌿⍨ isn't so bad.

dzaima

@Adám (i assumed you were) if there were a filter built-in, it should not have the implicit ¨. And when that's the case (assuming a single symbol for filter), there should be no case the ¨ is less noticable with it than with the corresponding /

Adám

10:34 AM

OK, that's acceptable.

Maybe I'd say filter (let's call it ⍁ for now) should be defined as {⍺←⊢ ⋄ ⍵⌿⍨⍺⍺ ⍺} so X f⍁ Y is filter Y by X and f⍁ Y is filter Y by Y.

Although, then it'd make sense to allow a constant instead of f, and then we have compress (as an operator ― that's what APL2 does) again :-)

dzaima

@Adám well, if that still handled a function operand as filter, that'd be just fine :p

rak1507

Having a maximum of two arguments seems quite limiting, for example, if I wanted to implement modular exponentiation, that would need 3 arguments. How should I go about doing this?

Adám

@rak1507 Normally, you'd take a vector of arguments. Alternatively, you can use an array operand.

Btw, tradfns can auto-enforce that their right argument is a vector of a specific number of arguments.

rak1507

Alright cool

Adám

10:52 AM

@rak1507 E.g.:

      ∇ r←PowMod(x y z)
        r←x|y*z
      ∇
      PowMod 3 1 4
1
      PowMod 3 1 4 0
LENGTH ERROR: Right argument must be a vector of correct length
      PowMod 3 1 4 0
      ∧

rak1507

11:06 AM

Ah nice

{(⊢×2*≢-⍳∘≢)2(⊥⍣¯1)⍵}

Is there a better way to get the binary components?

I feel like I'm overlooking something

Also can you increase the precision? Floating points are ruining my life

powmod←{(b e m)←⍵ ⋄ m|×/m|b*0~⍨(⊢×2*≢-⍳∘≢)2(⊥⍣¯1)e} well this sorta works

dzaima

@rak1507 you can do ⎕FR←1287 to double the precision, but that's still floating point, just bigger

(you can use 123x in NARS2000 (but it doesn't have ⊥⍣¯1) or 123L in dzaima/APL:)

dzaima.github.io/paste/…

Adám

11:26 AM

@rak1507 Btw, APLcart has powmod.

rak1507

I saw, but it was a bit complicated and I thought it would be good practice to make my own anyway

Adám

Right, I figured.

RGS

12:18 PM

@rak1507 I'm not saying it is the best PowerMod ever, but you can take a look at what I wrote for the competition:

PowerMod ← {
    ⍝ For integers (a b)←⍵ computes a*b mod ⍺.
    (base exp) ← ⍵
    0=exp: 1
    m ← ⍺
    bin ← ⌽2∘⊥⍣¯1⊢ exp
    l ← ≢bin
    powers ← l↑ {l≤≢⍵:⍵ ⋄ ⍵,m|2*⍨¯1↑⍵}⍣≡ base ⍝ extend the vector of powers to include all (base*2*k) needed.
    {m|⍺×⍵}/ bin/powers
}

RGS

12:40 PM

I am writing some code that is heavily matrix oriented

and involves plenty of linear algebra

and I need to keep track of plenty of matrices and column vectors to do maths with them... and I wanted to store them in efficient ways, but they all have varying shapes, so I don't really know what is the best way to handle them...

rak1507

1:06 PM

Oh, this was a competition problem? Cool

RGS

@rak1507 under disguise, but yeah, pretty much

rak1507

Phase 1 or 2? and which year?

RGS

@rak1507 this year's phase 2 had a problem on combinatorics

if you stripped it of unnecessary prose, it reduced to powermod

it is originally from rosalind.info

The "sset" problem, with the same name in the website above and the coding competition

rak1507

1:25 PM

Oh cool, thanks, I'll have a look

Razetime

2:27 PM

the gamma function of n+1 is !

the gamma function of n is (!-∘1)n

26

Q: Vandermonde Determinant

Given a vector of n values (x1,x2,x3,...,xn) return the determinant of the corresponding Vandermonde matrix \$V(x_1, x_2, \ldots, x_n)\$. This determinant can be written as: \$\det V(x_1, x_2, \ldots x_n) = \prod_\limits{1 \leqslant i < j \leqslant n} (x_j - x_i)\$ Details Your program/function h...

how does the gamma function defined here work in APL?

RGS

@Razetime I don't understand. In the question you linked they don't talk about the gamma function

Razetime

the pi function is a version of the gamma function right

This is what I got from a google: en.wikipedia.org/wiki/Gamma_function#Pi_function

Adám

Announcement: BAA Webinar Using SVG from Dyalog APL for animated visualisation begins in 25 mins. See details here.

RGS

@Razetime that "pi function" is actually a product

the set of indices under the pi gives it away

it is to the multiplication what Sigma is to the sum

Razetime

ohhhhh

product of each

@Adám hm, the link doesn't seem to open here.

Adám

2:37 PM

@Razetime It should go to britishaplassociation.org/webinar-schedule-2020/

Razetime

This site can’t be reached
britishaplassociation.org’s server IP address could not be found.

thats what im getting.

it's going to the right link

Adám

OK, the zoom link is zoom.us/j/858532665

RGS

@Razetime works for me :/

Adám

@Razetime isitdownrightnow.com/britishaplassociation.org.html

RGS

@Razetime also this is where @Adám complains about traditional mathematical notation :P

Razetime

2:39 PM

haha nice

@Adám ok another problem

this ite aint coming up either

Adám

Have you tried turning it off and on again?

dzaima

@Razetime something's definitely getting blocked on your end (but you are somehow here)

Razetime

India blocks porn sites and the like

but i don't know why they'd do that with the british apl association

Adám

Well, there is something we call "APL pornography"…

Razetime

Uhhhhhhhhhhhhhhhhhhhhhh

side note: it opened now

Ray's ant orld looks really cool

Adám

2:52 PM

We should have an APL Wiki article on pornography.

Razetime

I'm willing to help write that

but what does it even mean

how does it work?!

Adám

It means completely unreadable APL code.

Razetime

Outsiders have a lot of acess to it then

Adám

acess?

Razetime

access

Adám

2:57 PM

@Razetime E.g. in the classic “APL – an Interactive Approach” by Gilman and Rose, the authors call r←(+/x×y)÷((+/(x←x-(+/x)÷⍴x)*2)×+/(y←y-(+/y)÷⍴y)*2)×.5 “almost pornographic”.

Razetime

why not just call it obfuscated APL?

Adám

Dunno, it has just become the normal lingo among APLers. Similarly, we traditionally call the dual function/operator nature of / "schizophrenia" instead of "hybrid".

dzaima

@Razetime that's no fun

Razetime

Ah I see

pornography it is then

rak1507

Nearly missed the webinar, glad I just was able to join

Adám

3:07 PM

@Razetime :-D I'm beginning a new article on APL Wiki. MediaWiki shows the heading: "Creating Pornography"

Razetime

how nice

Never seen any apl written like this

tbf I've never bothered to see any apl programs outside of code golf

TessellatingHeckler

I suspect a lot of people who reject APL for its "unreadable symbols" don't even know it has block structures and multiline functions, and only ever see "r←(+/x×y)÷((+/(x←x-(+/x)÷⍴x)*2)×+/(y←y-(+/y)÷⍴y)*2)×.5" because that's all that's put on the internet

rak1507

How can I take an array like 1 2 3 4 and return 2-1 4-3

not quite n wise reduce

Adám

@rak1507 -⍨/⍤⊢⌺(⍪2 2)

rak1507

3:26 PM

thanks

Razetime

So I tried out the vandermonde thing

{w←⍵ ⋄ ∊∘.-⍨⍉↑{w*⍵}¨⍳⍴⍵}

is this a correct method of getting the matrix?

matt

@Adám why don't i see it when i search for e.g. "creating"?

rak1507

{×/-∊(⍳≢⍵)↓¨↓∘.-⍨⍵} computes the determinant @Razetime

Razetime

Gotcha

rak1507

can probably be golfed more

Razetime

3:36 PM

but I'm tryna get the other formula instead of determinant

thats why theres inner product with subtraction

Adám

@matt 1) I've not saved it yet, 2) The page is called "Pornography" ― MediaWiki adds "Creating".

rak1507

the question asks for the determinant though

matt

@Adám 1) ah ok 2) interesting

Razetime

brb gonna tell my friends I'm making APL porn

matt

@razetime yesss

Razetime

3:39 PM

@rak1507 which is equal to the product of the differences

rak1507

Yeah, which is what I've done

matt

also @Adám might i suggest changing it to "pomography" with an M just to confuse people

Razetime

@rak1507 wow how does that work

rak1507

outer product differences, and then drop the first 1, 2, 3... to get the unique pairs

then ∊ and ×/

TessellatingHeckler

cmc: scrape the APL orchard chat history for every time Adám has said "<primitive> is defined as <code>" and pull them all into a reference page >_>

Razetime

3:43 PM

I thought the poers were needed for geometric prograssion

guess I was wrong

Adám

@matt Ready.

rak1507

as soon as I saw the jelly answer I thought of outer product difference

Razetime

Anyway, you can submit that

rak1507

I have, but I bet it can be golfed more

doesn't work on TIO for some reason

matt

@Adám sadly my goguardian system wont let me see the page >:(

rak1507

3:46 PM

maybe I'm using some dyalog 18 only feature that I'm unaware of

matt

because of the p**********

Adám

Oh, maybe I should rename the page. Any suggestions?

matt

@Adám change the RN to M

Razetime

@rak1507 seems fine to me

rak1507

Ah cool

TessellatingHeckler

3:48 PM

@matt a clbuttic problem with poorly designed censorship software.

Razetime

maybe Adám knows a way to shorten it, looks pretty condensed so far

Adám

4:42 PM

@matt Can you access aplwiki.com/wiki/Readability?

rak1507

not matt but I can

Adám

@all Feel free to add an "ungolfed" version of the first example.

Marshall

@Adám One-liner is still redlinked in two places. Should be a different page from Readability, I think.

Adám

@Marshall Maybe it can be an entry on that page?

Marshall

@Adám I don't think readability is the only interesting aspect of the APL one-liner phenomenon.

Adám

4:58 PM

Good point.

rak1507

Was looking back through the stars and found this dyalog.com/2017-code-golf-challenge.htm, has anyone thought of doing something this again?

Adám

@rak1507 Do you have any ideas?

I thought of "the least amount of primitives to transform one given array into another given array".

rak1507

That sounds good, or going with the previous one's style, 'least unique primitives to do insert given task here'

dzaima

@Adám primitives as in distinct primitives or tokens?

rak1507

could even do a scoring thing like number of primitives used × code length

lowest score wins

dzaima

5:02 PM

@rak1507 that'd make more sense, otherwise the max score is 7

rak1507

can everything be done in 7 characters?

Adám

@dzaima Probably primitives.

dzaima

@rak1507 yep (and, more recently, golfed)

Adám

@dzaima Oh, no, I didn't mean unique.

rak1507

Jeez @dzaima that's mad

I was thinking of some sort of ⍎ thing

⍎ with ⎕UCS and ⍴⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬⍬ maybe

dzaima

5:05 PM

@rak1507 that gets you to 8

@Adám so built-in function/operator count?

Adám

@dzaima Yes, with a restriction that you can't make assignments.

dzaima

@Adám (and ⍎ obviously)

Adám

@dzaima Right, or simply prohibit character arrays (except as intermediary values).

dzaima

still has a max score by writing some interpreter taking in a number array as a constant, but that'd prooooobably not be an actual problem

matt

@Adám yes

also how does mediawiki know how to syntax highlight apl?! that is amazing

dzaima

5:09 PM

@dzaima (fwiw i think distinct×length is a pretty interesting idea, if not a bit too hard and giving too much advantage to brute-forcing)

rak1507

is it just me or is dyalog.com/uploads/files/2017yeargame.txt corrupted or something?

dzaima

@rak1507 it has a wrong encoding. Downloading and viewing locally works fine

rak1507

so it does, thank you

Adám

You may be able to tell your browser it is Unicode. In Firefox, do Alt,v,c,u

dzaima

(heh, ⎕ is misinterpreted there as • (sshhh ignore that Ž before it) - BQNs equivalent of ⎕)

jimfan

5:37 PM

Okay I showed APL to two of my co-workers today. Initially I asked if they have been doing code golf, then showed them the classic average function in APL (+/÷⍴) and challenged them to do it in shorter code

They haven't heard of APL (which was expected) but when they see (+/÷⍴) I was asked what programming language it is

rak1507

use ≢ instead of ⍴

jimfan

@rak1507 Oh yea I should

rak1507

That's cool that you showed APL to your co workers

matt

@jimfan "apl, i just said that"

rak1507

what did they think

matt

5:40 PM

also... are the APLs here red or green?

jimfan

@matt Red, green?

matt

?

jimfan

@matt How can APL be red or green?

matt

it is a pun. "apl" --> "apple"

jimfan

@rak1507 They weren't particularly interested by APL, so I teased them further with the classic V~V∘.×V←1↓⍳20

Via an email though, gonna chat with them again on Monday

rak1507

5:44 PM

why not ∘.×⍨

jimfan

@matt ;-)

rak1507

the more funny symbols the better

matt

@rak1507 yes

jimfan

@rak1507 And I just found that ((+/∘∊)÷(≢∘∊)) can average arrays of arbitrary size / nesting!

rak1507

(⊢~∘.×⍨)1↓⍳20

jimfan

5:45 PM

Regardless of their shape, depth

@rak1507 By the way, the name "A Programming Language" seems to be interesting to them

matt

@rak1507 we should really invent code anti-golf where you have to use a super long implementation

rak1507

Why not (+⌿÷≢)∘∊?

jimfan

@rak1507 Even better, golfer's spirit

Adám

@jimfan Traditionally both red (scroll way down) and green, but lately, Dyalog has added orange.

RGS

@rak1507 nice

rak1507

5:47 PM

@matt code bowling?

Marshall

@dzaima Bug (maybe regression?) in dzaima/BQN Select:

   0‿¯1 ⊏ "abcde"
ae
   0‿¯1 ⊏ ↕5
ImplementationError: java.lang.ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 5
0‿¯1 ⊏ ↕5
     ^

Adám

@jimfan (+/÷≢)∊ is enough.

jimfan

@Adám I should have pointed them to this

rak1507

ah yeah forgot you can just stick stuff next to each other

jimfan

@Adám Working like a charm

matt

5:50 PM

@rak1507 YES exactly. lets think of an example challenge right quick just to see

rak1507

longest expression to generate the number 1

Adám

But what's the upper limit? You can always just spam ⊢s

rak1507

without using 1 obviously

needs to be not trivially reduce-able

Adám

@rak1507 ≢≢≢≢≢≢≢…≢≢≢≢≢≡⍬

@rak1507 Oh. I think there's such a challenge here somewhere.

rak1507

What about to use all APL symbols in some way

or lots of them

Adám

5:54 PM

@rak1507 Like in the style of the traditional idiom for the meaning of life?

rak1507

Don't think I've seen that one

Adám

@rak1507 aplcart.info?q=traditional meaning of life

rak1507

Wow that's amazing

Yeah exactly like that

Adám

My father taught me that one when I was a little boy :-D

dzaima

@Marshall specialization for integers forgetting about needing handling negative args. will fix

rak1507

5:57 PM

Although, to make the challenge potentially harder, I'd say that ⍴⍋⍒,⍟?⍳0 evaluating to 0 is no better than just using lots of ⊢⊢⊢s, and therefore shouldn't be allowed

It would be a lot harder to come up with something with that restriction, but it would also be better in the end as well I think

Adám

@rak1507 How about requiring that no substring evaluates the same?

rak1507

Yeah, every operation has to return a different result

And no intermediate results can be the final result

Adám

@rak1507 it is more than that. Otherwise --------≡⍬ works.

@rak1507 Not only that, no intermediary result can appear more than once.

rak1507

Yeah exactly

Adám

It is almost the same as the substring rule, but the substring rule is much easier state, and allows more interesting solutions.

dzaima

6:03 PM

@Marshall pushed fix

Adám

@rak1507 otoh, it is easier to verify adherence to the intermediary results rule.

Marshall

@dzaima That works.

rak1507

I would say it should be fairly clear if someone's trying to bend the rules, and even if someone does something 'technically' allowed, it isn't in the spirit of the challenge

dzaima

@dzaima (with that, there's minimal runtime benefit, at the cost of double the compile time)

rak1507

43

Q: Biggest Irreducible Hello World

Create a program that outputs Hello, World! The winner is the source code that is the biggest, subject to the constraint that it is irreducible For this challenge, irreducible means there does not exist a program that outputs Hello, World! that can be constructed by removing characters from the...

hello-world code-bowling pristine-programming

Adám

6:11 PM

@rak1507 Yup, that's the one. APL has a respectable score there.

rak1507

Wow, bubblers answer there is absolutely mindblowing

Dyalog APL

7:49 PM

<moon-child> @Adám multiline code blocks: yes, but won't be able to work on it for a few days due to unforeseen circumstances

@Razetime # # # #

Adám

moon-child: if you pull dyalog-safe-exec then the bot will gain a little capability.

TessellatingHeckler

About half way through a line by line transliteration of the BQN "old JS interpreter" into PowerShell. It's going to be fun to debug when it totally doesn't work.

Marshall

@TessellatingHeckler That part is obnoxious. You just have to be patient though. There aren't that many components so pretty soon you'll fix the last bug and be done.