The APL Orchard

Fmbalbuena

01:21

@Adám what happens Adám if I stopped using APL

Fawn Locke

You've asked this (pointless) question before

Adám

2 days ago, by Master Quiz

@Fmbalbuena Then You'll notice that APL was just perfect and come back.

Fmbalbuena

@FawnLocke Sorry

> @Adám what happens Adám if I stopped using APL

Adám

You mean to ask what would happen to me?

Fmbalbuena

@Adám a challenge for me (I'll solve tomorrow)

@Adám yes

Adám

01:26

Well, if that also included stopping questions and requests to me about APL, then what would happen to me is that I'd have more time to do other things.

Fmbalbuena

A challenge?

Adám

Generate 1 2 3 1 2 1 2 3 1 2 in 7 bytes.

Fmbalbuena

@Adám Too hard; I will try tomorrow

Adám

Yes, you said that.

Fmbalbuena

(1 2 3) 1 2 (1 2 3) 1 2

Adám

01:29

Yes, there's a pattern.

Fmbalbuena

Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm ok

LdBeth

03:24

10⍴5⍴⍳3

Razetime

might wanna delete that so fmbalbuena doesn't get spoiled

LdBeth

I hope he/she would back to here after solved the puzzle.

Razetime

i do not expect them to solve it if they find an answer here

PyGamer0

04:21

what does ⍸ do?

@Adám i guess that really happens since now i want some APL features built-in into python lol

Fawn Locke

It's most often used to turn a bit mask into a set of indices

⎕←⍸0 1 1 0 1

TryAPL

@FawnLocke 2 3 5

Razetime

@PyGamer0 monadic or dyadic?

dyadic is a binary search

Fawn Locke

xpqz recently added a new section to his book dedicated to it

PyGamer0

@Razetime does it presume the input is sorted?

Razetime

04:24

monadic repeats indices by truthy values

user

It’s like iota but with multiple indices (dyadic)

Fawn Locke

xpqz.github.io/learnapl/…

Razetime

@PyGamer0 check the docs for that

i don't use interval index much

PyGamer0

05:13

how to get a specific row from a matrix? (i want the second row io is 1)

Razetime

⌷

PyGamer0

is that the squished quad?

Razetime

yes

PyGamer0

05:29

ok i finished converting Fmbalbuena's python code to apl

in Saving TIO links for later, 1 min ago, by PyGamer0

Try it online!

Alex B

08:42

@LdBeth in 6: ,⍨5⍴⍳3

Richard

08:59

or like this
m[2;]

avx

09:21

@Adám thanks.

Adám

09:51

@avx So, are you new to APL, or an established user? APL has certainly been using AVX for a while now :-)

xpqz

@avx Let me know what you think of the book; always looking to improve it. Did you watch my talk from the Dyalog '21 conference?

Kamila Szewczyk

CMQ: what is the most beautiful/characteristic APL glyph?

xpqz

⍨

Fawn Locke

I was thinking the same thing

Adám

If they gave out shirts with glyphs, I'd go for ⍨

xpqz

10:02

I like all the diaresis ones, e.g.⍣

...apart from under.

Adám

Pareidolia

Pareidolia (; also US: ) is the tendency for perception to impose a meaningful interpretation on a nebulous stimulus, usually visual, so that one sees an object, pattern, or meaning where there is none. Common examples are perceived images of animals, faces, or objects in cloud formations, seeing faces in inanimate objects, or lunar pareidolia like the Man in the Moon or the Moon rabbit. The concept of pareidolia may extend to include hidden messages in recorded music played in reverse or at higher- or lower-than-normal speeds, and hearing voices (mainly indistinct) or music in random noise, such...

Fawn Locke

⍤ when used in it's atop form always makes me whince, completely irrational. I sometimes will write (f g) instead of f⍤g to avoid it

Adám

What do you have against Ewoks‽

xpqz

I think it looks like a little piggy face.

Adám

'tis a paw print.

Fawn Locke

10:04

What's weird is that f⍤A looks okay. It's probably because I feel like I use f⍤g too much

/shrug

Adám

@KamilaSzewczyk Objectively speaking, ⎕ is the most beautiful.

Kamila Szewczyk

but the least characteristic

Fawn Locke

I also like ⌽

⍋ too

Kamila Szewczyk

i've had people ask me if this is a literal square or their font is missing some chars

xpqz

Yeah, all the time..

Adám

10:06

Block of tofu.

Kamila Szewczyk

lol

Razetime

@KamilaSzewczyk i like ∇

Adám

Not kidding though. The phenomenon of computers showing ⎕-like shapes for missing chars is called tofu.

Fawn Locke

Oh, cool

I think ⊆ is characteristic of APL

More so than any other glyph imo.

Adám

But it is used in TMN!

Fawn Locke

10:08

That's true..

Adám

Actually, almost all APL's glyphs are used other places, except the ones that are overstrikes with ¨ or ⎕

Fawn Locke

I learned of ⊆ from APL before TMN, when I saw them I was certain mathematicians were using APL unicode for convenience

Adám

heh

@KamilaSzewczyk ⍟

Fawn Locke

⍛ is a nice figurehead for APL's function composition. That's almost a pun :)

Adám

How so?

Fawn Locke

10:13

`⍛` looks like the head of a figure

`⍛
/ | \

Adám

Split your message in two.

Fawn Locke

This works, will do in the future

Kamila Szewczyk

@Adám APLcart suggestion: an intersperse/insert between function?

Fawn Locke

I suppose they all sort of do, ⍤ even has eyes

Kamila Szewczyk

⎕←' '(≢↓∘∊,¨)'hello'

TryAPL

10:15

@KamilaSzewczyk h e l l o

Fawn Locke

I have searched for such a function on multiple occasions

Another suggestion:

⋄ {(1,⍨2⍲/⍵)/⍵}1 1 1 1 0 0 0 1 1 1 1

TryAPL

@FawnLocke 1 0 0 0 1

Fawn Locke

Collapsing sequences of 1's

Adám

Ah, that's nice.

Fawn Locke

⋄ 1 0 0 1 0 1 0 0 ((+⍀1⍪2≢⌿⊣)⊆⊢) 'Sequence' ⍝ This is a function I've found useful during my Markdown project

TryAPL

10:20

@FawnLocke
┌─┬──┬─┬─┬─┬──┐
│S│eq│u│e│n│ce│
└─┴──┴─┴─┴─┴──┘

PyGamer0

is there a public dyalog roadmap?

Adám

Every year.

@KamilaSzewczyk So something like ⎕← 'XYZ' {⍺{⍺⍴⍨≢⍵}@{(|m)/(m<0)}⍵⍀⍨m←1(-≢⍺)⍴⍨¯1+2×≢⍵} 'hello'

TryAPL

@Adám hXYZeXYZlXYZlXYZo

Adám

Can be cleaned up a little.

Arrg, I always forget the silliness of @

The point is that it works for nested and high-rank arrays:

⋄ '_¯' {⍺{⍺⍴⍨≢⍵}@(⍸(|m)/m<0)⊢⍵⍀⍨m←(¯1+2×≢⍵)⍴1,-≢⍺} ⍥⍪ 'Boo'

TryAPL

@Adám
B
_
¯
o
_
¯
o

Fawn Locke

10:27

Nice :)

Adám

@FawnLocke So "cut on every change"? Wouldn't it make more sense to have a general "indicate the beginning of every run or identical elements"?

Fawn Locke

Yeah, I suppose it would

Kamila Szewczyk

@Adám looks great

but if we made it work just on 1d arrays as an alternative, it could be much smaller.

Adám

How so?

Kamila Szewczyk

⎕←0{↑,/(1↑⍵),⍺∘,¨1↓⍵}⍳5

TryAPL

10:38

@KamilaSzewczyk 1 0 2 0 3 0 4 0 5

Kamila Szewczyk

alternatively with ↑,/ becoming ∊.

Fawn Locke

⋄ 'XYZ' {⊃(⊣,⍺,⊢)/,¨⍵} 'hello'

TryAPL

@FawnLocke hXYZeXYZlXYZlXYZo

Kamila Szewczyk

oh, that's smart too.

      cmpx 's1 {∊(1↑⍵),⍺∘,¨1↓⍵} s2' 's1 {⊃(⊣,⍺,⊢)/,¨⍵} s2'
  s1 {∊(1↑⍵),⍺∘,¨1↓⍵} s2 → 6.9E¯6 |    0% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕
  s1 {⊃(⊣,⍺,⊢)/,¨⍵} s2   → 1.9E¯5 | +180% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕


      ⎕⎕⎕

my solution seems faster though

Fawn Locke

This function is already in the APLCart btw, the point here is definitely the multi-dimensional aspect

⋄ (⊂'XYZ') (,/1↓∘,,⍤0) 'hello'

Kamila Szewczyk

10:42

oh?

i couldn't find it

TryAPL

@FawnLocke
┌─────────────────┐
│hXYZeXYZlXYZlXYZo│
└─────────────────┘

Fawn Locke

Well, except the ,/

Kamila Szewczyk

"insert between" and "intersperse" don't yield anything

Fawn Locke

it's join with separator I believe

Adám

@KamilaSzewczyk You were saying?

      cmpx 's1 {⍺{⍺⍴⍨≢⍵}@(⍸(|m)/m<0)⊢⍵⍀⍨m←(¯1+2×≢⍵)⍴1,-≢⍺} s2' 's1 {∊(1↑⍵),⍺∘,¨1↓⍵} s2' 's1 {⊃(⊣,⍺,⊢)/,¨⍵} s2'
  s1 {⍺{⍺⍴⍨≢⍵}@(⍸(|m)/m<0)⊢⍵⍀⍨m←(¯1+2×≢⍵)⍴1,-≢⍺} s2 → 4.8E¯5 |     0% ⎕⎕⎕
  s1 {∊(1↑⍵),⍺∘,¨1↓⍵} s2                            → 1.2E¯4 |  +150% ⎕⎕⎕⎕⎕⎕⎕
  s1 {⊃(⊣,⍺,⊢)/,¨⍵} s2                              → 6.7E¯4 | +1296% ⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕⎕

Fawn Locke

10:43

Those could be good keywords

Heh.

Kamila Szewczyk

@Adám lol

nice

Adám

Stay flat.

This should be the APLers' greeting: "Keep it flat!"

⍀ might be the most under-appreciated APL function.

@FawnLocke Adding those.

Fawn Locke

Awesome :)

Definitely under-appreciated for it's utility

Alex B

@xpqz I was not aware of this book (I'm new to APL). I started reading a few paragraphs. Very nice, so far. Thank you!

Adám

@FawnLocke That high count it probably due to scan, not expand.

Fawn Locke

10:53

I will update these results sometime this week with checks such as those, it's been on my mind

Adám

How can you check if a slash is being used as fn or op?

Fawn Locke

Well, I can check if the next glyph is a primitive function with a ∊ it's not perfect but it'll help separate the cases

I could possibly also try to find the definitions of names but that feels out of scope for this

Might be fun to try!

rak1507

@FawnLocke ⊢⊂⍨1,2∨/⊣ works too I think

Fawn Locke

Nice

avx

11:26

@KamilaSzewczyk I found this really interesting dl.acm.org/doi/pdf/10.1145/3315454.3329960

xpqz

12:57

The "Melt nested array" challenge from codegolf.meta.stackexchange.com/questions/2140/… was fun as an APL task.

      melt data
┌→──────────────────────────────┐
↓[1,                       ,2,3]│
│   [1,                   ]     │
│      [8,2,     ,5,4,   ]      │
│           [1,2]     [9]       │
└───────────────────────────────┘

Adám

@xpqz Wrong link?

Fawn Locke

^

xpqz

0

A: Sandbox for Proposed Challenges

Melt a nested array code-golf array ascii-art string ragged-list When I look at a ragged-list like [1,[1,[8,2,[1,2],5,4,[9]]],2,3], I sometimes mentally imagine the list melting into goo and dropping like from the edge of a table, going further down in the deeper-nested parts of the list. [1, ...

Too late for edit, sorry

Adám

Seems almost trivial with input as JSON.

rak1507

I have a 33 just with the string

⋄{⍉↑⍵↑¨⍨-(']'=⍵)++\1 ¯1 0['[]'⍳⍵]}'[1,[123,[8,2,[1,2],5,4,[9]]],2,3]'

TryAPL

13:02

@rak1507 Did you forget to add backticks around your code (`⋄ code`)? You can edit your message and I will edit my reply.

rak1507

⋄ {⍉↑⍵↑¨⍨-(']'=⍵)++\1 ¯1 0['[]'⍳⍵]}'[1,[123,[8,2,[1,2],5,4,[9]]],2,3]'

TryAPL

@rak1507
[1,                         ,2,3]
   [123,                   ]
        [8,2,     ,5,4,   ]
             [1,2]     [9]

xpqz

Nice!

rak1507

seemed like ⎕JSON⍠'M' would be ideal for it but having to have the commas + closing brackets makes it more annoying

xpqz

Mine was considerably longer, and not nearly as clever.

melt←{
  d[1+⍸2>/d←+\-⌿'[]'∘.=⍵]+←1
  ⍵@(↓⍉↑(¯1+d)(⍳≢⍵))⊢(⌈/d)(≢⍵)⍴' '
}

Adám

13:07

Here's mine: ⋄ {⍉↑⍵↑⍨¨+\-⌿↑(0,']'=¯1↓⍵)('['=⍵)}'[1,[1,[8,2,[1,2],5,4,[9]]],2,3]'

TryAPL

@Adám
[1,                       ,2,3]
   [1,                   ]
      [8,2,     ,5,4,   ]
           [1,2]     [9]

Adám

I think it can be shortened a little.

xpqz

Did you have a JSON-based idea?

Adám

That's the one. Input as JSON, but don't use ⎕JSON

xpqz

Oh I see what you mean.

Adám

13:13

This really needs BQN's »

PyGamer0

what does that do?

Adám

Monadic just pushes one fill element in from the left, dropping off the rightmost element.

A little shorter: ⎕← {⍉↑⍵↑⍨¨+\('['≠⍵)-']'≠'[',¯1↓⍵}'[1,[1,[8,2,[1,2],5,4,[9]]],2,3]'

TryAPL

@Adám
[1,                       ,2,3]
   [1,                   ]
      [8,2,     ,5,4,   ]
           [1,2]     [9]

Adám

@PyGamer0 Dyadic lets you specify which elements to push in (even more than one). So '[',¯1↓⍵ would be '['»⍵

Razetime

13:59

@xpqz codegolf.stackexchange.com/questions/6600/topographic-strings is really close

Fmbalbuena

@Adám Hey

10⍴5⍴⍳3

Adám

Very nice.

Fmbalbuena

(I exactly found a solution of this message)

Razetime

i told you @LdBeth

Fmbalbuena

11 hours ago, by LdBeth

10⍴5⍴⍳3

PyGamer0

14:02

lol

Fmbalbuena

@Razetime No, I found a solution, Then i joined, Finding Adám message. But i found this.

PyGamer0

@Adám ? link?

Fawn Locke

Is there a simple way for a function to make a parent function return early?

Razetime

is this about dfns

Fawn Locke

Yeah

Adám

14:04

@PyGamer0 apl.wiki/Morten_Kromberg#Road_Map_presentations

@FawnLocke Can you give an example?

Fawn Locke

I know you could just return 0 and then wrap a guard around that, curious if there's another way. Sure, one second

Adám

It doesn't sound very functional, as supposedly functions shouldn't have sideeffects.

Alex B

@Fmbalbuena ,⍨5⍴⍳3

Fawn Locke

TopLayer ← {
    v ← {⍺:ReturnEarly⋄SomeResult}
    LaterExpression v
}

Adám

@Fmbalbuena Can you generate 1 2 3 4 1 in 4?

Fawn Locke

14:06

Preferably ReturnEarly would stop LaterExpression from being reached

Adám

v needs an argument.

Fawn Locke

So, I'd just make ⍺:0 and then wrap a guard around that?

Adám

Ah, so you want v to either cause TopLayer to quit, or feed a value to LaterExpression?

Fawn Locke

Yes

Adám

I think it can be hacked together, but it won't be pretty.

However, what should TopLayer return if we return early?

Fawn Locke

14:09

⍵, also It's okay, I realized my code had repeating concepts so I tried to create operators to abstract them, guards have got in the way :)

Alex B

14:30

@avx thanks for sharing. I will read it during the weekend.

Fmbalbuena

14:43

@Adám ⋄5⍴⍳4

TryAPL

@Fmbalbuena 1 2 3 4 1

Adám

Well done.

Fmbalbuena

@Adám a challenge: 99998 99994 99976 99880 99280 94960 59680 ¯262880 in 12 bytes. (Hard)

@Adám How to clear the workspace in TryAPL?

PyGamer0

@Fmbalbuena )clear ws?

Fmbalbuena

@PyGamer0 This prints clear ws

Not sure

      ⎕←'bla bla'
bla bla
      )clear
clear ws
      )clear ws
clear ws
      clear ws
VALUE ERROR: Undefined name: ws
      clear ws
            ∧

TryAPL

14:53

@Fmbalbuena bla bla

PyGamer0

@Fmbalbuena then it works, it removes all defined variables from the workspace

Adám

@Fmbalbuena Do you want to remove all definitions or clear the screen?

Fmbalbuena

clear the screen

Adám

F5

Fmbalbuena

I mean code to clear the screen

Adám

14:56

You can't. The APL code cannot break out of the sandbox. You can, however, push everything away with 0/⍪100⍴⍬

Fmbalbuena

@Adám execute cls in Bash?

Adám

⎕SH'cls' won't work.

Fmbalbuena

ok

@Adám How to use :Repeat without ∇?

Fawn Locke

@Fmbalbuena (999999-(+\⊢×!))⍳10

Not quite 12

Fmbalbuena

@FawnLocke You need 1⍨-10*n, right?

Fawn Locke

15:03

I just hardcoded it, but that'd be shorter, yeah

Fmbalbuena

@Adám Is allowed to press "del" until everything is empty?

Razetime

@Fmbalbuena you can't

label related stuff is tradfn only

Fmbalbuena

@Razetime If statements?

Razetime

check aplcart

Fmbalbuena

@Razetime ?

Razetime

15:10

aplcart.info

Fmbalbuena

@Razetime aplcart.info/?q=check#

xpqz

Raze meant "check aplcart [for repeat]", I suspect.

Fmbalbuena

aplcart.info/?q=for%20repeat#

xpqz

You can learn about the "power" operator ⍣, maybe.

Fmbalbuena

⋄1 2⍣+3

TryAPL

15:13

@Fmbalbuena
LENGTH ERROR
      1 2⍣+3
           ∧

xpqz

⎕←{⍵+1}⍣5⊢1

TryAPL

@xpqz 6

xpqz

@Fmbalbuena you can read about it here: xpqz.github.io/learnapl/iteration.html#power

⎕←(1∘+⍣3) 5

TryAPL

@xpqz 8

Kamila Szewczyk

@Fmbalbuena hmm

fun

Fmbalbuena

15:32

@KamilaSzewczyk This is hard

Fmbalbuena

15:44

@xpqz ⋄{⍵×2}⍣100⊢2 correct?

TryAPL

@Fmbalbuena 2.5353012E30

Fmbalbuena

@Adám when you join this room, I have a question: Can you define a function that checks if the left argument exists, return 1 else 0.

xpqz

@Fmbalbuena It multiplies by 2, 100 times. You can see the intermediate steps by ⋄{⎕←⍵×2}⍣10⊢2

TryAPL

@xpqz
NOT PERMITTED: Illegal token
      {⎕←⍵×2}⍣10⊢2
     ^

Fmbalbuena

TryAPL don't allow

xpqz

15:50

    {⎕←⍵×2}⍣10⊢2
4
8
16
32
64
128
256
512
1024
2048

Fmbalbuena

@xpqz Sometimes i want 2 f 2 f 2 f 2.

Is this possible with ⍣?

xpqz

Can you show an example function f?

Fmbalbuena

@xpqz f←{⍺+⍵×2}

xpqz

      2∘f⍣3⊢2

30

Fmbalbuena

⋄2∘{⍺+⍵×2}⍣3⊢2

TryAPL

15:56

@Fmbalbuena 30

xpqz

Yup.

Fmbalbuena

and a function with a operator?

f←{⍺ ⍵⍵ ⍵ + ⍺}⋄g←{⍺+⍵×2}

@xpqz

xpqz

Your dop needs to be f←{⍺ ⍺⍺ ⍵ + ⍺}

Fmbalbuena

sorry

xpqz

      2∘(g f)⍣3⊢2

58

Fmbalbuena

16:00

@xpqz 2 g f 2 g f 2?

xpqz

One more: 2 g f 2 g f 2 g f 2

(that's the 3 bit)

Fmbalbuena

@xpqz is ⍣ your favorite operator?

xpqz

If I have to pick just one, I'd pick Rank (⍤) ahead of Power.

Fmbalbuena

⍤

@xpqz ⋄5⍳⍤5

TryAPL

@Fmbalbuena
SYNTAX ERROR: Missing right argument
      5⍳⍤5
       ∧

xpqz

16:07

You'll need to read up a bit on Rank; there's a whole chapter complete with some drills in the book: xpqz.github.io/learnapl/rank.html

Fmbalbuena

@xpqz OK, not now.

Kamila Szewczyk

16:31

@Fmbalbuena {2=⎕nc'⍺'}

Fmbalbuena

@KamilaSzewczyk explain

Kamila Szewczyk

⎕nc yields you what is the thing that you passed as the right argument.

it happens to return 2 if it's a thing, and 0 if it's not

Fmbalbuena

@KamilaSzewczyk why 2 and 0, not 1 and 0?

Kamila Szewczyk

ask Dyalog.

microapl.com/apl_help/ch_020_070_470.htm

maybe this documentation explains.

Fmbalbuena

I forgot ternary if statement

Kamila Szewczyk

16:37

in APL?

Fmbalbuena

yes

Kamila Szewczyk

i don't think there's a ternary operator equivalent in APL unless you make it with guards.

Fmbalbuena

{5:1=⍵?3}

Fawn Locke

There is

Fmbalbuena

@FawnLocke 3 is There

Fawn Locke

16:38

As per the aplcart: X⊣⍣Bs⊢ Ternary: if Bs then return X else return Y

Fmbalbuena

{⎕nc'⍺'=2
:⍺+⍵
⋄⍳⍵}

@KamilaSzewczyk ^

Fmbalbuena

17:39

@Adám run APL in vs code?

pmikkelsen

18:17

Do you know of any good reads for someone who wants to write his own APL interpreter? Conformance to the standard or other APL implementations is not a strict requirement

dzaima

@pmikkelsen aplwiki.com/wiki/Implementation_resources

pmikkelsen

Thanks

Kamila Szewczyk

@Adám what algorithm does Dyalog use for factorials?

Richard

19:22

Why is this giving a rank error?

{⍵+/⍨¨⍳⍴⍵}¯2 1 ¯3 4 ¯1 2 1 ¯5 4

And this one not

{⍵+/⍨4} ¯2 1 ¯3 4 ¯1 2 1 ¯5 4

I'm trying to do this operation for each 1 .. n where n is the size of ⍵

Master Quiz

20:17

@Richard You have to enclose the right argument to do an iteration on the left argument (at least this is what I do) ⋄{(⍳⍴⍵)+/¨⊂⍵}¯2 1 ¯3 4 ¯1 2 1 ¯5 4

TryAPL

@MasterQuiz
┌─────────────────────┬───────────────────┬───────────────┬────────────┬──────────┬────────┬──────┬────┬─┐
│¯2 1 ¯3 4 ¯1 2 1 ¯5 4│¯1 ¯2 1 3 1 3 ¯4 ¯1│¯4 2 0 5 2 ¯2 0│0 1 2 6 ¯3 2│¯1 3 3 1 1│1 4 ¯2 5│2 ¯1 2│¯3 3│1│
└─────────────────────┴───────────────────┴───────────────┴────────────┴──────────┴────────┴──────┴────┴─┘

Master Quiz

Does someone know how to use APL on VS Code? The extension APL Language is working, but APL Language Server Client isn't; may be this condition The language server requires a copy of Dyalog v17.0, but I don't think so...

Richard

21:09

@MasterQuiz thanks, seems I still miss some basic knowledge...

Richard

21:26

Ah, I think I got it.
Is it because +/ is a scalar operator which splits up ⍵? Wether is on the left or the right argument?

And/or ¨ can also work on the other side of the function, like

1 2 3 ,¨ 99

Master Quiz

22:31

An example with Reverse:
If you want to reverse a vector by one, two, and three, you would like to do an each on the left argument, but you can't. So you do something like this, to iterate on the left argument `1 2 3⌽¨⊂⍳4`

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