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ngn

05:22

The "Weaver" challenge looks like it has potential for being won in APL with Amend (@).

Adám

06:11

@ngn "At".

ngn

@Adám is that its official name?

Adám

@ngn Yes‌.

ngn

@Adám I'm so close to beating Jelly...

@Adám uh, "Authentication Required"

Adám

@ngn Sorry, change that 7 to a 6.

6 hours later…

Erik the Outgolfer

12:10

@Adám ah, while APL\360 has limited support for arrays, it looks like '' serves as the (1-dimensional) empty array for both numbers and characters

Adám

@EriktheOutgolfer No, '' is the empty character array. Zilde (⍬) was added later for convenience. You had to use (0⍴0).

ngn

empty array jokes starting in 3... 2... 1...

Erik the Outgolfer

@ngn it's not very funny...

Adám

@EriktheOutgolfer But, you were allowed to catenate empty arrays of different prototypes.

@ngn More like: Empty array jokes starting in IV, III, II, I,

ngn

@EriktheOutgolfer of course, nobody's told any yet :) <- empty array joke

@Adám why Roman?

Erik the Outgolfer

12:14

@Adám and it looks like the right argument's prototype is used for the result

Adám

@ngn — That's outrageous! Down on the corner, they are only $3 each. — So why don't you buy there? — They're sold out. — Madam, when we're sold out, they're only $2 each!

Erik the Outgolfer

@Adám marketing against APLers 101

ngn

@Adám :D thumb up

Adám

@EriktheOutgolfer Yes, Dyalog APL is different from all other APLs in that regard.

@ngn !

ngn

@Adám well, yeah... I had a distorted understanding of APL arrays at the time. Too hard to fix without a rewrite.

Erik the Outgolfer

12:18

@ngn I guess that has to do with versioning of vintage APL variants

ngn

@EriktheOutgolfer hm... or the lack of 0 in Roman numerals

Adám

@EriktheOutgolfer This may have your interest.

Erik the Outgolfer

> one vendor chooses the left, and all the others the right

hm, maybe Dyadic Systems?

Adám

@EriktheOutgolfer How did you guess?

Erik the Outgolfer

@Adám well, because that's what exhibits such behavior

Adám

12:23

@EriktheOutgolfer Not because I just told you?

Erik the Outgolfer

@Adám well, I had actually tried before...

Erik the Outgolfer

13:14

18 hours ago, by Adám

@EriktheOutgolfer Programmers had to be clever instead. Here is a challenge for you: Given N, return ∊⍳¨⍳N.

@Adám done:

      ∇R←II N;I
[1]   I←⍳N
[2]   R←0⍴0
[3]   R←I,R
[4]   I←¯1↓I
[5]   →3×1≤⍴I∇
      R N

Adám

@EriktheOutgolfer Yuck, no stinking loops!

@EriktheOutgolfer I mean, good job.

Erik the Outgolfer

@Adám hehehe

well, unfortunately that's the 60s :P

Adám

@EriktheOutgolfer No, you're supposed to solve it without using any looping.

Ven

.oO( any loop can be replaced with a reduce, if you're ngn enough )

Erik the Outgolfer

@Ven (no nested arrays)

Adám

13:16

@Ven APL\360 did not support reductions with user defined functions.

Erik the Outgolfer

and I think that reductions are a form of looping anyway

ngn

@EriktheOutgolfer in that spirit + is a form of looping too

Erik the Outgolfer

@ngn hm, I'm not sure what Adám means by "no looping", since I doubt it would be possible without /

ngn

@Adám can we use ,\ ?

Erik the Outgolfer

@ngn APL\360 doesn't have that...

ngn

13:28

@EriktheOutgolfer huh... what about ∘.< ?

Erik the Outgolfer

@ngn yes it does have that

< is a scalar function

however, ,\ would obviously result in a nested array, which is just too much for ye olde APL\360

ngn

@EriktheOutgolfer a very roundabout way: (,(⍳N)∘.≥⍳N)/,N N⍴⍳N

Erik the Outgolfer

@ngn sorry, but that's Dyalog, not APL\360 :P

ngn

@EriktheOutgolfer This is basic APL stuff. Maybe stranding was missing? N N -> (N,N)

Erik the Outgolfer

@ngn ah, thought that was a train...

Adám

13:45

@ngn Nicely done!

ngn

@Adám I'm sure there must be a shorter way

Adám

@ngn Not code-golf.

Erik the Outgolfer

@Adám uh...except that / does not exist as a function in APL\360

Adám

@EriktheOutgolfer Doesn't the expression work? It was an operator which took a Boolean array as operand.

Erik the Outgolfer

@Adám oh it was‽ I thought it didn't exist at all, that's why I used filthy → there

Adám

13:52

@EriktheOutgolfer @ngn Now do ∊⍳¨N

ngn

@Adám N is a vector?

Erik the Outgolfer

@Adám ⍳N

Adám

@ngn Yes.

Erik the Outgolfer

huh, N is apparently a vector

(yes, I saw that coming...)

ngn

@Adám do we have A~B ?

Adám

13:58

@ngn Nope, but you can easily write that.

ngn

oh, this is so ugly I shouldn't even post it

(,N∘.≥⍳⌈/N)/,((⍴N),⌈/N)⍴⍳⌈/N

Erik the Outgolfer

@ngn lol just make a tradfn and use local variables

ngn

if that's better:
M←⌈/N
(,N∘.≥⍳M)/,((⍴N),M)⍴⍳M

Erik the Outgolfer

@ngn you can also assign in-place, but I like doing things more orderly :)

(because that totally wasn't my approach)

Adám

@ngn Precisely! Your solution is identical to the "official" answer.

ngn

14:08

the stone age of APL...

Erik the Outgolfer

@Adám @ngn now do ∪V for a vector V

ngn

@EriktheOutgolfer (∨⌿<\∨\V∘.=V)/V

Adám

@EriktheOutgolfer ((V⍳V)=⍳⍴V)/V

Erik the Outgolfer

@Adám did you copy-paste that comment from SO? :P nice

ngn

@Adám wait... it had dyadic iota?

Adám

14:21

@EriktheOutgolfer It is a classic idiom.

@ngn Yes, that's original.

@EriktheOutgolfer I think all the FinnAPL idioms work on APL\360. (Though you have to be explicit about ⎕IO. System functions were not invented yet.)

Erik the Outgolfer

@Adám @ngn next task: X∩Y for two vectors X and Y (and no, ∩ doesn't exist in APL\360)

Adám

@EriktheOutgolfer (X∊Y)/X

Erik the Outgolfer

@Adám hm, looks like you realized that quickly

Adám

@EriktheOutgolfer I grew up with APL*PLUS/PC which was not much more than APL\360. The "PLUS" was system functions and / and \ could take positive integers, not just Booleans. I think that was basically it.

2 hours later…

Feeds

16:41

Just a reminder that Dyalog servers will be down for maintenance tomorrow starting at 9am UTC. We expect this to last approximately 4 hours during which time our website and other external services will be unavailable.

Tweeted by dyalogapl on April 23, 2018 at 3:54 PM

Erik the Outgolfer

17:08

@Adám uh, doesn't \ exist in APL\360? and you can't make tradops and dops, right?

2 hours later…

Adám

19:15

@EriktheOutgolfer \ exists, but only as scan with scalar functions and as expand with Boolean left operand.

@EriktheOutgolfer No user defined operators, and no d-anything.

Pavel

@Adám What's the d-anythings?

Erik the Outgolfer

@Adám but I tried +\1 2 3 (with Shift+/, not the \ key directly) and it didn't work

Adám

@Pavel dops and dfns.

Pavel

What's a dop?

Adám

@Pavel A user defined operator using the {…} style.

Pavel

19:21

Adám

@EriktheOutgolfer That should work.

Erik the Outgolfer

@Adám but it's a syntax error

      -?1 2 3
      syntax error
      -? 1 2 3
      )

  +\1 2 3
  SYNTAX ERROR
  +\ 1 2 3
  ^

more like that really

1 hour later…

Adám

20:41

@EriktheOutgolfer Right, Morten seems to recall Scan being a later addition, and indeed, I can't find it in the reference manual.

FrownyFrog

If I want to do (⍳≢⍵) with scan, is that (≢¨,\⍵)? Can I compose ≢ and , somehow?

Adám

@FrownyFrog No, because the , is what creates the prefixes and only when the entire prefix is ready are you ready measure its length.

@FrownyFrog Can you use +\=⍨ instead?

⍞←+/=⍨'abcde'

Dyalog APL

@Adám 5

Adám

⍞←+\=⍨'abcde'

Dyalog APL

@Adám 1 2 3 4 5

FrownyFrog

20:50

wow cool

Of course, , is applied several times

I get it now

Adám

21:01

@DevelopingDeveloper Welcome. Interested in learning APL?

1 hour later…

DevelopingDeveloper

22:17

@Adám Hey @Adám I am! I have tried to sign-up for your classes a few times and got stuck with a meeting at work during that time and was unable to make it. Do you have any upcoming classes scheduled? I seem to have lost the link which I found to see the class schedule times

Adám

@DevelopingDeveloper You don't need to sign up, but if you want reminders, then you can. When a class is scheduled, the sign up page is here. You can read transcripts of past classes here. I usually have classes every Wednesday at 17:30 UTC, but after almost 40 hours of lessons, I've run low on stuff to teach. Any ideas?

DevelopingDeveloper

@Adám Awesome, thank you for sending me this. Let me look through some of the transcripts and see what I can pick up from those and go from there

Adám

@DevelopingDeveloper Feel free to ask anything anytime. Do you have an APL interpreter installed?

DevelopingDeveloper

23:00

@Adám No sir I do not, the small amount of APL I have done has been using TIO

Adám

@DevelopingDeveloper OK, while I recommend getting a free personal license you can also use TryAPL for an interactive session (REPL) more akin to the offline experience, or use the chat bot here for single stand-alone lines:

⎕←⍳2 3

Dyalog APL

@Adám
┌───┬───┬───┐
│1 1│1 2│1 3│
├───┼───┼───┤
│2 1│2 2│2 3│
└───┴───┴───┘

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