The APL Orchard

Fmbalbuena

18:00

@Adám 12 bytes, 1 ¯2 ¯3 ¯4 ¯5 ¯6 7

Adám

I can do it in 8.

Fmbalbuena

@Adám what? show me

Adám

⋄ -@1 7-⍳7

TryAPL

@Adám 1 ¯2 ¯3 ¯4 ¯5 ¯6 7

Fmbalbuena

-@1 7-⍳7

-@1 7-1 2 3 4 5 6 7

Adám

18:04

-@1 7 applies - to the elements at indices 1 and 7.

Fmbalbuena

{a lot}¯1 ¯2 ¯3 ¯4 ¯5 ¯6 ¯7

1 ¯2 ¯3 ¯4 ¯5 ¯6 7

@Adám CMC: interpret brainfuck, but

"#" means move the pointer left or right randomly

Adám

When you ping me with a CMC, does that mean you want only me to answer?

Fmbalbuena

No, means you have to solve this

others can solve.

Adám

I don't think you're entitled to dictate what I have to do.

xpqz

@Fmbalbuena dfns.dyalog.com/n_bf.htm

Adám

18:08

@xpqz Fails on the "but".

Fmbalbuena

@xpqz i said but

"*" means increment or decrement

"(" ")" is "[" and "]"

Adám

Not Mini any more.

Fmbalbuena

and lastly "-" is abosulte value

@Adám why? this is probably shorter than the other.

Adám

I don't know what "other" you're talking about.

Fmbalbuena

Can you solve?

Adám

18:10

It is just a matter of adding more lines to the top of what xpqz linked.

'#'≡t:((?2)⊃(lft ⍺)(rgt ⍺))∇ rgt ⍵
'*'≡t:((?2)⊃(inc ⍺)(dec ⍺))∇ rgt ⍵

Fmbalbuena

@Adám ignore "+-[><]"

Adám

In that case, just remove the corresponding lines while replacing [ and ] with ( and )

Fmbalbuena

Full code?

Adám

Give me a couple of mins.

Fmbalbuena

This was inspired by this

hyper-neutrino

18:21

@Adám in case it hasn't been done yet, done

Adám

@Fmbalbuena Try it online! (put your "bf" code in the Input field)

@hyper-neutrino Thanks. (WW did it.)

Fmbalbuena

@Adám WW?

Adám

Wheat Wizard

Fmbalbuena

ok

@Adám input?

Adám

Fmbalbuena

18:24

@Adám I mean input in bf?

Adám

, I think. I'm not a BF expert.

Kamila Szewczyk

, is for input, . is for output.

Brainfuck doesn't have the concept of signed integers.

absolute value is a no-operation.

Adám

@Fmbalbuena Oh, I forgot to add that.

@KamilaSzewczyk But this implementation actually does have them.

Kamila Szewczyk

perhaps, but they're useless.

since multiplication and division algorithms will break

Fmbalbuena

@Adám aplcart.info/?q=Absolute%20value#

Adám

18:27

What are you trying to say?

xpqz

@Adám Clever. Who needs macros, eh?

Adám

Try it online!

Fmbalbuena

LENGTH ERROR
bf[37] get←{_ m _←⍵ ⋄ m}                       ⍝ fetch current value.

Adám

@xpqz I actually use such a technique in production systems. TryAPL for instance.

@Fmbalbuena Did you put any code into the Input field?

Fmbalbuena

@Adám Newline, error

@Adám According to Python 3, A newline in Python means empty string, without raising EOF

Fawn Locke

18:32

That's smart, Adám

Adám

@Fmbalbuena Example run

Fmbalbuena

OK

@Adám Try it online!

Bye

Adám

Yeah, I see that. So it fails on the empty string. Bye!

Fawn Locke

Phew

Fawn Locke

18:45

Who came up with trains?

> and the invention of function trains by Iverson and Eugene McDonnell in 1988.

Nevermind, found it.

Fmbalbuena

19:09

@Adám This seems to return 1 but not, Why? Try it online!

Kamila Szewczyk

this thing in JSON is prefixes of iota 3, not iota of iota 3

Fmbalbuena

@KamilaSzewczyk Try it online!

Kamila Szewczyk

domain error.

what you're describing is

⎕←,\⍳3

TryAPL

@KamilaSzewczyk
┌─┬───┬─────┐
│1│1 2│1 2 3│
└─┴───┴─────┘

Fmbalbuena

@KamilaSzewczyk iota?

Adám

19:18

@Fmbalbuena You want ⍳¨⍳3

Fmbalbuena

@Adám but why this does?

Adám

Because you want to apply ⍳ to each of the numbers in ⍳3

Fmbalbuena

I don't understand

Why this (without each) do?

avx

hi, just a test post.
new to APL within last month.
Have tried pyNapl; and working my way through S. Kruger's Learning APL

Fawn Locke

Awesome! Happy to have you here :)

Fmbalbuena

19:28

@Adám Can you explain every lambda function of sudoku solver in APL (only commands that I understand)?

Adám

No.

Fmbalbuena

> (only commands that I understand)

Adám

@Fmbalbuena ⍳Y generates the indices of an array of shape Y so ⍳⍳3 is ⍳1 2 3 which are the indices of an array with 1 layer, two rows, and 3 columns. Not what you wanted.

@Fmbalbuena I'm not sure what you want me to explain.

Fawn Locke

Adám and, I'm sure, the rest of us are all very busy. You'd most likely learn more by dissecting it yourself, anyway

Adám

I'm trying to play with my children at the same time :-)

Fmbalbuena

19:31

@Adám teach to click the letter "f"?

Adám

No, they know how to do that. They are 8 and 10.

Fmbalbuena

ok

@Adám single question: both know a bit of APL?

Kamila Szewczyk

@Adám will 18.2 have Depth?

Fmbalbuena

@Adám Can you explain dfn of sudoku solver in APL video (only commands that I understand)?

Adám

@KamilaSzewczyk No. Maybe 19.0

@Fmbalbuena "a bit"?

@Fmbalbuena I don't understand what you mean by "(only commands that I understand)".

Fmbalbuena

19:45

@Adám Can you explain dfn of sudoku solver in APL video (only dfns with commands that I understand)?

Adám

So you want me to explain only the inner dfns that consist entirely of functions and operators you've learned?

Fmbalbuena

@Adám yes

@Adám explain rcb dfn

knobo

works:
0=+\¨⌽{⍵,⍺}\2-'JXN'⍳'JJJJJNNJJNNJJJJJ'
works:
1⍳⍨(0 0 0 1 1)
but this does not work:
1⍳⍨0=+\¨⌽{⍵,⍺}\2-'JXN'⍳'JJJJJNNJJNNJJJJJ'

knobo

20:11

it think i solved it.

Fawn Locke

21:26

Is '' an empty character vector?

Richard

Yes I think so.
⍬ is an empty numeral vector, just like 0↑1
And using ]boxing on '' is displayed as an empty square without ~ on the bottom

Alex B

@Fmbalbuena, you will learn much faster by trying to understand on your own. By asking @Adám to help you all the time, you might be giving up the opportunity to push the envelope of your own understanding.

2

Adám

@FawnLocke It is indeed.

Fawn Locke

Thanks guys, just wanted to make sure

Richard

tryinig, yes indeed...

TryAPL

21:34

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

Fawn Locke

My markdown transpiler is working decently :)

Adám

@Richard Only with -s=max but ]display does it, as you are trying to do.

Richard

'⋄ ]display '' '

TryAPL

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

Richard

⋄ ]display ''

TryAPL

21:38

@Richard
┌⊖┐
│ │
└─┘

Richard

⋄ ]display ⍬

TryAPL

@Richard
┌⊖┐
│0│
└~┘

Adám

I just got an idea: A user command ]describe which describes what you give it in human terms. E.g. 'abc' 'def' would say A vector of 2 character vectors

Fawn Locke

That'd be nice

Richard

:)

Adám

21:46

For 19.0 maybe, as a noodle.

Richard

that would be nice. I use ⍴ and ]boxing all the time to understand the output of functions. That's what you meant to do with ]describe? For input and output?

rak1507

sounds like cdecl.org for apl

Fawn Locke

There was a comment yesterday or so about your style guide, and whether or not there was advice for formatting multi-line dfns. I'm also curious about this, and if there's any interest in an auto-formatter for APL code (if it doesn't already exist)

rak1507

@FawnLocke dyalog ide sorta auto formats

Adám

RIDE also has its own formatter.

rak1507

21:48

also has an align comments hotkey

Fawn Locke

Oh, cool. Time to open up ride

Adám

I almost always use the auto-formatting. It barely ever does something I dislike.

Richard

@FawnLocke I might have asked that. But just out of curiousity

Adám

@Richard Input and output are both arrays, so yeah. It could also work on functions and some operators, and on names.

xpqz

@rak1507 wait, it has what now?

rak1507

21:51

not set by default but you can set it

Adám

@xpqz It is numpad / by default, which you probably don't have on your keyboard.

Fawn Locke

How would I start RIDE (from ride) in the browser? tried RIDE_INIT=http:*:4502 -p 4502:4502

Adám

Start RIDE from RIDE‽

]explain ⍤2 would say Derived monadic operator

Fawn Locke

Yeah, how else would I serve ride to the browser?

Richard

@FawnLocke this is I think a parameter when starting Dyalog. I use it to be able to connect to RIDE

Adám

21:53

Yeah you start the interpreter separately with that config, and then point your browser at localhost:4502

Fawn Locke

Ah, okay, gotcha

Woohoo! It works :)

Adám

The whole point is running RIDE without Electron.

Fawn Locke

Oh, I meant from the cli or something

./ride RIDE_INIT=http:*:4502 -p 4502:4502

Using the dyalog interpreter to do that makes more sense, though

Richard

I start Dyalog with "C:\Program Files\Dyalog\Dyalog APL-64 18.0 Unicode\dyalog.exe" RIDE_INIT=SERVE:*:4502

Alex B

I often struggle to debug expressions because I can’t see the intermediate results. If I break down the expression in chunks, sometimes the behavior changes because the context is different. Can anyone suggest how to inspect intermediate results of a long expression?

Adám

21:55

@user8544778 Sorry, I was a bit too busy to welcome you before. Welcome! Since you're new to Stack Exchange chat, I highly recommend having a look at apl.wiki/APL_Orchard#Features

Fawn Locke

⎕← will output the result of any expression (Or from anywhere within an expression)

TryAPL

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

Richard

@AlexB sometimes I manage to insert {⎕←⍵}

Fawn Locke

Heh.

Adám

@AlexB 'tc'⎕CY'dfns' and then insert tc to the right of any function you want to inspect.

Fawn Locke

21:56

Ooo

Alex B

@Adám thanks

Adám

Try it online! Notice how this also shows the order in which the train is evaluated.

Fawn Locke

That's cool

Adám

I'd like to have a way to automatically insert tc everywhere, but it is non-trivial.

Richard

@Adám like 2 + tc 2? instead of 2 + 2

Adám

21:59

Yeah.

Richard

o wow

Can you explaion why and how this works? I just found that ⎕CY is copy workspace. But then I am lost

Adám

tc is a monadic operator. It simply applies its operand as it'd normally be applies, but as a side effect prints that message.

Read about it at dfns.dyalog.com/n_tc.htm

Alex B

Ideally, one should be able to single-step through an expression without altering the code. As cool as the ‘tc’ trick is, it feels like debugging with printf()…

Fawn Locke

Aww no, multi-line dfns don't work with dyalog -script

Adám

@AlexB Agreed. That is a feature of APL*PLUS that I miss by Dyalog.

@FawnLocke They should if you enable multi-line input.

Alex B

22:04

Perhaps a feature for a future release? (hint hint)

Fawn Locke

That makes sense

Yup, thanks

Adám

@AlexB Yes, but my understanding is that it requires quite a lot of surgery on the interpreter. It actually executes token code, not source code.

Richard

yes this is really helpfull. Could be mentioned at dyalog.com/getting-started/tips.htm

Alex B

Understood. Maybe disabling optimizations and translating source symbols into tokens one at the time…? But definitely not trivial.

Adám

@Richard Yes, I just thought of that too. Do you want to email [email protected] with that?

Richard

22:07

Sure

Adám

Ah yes, that's another thing. Some sequences of glyphs become a single token.

Richard

@AlexB something like ]debug on -style=max :)

@Adám just did

Adám

APL*PLUS had a nice tracing interface where it'd highlight each primitive in turn, with separate (optional) windows displaying the (left and) right arguments of that primitive,

rak1507

22:57

tc is nice but I generally just stick with ⎕←

having to put tc everywhere is more of a pain

if there was an automatic way of doing it, that would be great

Adám

It would be quite easy to stick it after each primitive function, but often, that's not what you want. E.g. you want +⌿tc not +tc⌿

rak1507

yeah, good point...

really some tracing debugger like j's dissect is more like what you want

Fawn Locke

yeah

Adám

I wonder how dissect actually works.

Then again, maybe it is possible to do enough syntax analysis to automate insertion of tc.

It could know which glyphs are functions and operators, and insert itself only after the operator in such derived functions.

rak1507

well like you say, it depends on context, maybe sometimes you do want f tc/ and others you want f/tc

Adám

23:03

Instead of altering source code, I'd want something in the IDE like the toggleable stop/trace/monitor bits, but between characters, allowing me to toggle insertion of tc on and off at that interval between two adjacent characters.

Fawn Locke

I wish there was a "100 projects to do in APL" list

Adám

Maybe you'd want to be an intern at Dyalog?

Fawn Locke

Dyalog still does internships?

Adám

Of course.

Fawn Locke

Yeah, I'd be interested

rak1507

23:12

I'd be interested too I think

Adám

Email [email protected] with your CV, and telling about yourself.

Fawn Locke

Cool, will do! Thanks :)

Adám

Don't forget to mention what you've already contributed to the community.

rak1507

If it was this summer, would it mean I couldn't enter the problem solving contest too? (Also, I'll probably be going to uni next year but if I don't would I still count as a student seeing as this is my last year of school?)

Adám

I'm pretty sure that it is fine if you submit before your internship begins were a student when the competition began. I can double-check if you want.

rak1507

23:18

Alright cool thanks

Fmbalbuena

23:36

@Adám Can I write a challenge for you?

Fawn Locke

How the tables turn!

Fmbalbuena

@FawnLocke ?

Fawn Locke

Just a phrase we say in English, a joke :)

Adám

@Fmbalbuena Yes, but no guarantee I'll solve it. If you post CMCs (without pinging me) I might too.

Fmbalbuena

Implement This in APL

Adám

23:39

Why not wait for the main post?

Fmbalbuena

@Adám Because i want to look the sequence and add to my Sandbox post.

Adám

Ah, I see.

@Fmbalbuena Try it online!

Fmbalbuena

Join with ", " please

Adám

Btw, next time you want me to do work for me, say "Hi @Adám can I ask you to do [insert description of work] for me?" instead of pretending it is a challenge for me.

Fmbalbuena

Ok

Adám

23:49

@Fmbalbuena Try it online!

@Fmbalbuena I'm pretty good at handling it, but you should now that the way you write to people often comes across as trying to exploit them.

Fmbalbuena

⋄⍸1 2 4 8

TryAPL

@Fmbalbuena 1 2 2 3 3 3 3 4 4 4 4 4 4 4 4

Fmbalbuena

I understand what does ⍸ do

Adám

Great!

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