I've just finished watching John Scholes explain a Sudoku solver algorithm in APL and my brain is leaking out my ears but in a good way

@Adám I was typing everything down in RIDE as he said it in the video and I still don't think I got it all XD

@Sherlock9 Well, better late than never :-) Now you have it all in copyable form.

@Adám No I was pausing too. I sort of meant "I don't think I understood even as I typed it" XD I'm still on the line between understanding what's happening and understanding why we're doing it that way and how to apply it elsewhere

box ← {⍵⌿⍵/⍵ ⍵⍴⍳⍵×⍵}
rcb ← {(⍳⍵),¨box⊃⍵*÷2}
⍝ For rcb, why do we need the first element ⊃ of the square root ⍵*÷2?

@J.Sallé Hm, ⊢⍝- isn't what I had in mind, since it isn't really a function you can give a name. Better: -∘0 or ⊢⊣-, no?

@Adám Why is it not a function you can name? It works fine both in TIO and the REPL when I assign it a name.

@J.Sallé But if you inspect the resulting function…

I had -∘0 too but I figured ⊢⍝- was a little more interesting.

@Adám They do turn out to be either only ⊢ or -. I see what you mean.

@Sherlock9 because rcb takes height width as ⍵, and box takes only a single int

@ngn Ohh I'd forgotten that

Thanks!

⎕ ← {{⍵/⍨0=-/¨⍵*2},⍳3⍴⍵} 20

⎕←{{⍵/⍨0=-/¨⍵*2},⍳3⍴⍵}20

@Sherlock9
┌─────┬─────┬───────┬──────┬──────┬───────┬───────┬───────┬───────┬────────┬───────┬────────┐
│3 5 4│4 5 3│5 13 12│6 10 8│8 10 6│8 17 15│9 15 12│12 13 5│12 15 9│12 20 16│15 17 8│16 20 12│
└─────┴─────┴───────┴──────┴──────┴───────┴───────┴───────┴───────┴────────┴───────┴────────┘

Ah there we are. Note to self, avoid extra whitespace

I made a golfy Pythagorean triple generator!

Attempts to turn those dfns into trains are not working yet

)about

@Adám You can evaluate a single line of APL by typing it into chat prefixed by ⍞←. Use ⎕← instead for boxed display and multi-line results and use ⋄ instead to silence the first statement. Use ] to call user commands, including ]help ⍣ for help on a glyph etc. Do not use markdown, but fixed-width (4 initial spaces) is fine. Commands: )lb for language bar, )docs for full documentation, )ref for PDF reference card, )idioms for idiom list.