The APL Orchard

rak1507

12:20 AM

@LdBeth I wonder what it's for

LdBeth

1:34 AM

@rak1507 It's something you'd have on a lisp machine, parsing various kinds of time/date text formats

rabbitgrowth

7:01 AM

Trying to make {⍸2=+⌿0=∘.|⍨⍳⍵} tacit. Managed to turn it into ⍸2=(+⌿0=∘.|⍨∘⍳), and then ⍸2=∘(+⌿)0=∘.|⍨∘⍳. But is there a way to get rid of the parens altogether?

Fawn Locke

No, I don't think so

You can use an old golfer's trick

⍸2=1⊥0=∘.|⍨∘⍳

1⊥ is summation here and continues the forks :)

rabbitgrowth

Ah lovely, thank you

I was assuming it was always possible to write a train parens-free

"Decode in base 1" - that's quite clever :)

Fawn Locke

7:21 AM

Or ⍸2=0+.=∘.|⍨⍤⍳

∘.|⍨⍤⍳ and ∘.|⍨∘⍳ are identical semantically (when monadic), but i find the former nicer to think about.

rabbitgrowth

What do you mean by "nicer to think about"? Aren't they exactly the same in the monadic case?

I've been going to ∘ by default because it looks simpler visually (which is probably not the best reason to choose something).

I'm not sure if I'm thinking about this in the proper way, but f⍤g feels like it's doing something simpler in the dyadic case: apply g to the arguments, then apply f to the result of that.

Whereas if you were to describe f∘g in words, it would be more of a mouthful.

Fawn Locke

7:41 AM

Back, ⍤ is "atop" in my brain, f (g X). So using ∘ for it feels wrong, I prefer to think about it as a lapse of judgement on Dyalog's part

∘ is a nicer symbol for atop anyway, but It'll have nice symmetry with before once that's added (⍛)

Well Dyadically they are different, f (X g Y) vs X f (g Y)

The former being ⍤ and more atop-y, hence the association

Dyalog should've made monadic ∘ Y f (g Y) imo

rabbitgrowth

Would monadic ⍥ be (g Y) f g Y then?

Fawn Locke

Probably not, I haven't thought about what it should be. I think ⍥ is atop monadically in BQN too - which feels like a mistake

But there isn't much it can be

I very rarely see f⍥g⍨ Y

rabbitgrowth

8:02 AM

Anyway, I think I'm starting to grok tacit. Sometimes I can immediately recognize that I want a ⍥, etc, although it can still take me some time to figure out where to put what exactly.

where to put what? what to put where?

Anyway, yeah. The progress feels nice.

Fawn Locke

Yes, I forgot to say that. You've picked it up extremely quickly

rabbitgrowth

I've been learning on and off for more than a year actually. This is what got me interested: reddit.com/r/adventofcode/comments/k8zdx3/…

Thought it was garbled text at first :)

When I found out it wasn't, I was immediately hooked.

(I think it was mostly because of the ⎕s.)

Fawn Locke

Oh, I see. Learning tacit is unfortunate, you can't use it casually because you do not understand it, and you don't understand it because you can't use it, once you get over the initial curve the growth of learning becomes exponential

rabbitgrowth

Think that's true of many other things too.

Fawn Locke

Yeah, I think this is APL's only feature that's like that though

rabbitgrowth

8:17 AM

It felt like a bunch of arbitrary rules at first, and seeing examples like 5(+,-)2 in the APL Wiki helped - you can read it as "plus and minus". That answered the "why" for me.

I should add that ]box on -trains=tree has been extremely helpful. Also it looks pretty ;)

Fawn Locke

Yeah, I like tacit because it expresses some ideas very naturally. And reveals patterns in your code

rabbitgrowth

I don't think I would otherwise have thought of programming as building a tree of functions. It really is beautiful.

Richard

8:51 AM

@ZtA0 using )COPY you can append two workspaces. Or maybe I misunderstood your question

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