So much satisfaction when I finally beat Dennis's golflang submission...

@Bubbler that residue-pseudoscan is clever. can i steal your algorithm and rewrite it in k?

@ngn Sure, no problem

@Bubbler it turned out shorter!

apl is usually 25% shorter than k, "extended" even more

@ngn Well, J can win over APL too...

@Bubbler 18 bytes in k

@Bubbler i don't know much "extended" but wouldn't it be simpler to decode the inputs with something like {+/fibs[⍸⌽⊤⍵]}? you already have code to compute the fibs

@ngn Yeah, that works

but it's still 47 bytes, slightly longer than your K

@Bubbler another idea (i think this will work) - take the two inputs as a single argument

or as a single ⎕

tio (rm the { } and replace last ⍵ with ⎕)

@Bubbler also: 1↓(1,+\⍤,)⍣20⍨1 -> (2+/,)⍣38⍨0 1 or (2+/,)⍣38⍨⍳2 with ⎕io←0

(the sequence loses precision near the end)

Wow.

@ngn That, combined with taking a single 2-element array, gives 41 bytes

40

Doesn't a full program need ⎕← for output?

Adam's recent solutions don't use it, so I guess it's fine

@Bubbler similar discussion here

the program being f←'AB' 'AB' 'ACD' 'ACE'⌷⍨∘2⊥

@JoKing It's a 3-train. 1) 'AB' 'AB' 'ACD' 'ACE' 2) ⌷⍨∘2 3) ⊥

The most important thing is that the thing at position 2) is always dyadically called, regardless of how you call the function f.

And the uptack at 3) is dyadic only

But you did bind one side of 2) using ∘2 so it can't be called dyadically, thus the error

I think both error messages refer to a different the function

The first one being ⊥, and the second being ⌷⍨∘2

@H.PWiz Right.

@JoKing Perhaps you wanted ⌷⍨2∘⊥?

@Bubbler With ⎕fr←1287, 1∧+∘÷\38/1 would be a shorter fibonacci generator. I'm assuming you want that many terms. (otherwise ⎕fr might not be necessary)

@Bubbler Oh okay, I think I need a bit more practice with trains... and with the ⍨ operator

i'm still not quite sure why the ∘ should be after the 2 rather than before?

ohh, i didn't realise there were multiple forms of composing

@user1900396 Hey there. Nice to have you stop by!