The Nineteenth Byte

Mayube

3:00 PM

oh. ohhhh

ais523's temporary account

…and that comes out as just 13 bytes, I should have tried it first

Mayube

jeez I'm spending 12 bytes just producing ~(b)(a)

ais523's temporary account

so am I

Mayube

OH

:)

I ran it and it just output a and then it took me a second to realise what had happened

ais523's temporary account

I think that applying the techniques in these two CMCs is sufficient to produce pretty much all my Underload answers at CGCC, normally I try to solve a problem with just those, and if I can't, I don't bother

but, there is more to the language

UMC: add two numbers (in Underload, taken as Church numerals from the stack). (Side note: there isn't an Underload answer to the main-site version of the question yet, so feel free to post your answer once you have it.)

0

A: New users' guides to golfing rules in specific languages

Underload Underload is a stack-based tarpit esolang, which can be a good choice for some problems (especially quines) and a horrible choice for most of the others (but even horrible choices can be fun to golf in!). If you're planning to use it at CGCC, here's what you need to know: The basics CGC...

Mayube

3:09 PM

why is 0 !() and not just !?

ais523's temporary account

because you're replacing a string with n copies of itself

e.g. 4 maps "a" to "aaaa"

so 0 must map "a" to ""

and so you have to push the empty string onto the stack after deleting the string that was there beforehand

Mayube

ah so it has to push an empty value, got it

ais523's temporary account

hmm, the main-site "add two numbers" question requires handling negative numbers, probably that's why there are no Underload answers (because there's no standard way to represent them, that's consistent with the positive numbers in how they react to arithmetic)

Mayube

I'm trying to figure out an underload truth machine. It's deceptively complex

Somewhat ironically the Extended truth machine seems to be much easier in underload than the standard one

ah no, it requires handling negative numbers

and the standard truth machine only allows unary output if the language is incapable of outputting 0 or 1 :(

ais523's temporary account

3:33 PM

I think the trick is to write a program that outputs 0 and exits, and a program that outputs 1 in a loop, and just use the input to choose between them

Mayube

((:(1)S^):^)((0)S)(~)(input)^^^ should do it I think, but it might be golfable

ais523's temporary account

that seems about right; I think it's golfable though

you don't need to use the ~ – you can run the infinite loop of 1s a number of times equal to the input, then print 0 and exit

Mayube

25 bytes: Try it online!

Correction: 24 bytes: Try it online!

ais523's temporary account

it looks like I posted an Underload truth-machine to the main site; advertised as "16 bytes" but I forgot the parens around the outside (as usual) so it's actually 18

when testing my own CMCs I often forgot the parens and wondered why the interpreter was segfaulting

(actually, I don't get why TIO's interpreter segfaults on stack underflow rather than having error handling…)