The Nineteenth Byte

Doorknob

02:00

For extremely narrow definitions of "learn"

A Nerd - I

^

Downgoat

Is there a faster way to parse a grammar rather than attempting all the things?

Maltysen

@Downgoat probably

Downgoat

pls tell

Maltysen

@Downgoat idk how to, but there usually is a better way than doing all the things

Downgoat

02:03

probably not in grammars

e.g. If I have the grammar:

E -> α β
     ε
α -> ( E )
     L
     B
     P
     O E
β -> O E?
     ε

how would ii optimze

aditsu

depends what type of grammar

Downgoat

@aditsu CFG

aditsu

Top-down parsing

In computer science, top-down parsing is a parsing strategy where one first looks at the highest level of the parse tree and works down the parse tree by using the rewriting rules of a formal grammar. LL parsers are a type of parser that uses a top-down parsing strategy. Top-down parsing is a strategy of analyzing unknown data relationships by hypothesizing general parse tree structures and then considering whether the known fundamental structures are compatible with the hypothesis. It occurs in the analysis of both natural languages and computer languages. Top-down parsing can be viewed as an...

PhiNotPi

I came across an interesting "number puzzle" on social media.

Downgoat

@aditsu that is what I'm using

PhiNotPi

02:08

1 + 4 = 5
2 + 5 = 12
3 + 6 = 21
8 + 11 = ?

Downgoat

it basically tries all the things

quartata

ugh pepper download faster I don't have all day

Downgoat

@PhiNotPi uh, 96?

A Nerd - I

^

PhiNotPi

Yes, but why that and not some other number? My first thought was "obviously there's infinitely many solutions"

Downgoat

02:10

1 + 4 = 1 + 4(1) = 5
2 + 5 = 2 + 5(2) = 12
3 + 6 = 3 + 6(3) = 21

A Nerd - I

@PhiNotPi Method of finite differences

Downgoat

seems to work for most things

PhiNotPi

So, I went and tried to find other solutions of the form ax^2 + bxy + cy^2 + dx + ey + f

A Nerd - I

f(x+1,y+1) = f(x,y) + (x+1) + (y+1)

PhiNotPi

And, it turns out, regardless of what values of a,b,c,d,e,f I chose, that the answer was always 96.

aditsu

02:12

@Downgoat not sure what you mean by that, and it's been a long time since I did something like that, but I think there's a form of DP you can use

Downgoat

Also, does anyone see how this grammar could possibly enter an infinite loop?:

E -> α β
     ε
α -> ( E )
     L
     B
     P
     O E
β -> O E?
     ε

aditsu

E -> α… -> ( E ) … -> ( α… ) …

Downgoat

@aditsu ಠ_ಠ

@aditsu but that's finite

there's no left recursion

PhiNotPi

What happens is that, since the sample points are linearly dependent (the second number is always 3+first number), the ax^2 + bxy + cy^2 + dx + ey + f polynomial simplifies down to gx^2 + hx + i, in which there's only three unknowns.

aditsu

it's infinite

no left recursion indeed

PhiNotPi

02:16

This means that, even though there's lots of solutions (x(1+y), or x(4+x), etc.) that produce different values for untested points, all of those solutions produce the same value for (8,11)

Downgoat

@aditsu oh

shit

any idea on how to fix

aditsu

you want it to be left-recursive?

Downgoat

no, wait

no that won't cause inifnite recursion

aditsu

then what do you want to fix?

Downgoat

what would be the input which would cause infinite recursion?

aditsu

02:18

it would be an infinite input

Downgoat

wat

PhiNotPi

So, I brought up that number puzzle because I thought it was interesting that, if not for the fact that the two inputs were linearly dependent, then there would be an infinite number of solutions (limiting ourselves to quadratic polynomials).

aditsu

lim(n->∞) ("("*n ")"*n)

Cᴏɴᴏʀ O'Bʀɪᴇɴ

100 bytes, 8 languages!

PhiNotPi

If the last line were instead 8 + 12 = ? then it would be unsolvable.

A Nerd - I

02:22

@PhiNotPi Isn't it, since there are three points, if the polynomial is f(n,n+3) = an^2+bn+c, there is only one solution?

Specifically, f(n,n+3)=n^2+4n

PhiNotPi

Or, I should of said, one was a linear function of the other.

A Nerd - I

@QPaysTaxes You can't define a quadratic from two points; you need at least 3

Given f(a,b), what is the relationship between a and b here? Is b a linear transform of a?

quartata

Every tutorial I've found for Pepper is in C++ :(

PhiNotPi

What's the more accurate term for... b is a linear polynomial of a?

as in, it can have a constant term, which it does here.

A Nerd - I

@PhiNotPi If b = ma + n, then b is a linear transform of a.

PhiNotPi

02:26

Okay, then that's what I meant.

A Nerd - I

Which we can determine, since we're given ≥2 points on the line

PhiNotPi

I don't really have much more of a point to make, I was just trying to say "this is interesting, turns out the puzzle is only "solvable" because one input is a linear transform of the other"

A Nerd - I

Oh, ok. Lol

PhiNotPi

@ANerd-I It would also be funny if this were Python that lost its tabbing.

Cᴏɴᴏʀ O'Bʀɪᴇɴ

which languages use # as a comment?

PhiNotPi

02:32

Perl

Maltysen

python

A Nerd - I

Python

Maltysen

coffeescript

A Nerd - I

ugh

Ninja'd

PhiNotPi

sumo'd

Doorknob

02:32

ruby

bash

Downgoat

@CᴏɴᴏʀO'Bʀɪᴇɴ cheddar

PhiNotPi

Java if you squint really hard.

Cᴏɴᴏʀ O'Bʀɪᴇɴ

Thanks guys. Am working on a polyglot

Downgoat

bash

quartata

Even Google's examples are all in C++ even though I know Pepper has a C API

This is kinda annoying

Cᴏɴᴏʀ O'Bʀɪᴇɴ

02:34

@Downgoat how do you output in cheddar?

Downgoat

@CᴏɴᴏʀO'Bʀɪᴇɴ print

quartata

@CᴏɴᴏʀO'Bʀɪᴇɴ print(

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@Downgoat :D

Downgoat

but currently only numbers are supported

Cᴏɴᴏʀ O'Bʀɪᴇɴ

-int(-15/2) <-- what does that eval to in Cheddar?

Downgoat

02:35

so like print 2+2 would work but print "foo" + "bar"

@CᴏɴᴏʀO'Bʀɪᴇɴ lemme run it through the call stack gen

PhiNotPi

You should use my language Element, it is really great and does all things.

Downgoat

@CᴏɴᴏʀO'Bʀɪᴇɴ RunTime error as there is no int function

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@PhiNotPi Does it have comments?

RenderSettings

[citation needed]

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@Downgoat aw :(

A Nerd - I

02:36

You should use my language Arcturus, it <starts crying>

PhiNotPi

Comments in the form of "pushing a string on the stack and then deleting it"

Downgoat

@ANerd-I -1 for using - and not — or –

A Nerd - I

@Downgoat ok

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@PhiNotPi how to write a string?

A Nerd - I

What languages use % as a comment?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

02:37

or docs

Downgoat

@ANerd-I postscript

PhiNotPi

Also, I totally missed what challenge this is for.

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@ANerd-I brainfuck

@PhiNotPi Noncompeting entry to versatile integer printer

Downgoat

is HTML considered a programming language?

A Nerd - I

@CᴏɴᴏʀO'Bʀɪᴇɴ Isn't everything except the eight specific characters a comment?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

02:38

@ANerd-I that's the point ;)

A Nerd - I

<eyes>

PhiNotPi

@CᴏɴᴏʀO'Bʀɪᴇɴ docs are here

Make a string by literally having the string literal in the code.

Cᴏɴᴏʀ O'Bʀɪᴇɴ

So, like "asdf"?

PhiNotPi

Output is the ` character.

asdf

^ like that

Maltysen

@PhiNotPi what about phi's golfo supreme?

PhiNotPi

02:40

Not enough functionality at the moment.

Cᴏɴᴏʀ O'Bʀɪᴇɴ

#El+"1"''(++)--[-[--<]>>--]<++++.j15+x#x
#~o+4                               ;n6<
print(-int(-15/2))

8 langs so far

Downgoat

nice

Cᴏɴᴏʀ O'Bʀɪᴇɴ

See how many you can guess.

Maltysen

bf, python

Cᴏɴᴏʀ O'Bʀɪᴇɴ

version of python?

PhiNotPi

02:41

The program asdf`outputs the string asdf

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@PhiNotPi oo that's helpful. what's terminate the program?

Maltysen

@CᴏɴᴏʀO'Bʀɪᴇɴ both?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@Maltysen yes

@QPaysTaxes yes

4 / 8

Maltysen

@CᴏɴᴏʀO'Bʀɪᴇɴ lua?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@QPaysTaxes yes

@Maltysen nope

A Nerd - I

02:42

<>< ?

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@ANerd-I yes

The rest you don't know

^ nj

brainbash, reng are the other two

PhiNotPi

Well, the stuff beforehand is executed, but the results are never used, and the stuff afterwards is also not used (as long as you don't have another ` in a place that randomly causes it to print stuff)

Cᴏɴᴏʀ O'Bʀɪᴇɴ

@PhiNotPi So, 9` would print 9 and effectively do nothing else?

PhiNotPi

The only real concern is balancing brackets.

@CᴏɴᴏʀO'Bʀɪᴇɴ yes

Cᴏɴᴏʀ O'Bʀɪᴇɴ

What marks the start of the string?

oh

PhiNotPi

02:44

Either whitespace or a non-alphanumeric character.

Cᴏɴᴏʀ O'Bʀɪᴇɴ

interpreter?

PhiNotPi

element.tryitonline.net

RenderSettings

@Downgoat i actually saw a thing about HTML + CSS being Turing complete, as long as you have a person holding down the spacebar. Simulating some cellular automaton and leveraging the browser's element switching code to treat visible/nonvisible element differently.

aditsu

@Downgoat you might be interested in en.wikipedia.org/wiki/CYK_algorithm

Cᴏɴᴏʀ O'Bʀɪᴇɴ

why doesn't this work Phi?

@QPaysTaxes Get to work. Write the number 9 every time I want you to.

RenderSettings

02:46

stackoverflow.com/questions/2497146/is-css-turing-complete there we go, that one links to it

Cᴏɴᴏʀ O'Bʀɪᴇɴ

:P

I gotta go.

Downgoat

@RenderSettings bu can it due primaiialiality checking is the questoin

RenderSettings

@Downgoat It's Turing complete. So yes.

Downgoat

please giv sampl coed

RenderSettings

@Downgoat I, uh, really don't want to have to try and put together a primality check simulation in Rule 110 :p

Downgoat

02:49

i will giv you a +.500 bounty if you do

PhiNotPi

@CᴏɴᴏʀO'Bʀɪᴇɴ So... I think something up in the first line isn't happy with whatever arguments it received (run-time error or something)

element.tryitonline.net/…

^^ any further back in the source seems to cause an error.

So... IDK if you're going to be able to get it to work, sorry.

aditsu

many Turing completeness proofs seem to go like "if you write these 20000 lines of code, it can simulate rule 34 110, which can simulate brainfuck, which can implement SKI calculus, which is proven in this 500-page book to be Turing complete"

Downgoat

@Dennis what process must a language go through to be put to TIO?

PhiNotPi

I'm getting a bunch of soundcloud spammers liking/following me.

RenderSettings

@aditsu god this is actually completely accurate for Rule 110. it's like 4 layers of indirection to get a Turing machine, which is "will output a bit sequence xxxx iff the program halts"

/me glosses over the paper on compiling a Turing machine to Rule 110
This is not worth +500

El'endia Starman

03:05

Man, Bicentennial Man is such a good movie...

RenderSettings

Becomes human again and lives happily ever after?

quartata

Dammit, I just realized I'm probably gonna need to write my own module loader.

rip in perl quartata, killed by perlxs

El'endia Starman

03:26

@QPaysTaxes Not the same, then.

@QPaysTaxes Oh, so it was the basis. In the movie, though, the robot is eventually declared human after all of his internal wiring and mechanisms were replaced with human organs.

Right.

Oh, I see, right.

Just read the plot summary on Wikipedia, and the story isn't quite the same. There are a lot of similarities though, especially the first part (before he gets his freedom).

@QPaysTaxes Hah, true.

Dennis

03:47

@Downgoat Step 1. Tell me which language. Step 2. Wait until I add it to TIO.

aditsu

04:00

8 bytes! \:D/

welp, that didn't last long :/ "Jelly, 3 bytes" - although that might not be correct, but it probably will take at most 1 byte to fix it

2

A: What's the missing column/row? (GCJ 2016-1A rankfile)

CJam, 8 - 10% = 7.2 With modified input/output formats, this works: Lq~]:^$p Try it online And here is the code I actually submitted at GCJ (24 bytes): li2*({l~}*]$e`{(2%*~}%S* Try it online Explanation: This basically lists the values that appear an odd number of times. L push an ...

Dennis

@aditsu I just noticed the input format. That's not going to be pretty.

aditsu

@Dennis "or modify the input format as you like"

Dennis

Oh! Then all I have to do is sort, I think.

aditsu

probably

looks like we got the "^" idea simultaneously

Dennis

@aditsu That's actually what I did in Code Jam.

e# The CJam interpreter is available at sourceforge.net/projects/cjam

li{"Case #"V):V": "]o

li2*({[l~]}*]:^$S*

N]o}*

aditsu

04:07

oh I didn't know that, I just figured it out a few minutes ago

hmm, array of arrays, that makes it easier (as in shorter)

xnor

there's been a lot of challenges lately that come down to a mathematical trick

not sure how i feel about them

aditsu

6 bytes ^_^ (still editing)

@Dennis you can claim the 10% bonus

Dennis

Probably. Jelly is slow, but I don't think it's that slow.

aditsu

@QPaysTaxes and three is 5 bytes

Maltysen

@aditsu I would have 3 bytes in pyth if we had a symetric difference

Dennis

04:16

@Maltysen I would have zero bytes if Jelly did this by default...

Maltysen

@Dennis hahaha

aditsu

I still think everything should be counted in UTF-8

always

Maltysen

that's actually a really good idea

R. Kap

How about ascii?

That is what we actually type in (usually), and therefore, it should be counted in that.

aditsu

@R.Kap that was my original idea, but that disqualifies APL so it's too contentious

Maltysen

04:19

@R.Kap ascii doesn't allow all the characters, only the first 128 code points

also, ascii is the same as UTF-8 for the code-points it works for

New Main Posts

0

Q: Which switches are on?

Introduction Given an input of a block of string containing 1 or more of each character in !@#$^&*, output the coordinates of the switch(es) that is/are "on". A switch is a $, and a switch is "on" if and only if it satisfies at least 1 of the following criteria: It is surrounded by all ^. S...

Dennis

@aditsu That assumes all submissions are character-based, which isn't true.

El'endia Starman

Are there any text encodings that aren't ASCII for the printable ASCII characters?

aditsu

UTF-16

Dennis

EBCDIC

And pretty much everything that came before ASCII.

El'endia Starman

04:21

@Dennis Well, that's basically a given.

aditsu

@Dennis all source code should be character-based

Maltysen

@QPaysTaxes unicode is a list of code points

utf-8 is the usual encoding, but there are others, like the custom one jelly uses

aditsu

@QPaysTaxes no, an encoding is a mapping between code points and series of bytes

well, IMO, UTF8 is the encoding for Unicode :)

R. Kap

You know, I really must know, in Python, does chr() convert to utf-8 or asc-ii?

Dennis

@aditsu We get quite a few submissions on a regular bases that aren't (TI-BASIC, machine code, Piet, etc.).

@R.Kap That depends on your locale.

aditsu

04:25

heh, "asc-ii"

Sp3000

Also depends on which Python

New Sandboxed Posts

0

A: Sandbox for Proposed Challenges

Which switches are on? code-golfstring Introduction Given an input of a block of string containing 1 or more of each character in !@#$^&*, output the coordinates of the switch(es) that is/are "on". A switch is a $, and a switch is "on" if and only if it satisfies at least 1 of the following ...

aditsu

@Dennis machine code is not source code, Piet -> ASCII ppm, as for TI-BASIC, I say count the characters :p

R. Kap

@Dennis Locale?...

Dennis

@aditsu You can save a byte by turning your program into a function.

Locale

In computing, a locale is a set of parameters that defines the user's language, region and any special variant preferences that the user wants to see in their user interface. Usually a locale identifier consists of at least a language identifier and a region identifier. On POSIX platforms such as Unix, Linux and others, locale identifiers are defined by ISO 15897, which is similar to the BCP 47 definition of language tags, but the locale variant modifier is defined differently, and the character set is included as a part of the identifier. It is defined in this format: [language[_territory][.codeset...

Rainbolt

04:32

@Geobits Yep, that was me. When I rain I pour.

Alex A.

obligatory ( ͡° ͜ʖ ͡°)

Rainbolt

I waved at your kid as I was splattering on your windshield.

Alex A.

uh... ._.

aditsu

oh jizz

@Dennis I think that's kind of a stretch… but maybe acceptable

Geobits

@Rainbolt I'll make sure to let him know.

Alex A.

04:41

@aditsu >:/

aditsu

@Dennis looks like some odd smiley {:^$}

El'endia Starman

04:56

Is it always possible to match a grammar specification with a language written in that grammar, or is that never possible?

Alex A.

I don't see why that wouldn't be possible

aditsu

what do you mean by matching them?

El'endia Starman

Like, from a grammar specification, create a parser that will correctly parse that grammar to create a parser that etc... Kinda like a quine.

aditsu

well, you can create a parser for a grammar, not sure about the 2nd "to create a parser" part

Alex A.

If I'm not mistaken, that wouldn't be too different from a language parsing itself, right?

El'endia Starman

05:05

Yeah, I guess that's basically it.

phase

3

Alex A.

@phase That's amusingly relevant to jQueryOS or AvocadOS or whatever they decided to call it

phase

@AlexA. why I just made it and posted it in this chat

Alex A.

Oh I didn't realize you made it

phase

@AlexA. toollll

Alex A.

05:10

This is amazing

phase

Kids, there’s nothing cooler than having a clean desktop. #SonicSez https://t.co/NtqKB1jGLS

Tweeted by sonic_hedgehog on April 8, 2016 at 5:16 PM

Maltysen

@phase ~~how did you know what I'm doing right now?~~ I mean, who does that?

(jk, I use gcp anyways)

phase

Alex A.

@phase what

aditsu

phase

05:17

aditsu

a soya programmer ^

Alex A.

@aditsu lol @ author Bill O'Reilly

@Maltysen Is that drugs?!

Maltysen

@AlexA. google cloud platform - not even once

aditsu

6

Alex A.

XD

El'endia Starman

05:25

> Easy as magpie

Excellent.

Maltysen

@QPaysTaxes a few ways, depends on the situation

is it a for loop?

where do you want to break?

so you can nest inside a function and return, but I think a for else: might be better

^^ oh for-else is perfect

for literal in literal_types:
	if condition:
		break
else:
	continue

El'endia Starman

python-notes.curiousefficiency.org/en/latest/python_concepts/…

For what it's worth, this is the first time I'm reading anything about for-else. :P

Maltysen

that doens't exactly work, but you get the idea

El'endia Starman

I think I only even heard of it days or weeks ago.

Maltysen

they also work on while loops

one of python's coolest features imo

Alex A.

05:41

@Maltysen -1 billion for using tabs

Maltysen

yeah that code up there might not be exactly correct

@AlexA. fricken text boxes online

actually, brb copy-pasting tabs

damn it, its been 2 minutes

El'endia Starman

Tabs do show up in code blocks here. They just render as 8 spaces.

Alex A.

@Maltysen >:D

Dennis

@Maltysen fixed

@AlexA. eleven

Alex A.

D:<

Maltysen

05:50

@Dennis \o/

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