The Nineteenth Byte

Manish Kundu

18:00

P

:P

Mr. Xcoder

We've just been taught what a function is, what a graph of a function means, linear functions and order 1 functions, so not much.

Separately, I have studied derivatives (now studying all their rules), a tiny bit of integration, restrictions and properties of functions

Manish Kundu

The worst part in calculus is when they ask you to find the limits but without using L Hopitals

Mr. Xcoder

The worst part in calculus is when they ask you to approximate definite integrals using Riemann sums :p

ETHproductions

Ah yes, going through that right now myself

Mr. Xcoder

@ETHproductions Oh god good luck!

ETHproductions

18:04

So far it's really just been "and so we approximate like so, and when we take the limit as n->inf we end up with this integral"

I hope there's no quizzes where we actually have to calculate the approximate Riemann sum itself :P

Mr. Xcoder

I find integration quite hard compared to differentiation

DJMcMayhem

Same

Mr. Xcoder

^^^ Good lord, that would be so imprecise :P

DJMcMayhem

Differentiation is waaaay easier

Mr. Xcoder

I really need a professor to get into integration properly, can't do it by myself. I guess I'll wait for 4 more years until the 12th grade :P

ETHproductions

18:06

Yeah, chain rule >>> substitution rule

Mr. Xcoder

Agreed.

ETHproductions

The method my prof used to find the antiderivate of sec(x) was so out-of-the-way I would have never found it

Mr. Xcoder

Although some mathematicians think differentiation is mechanical

Neil

@DJMcMayhem interestingly the differential of tan is slightly less undefined than tan is, since it only diverges to +Infinity whereas tan diverges to either +Infinity or -Infinity depending on which direction you approach the discontinuity

Mr. Xcoder

@ETHproductions Lol, I've just encountered that earlier

ETHproductions

18:10

@Mr.Xcoder I agree, to differentiate you can just apply a certain set of rules. With the substitution rule you have to actively find a way to break up the function into smaller pieces

hmm, are there functions that don't have antiderivatives?

DJMcMayhem

@Neil Huh. That's fascinating

CMC: What PPCG challenge has the most other challenges closed as a duplicate of it?

ETHproductions

The original KC challenge

Mr. Xcoder

Oh misunderstood

Rickroll definitely

@ETHproductions There are some that don't have elementary antiderivatives.

(The only answer is amazing, not that I understand all of it)

ETHproductions

wow, that'll be quite a read

there are 10 dupes of that challenge

Mr. Xcoder

Just 10 o.o

ETHproductions

18:16

non-deleted anyway

J. Sallé

@Mr.Xcoder the top comment on the answer is the best

> Raymond, I don't believe you've given enough detail.

Mr. Xcoder

And it's a community wiki! ಠ_ಠ

Erik the Outgolfer

wow that's like 13.6 pages or something

totallyhuman

hi

Mr. Xcoder

\o

Conor O'Brien

18:29

CMC write a function that returns itself

Erik the Outgolfer

@ConorO'Brien Python 2, 10 bytes

f=lambda:f

DJMcMayhem

Dang

I had def f():global f;return f

Erik the Outgolfer

... what?

DJMcMayhem

I didn't think about lambdas lol

Erik the Outgolfer

dang markdown you have disappointed me

totallyhuman

18:32

@ConorO'Brien Haskell, 3 bytes: f=f

hehe

Anonymous

@totallyhuman Haskell (Lambdabot), 3 bytes: fix

Anonymous

Probably cheating :P

Mr. Xcoder

@ConorO'Brien JS (untested): f=()=>f

NieDzejkob

@Mr.Xcoder -1 byte: f=a=>f

totallyhuman

@Mr.Xcoder f=_=>f

Mr. Xcoder

18:35

@NieDzejkob Is that allowed?

totallyhuman

ninja'd 'cause lag >_>

@Mr.Xcoder javascript doesn't care about what arguments are passed

Mr. Xcoder

Ok then

Anonymous

In JS, arguments are more like suggestions

totallyhuman

also that'd be valid anyways 'cause unused input is allowed

Mr. Xcoder

Solution: Don’t use JS.

Potato44

18:36

@totallyhuman I don't think that counts, I believe that is an infinite loop

totallyhuman

yes but it does return itself :P

it returns itself which returns itself which returns itself...

ETHproductions

@ConorO'Brien Japt, 3 bytes: =@U

J. Sallé

@ConorO'Brien APL (Dyalog Unicode), 1 byte +

totallyhuman

@J.Sallé huh, then Haskell, 2 bytes: id

ETHproductions

I think that would allow the 4-byte JS solution eval, or atob, btoa, etc.

or am I misunderstanding how that works?

Anonymous

18:41

@ETHproductions How does eval return itself?

totallyhuman

no as eval() doesn't return eval

ETHproductions

calling id in Haskell returns id? That's interesting

totallyhuman

uh well

not quite

J. Sallé

@ETHproductions Dyalog APL returns whatever function you type if it doesn't have arguments, as I see it at least. Probably @Adám can explain better.

AdmBorkBork

@ConorO'Brien PowerShell, 7 bytes -- $a={$a}

ETHproductions

18:43

@J.Sallé oh, I see the difference. Seems kinda cheaty though

totallyhuman

it's the way functional languages work :P

MD XF

@ConorO'Brien C, 11 bytes: x;f(){x=f;} Try it online!

J. Sallé

@ETHproductions I assume it is kinda cheaty, I just answered because it was a CMC :p

Anonymous

@MDXF -1: f(x){x=f;}

MD XF

:o

Conor O'Brien

19:02

@Mego so long as calling fix with no arguments returns fix it should be fine

@MDXF well, if the function really returns itself, then f()() == f, but this is not the case, as your function returns a memory location

Anonymous

Technically calling any function with no args in Haskell returns itself :P

Anonymous

So ap would be shorter in Lambdabot Haskell :P

H.PWiz

Or just id

Conor O'Brien

the thing is, the function has to be called :P so afaict, since APL doesn't evaluate its functions when presented with no arguments, it does not count.

@Mego looking into it, functions in haskell can't be called without arguments, right?

RosLuP

In C would be char*f(){return f;}

In Apl one function that return itself would be {∇} but for me not compile...

Anonymous

19:10

@ConorO'Brien Sure they can. It's entirely possible to define nullary functions: a=1.

RosLuP

In Axiom f(x)==(...;f)

Conor O'Brien

@Mego ok, they can be defined, how might you call one tho?

Anonymous

@ConorO'Brien Just like any other function?

Anonymous

tio.run/##y0gszk7Nyfn/P9HWkCs3MTPPtqAoM69EIfH/fwA

Conor O'Brien

I don't know haskell, but I'm interested in testing the fix solution. how might I verify it?

Mr. Xcoder

19:14

Totally unrelated, but dimensional analysis is a life-saver!

Anonymous

@ConorO'Brien I realized after I posted it that it doesn't work unless you call it with itself as an argument :P

Conor O'Brien

oh lol

Anonymous

Unless you look at it from the perspective of "every function returns itself with 0 arguments"

Conor O'Brien

hm, this calls for another cmc

Anonymous

In which case there are shorter solutions, like id or 1

Conor O'Brien

19:16

CMC: write a function that returns any other function that isn't itself

that looks good I think?

Anonymous

Well it depends on how you define "other function"

Anonymous

With f=id, f and id are functionally identical, but have different names

Conor O'Brien

well, f() != f && f is a function

DJMcMayhem

@ConorO'Brien Python, 15 bytes: lambda:lambda:1

Anonymous

@DJMcMayhem Why not just lambda:id?

DJMcMayhem

19:21

Because I have a nasty golf habit where I implement the first thing I can think of and then post it without thinking of shorter alternatives

Anonymous

me too thanks

Conor O'Brien

nonetheless the lamba lambda is kinda cool :>

Anonymous

Actually: ⌠`1⌡

Anonymous

(which is just lambda:lambda:1)

DJMcMayhem

@Mego Technically you could even do something like str.find

I'm not sure what the shortest class.method combo is though

Anonymous

19:23

I should make Actually's parsing better so that can be written as ``1

AdmBorkBork

lambda lambda red pajambda

MD XF

19:41

@ConorO'Brien wrong

f()() is just not valid syntax

Adám

@ConorO'Brien Non-cheating APL (Dyalog Unicode), 9 bytes Try It Online!:

r←f x
r←f

It takes a dummy argument, actually runs, and actually returns itself (which can then be applied to some other (dummy) argument.

@RosLuP Dfns cannot return functions as a result.

MD XF

@ConorO'Brien or to more clearly disprove that

I had to refer to this that I wrote when I was 13 (and put on GitHub years later) to write that

Adám

@ConorO'Brien Sorry, this is an example run.

Anonymous

@MDXF You didn't free that memory. Shame on you.

Adám

@ConorO'Brien APL (Dyalog Unicode), 9 bytes Try It Online! (non-cheating, takes dummy arg, returns plus)

MD XF

19:47

@Mego You're referring to basics.c? No memory is allocated

...except for foo

Anonymous

Exactly

MD XF

Fixed

Anonymous

@MDXF I think with enough parens in the right places (plus a cast), you can make f()() work, but I don't want to try right now

MD XF

@Mego I'm pretty sure it's completely impossible but I'd love to see it if you do figure it out

Conor O'Brien

@MDXF oh, right, I was thinking you couldn't cast functions for some reason

MD XF

20:03

Anyone know why this happens?

mudkip201

@ConorO'Brien Pyt 5 bytes: 2⁶Đ⁺ṕ

MD XF

@mudkip201 just curious, do you know about Cubically?

Anonymous

@MDXF Change line 47 to char *tmp = malloc(strlen(s) + strlen(lastbrace.since) + 1);

mudkip201

@MDXF haven't really looked into it

MD XF

@mudkip201 just wondering because your first few dozen codepage values are the same as Cubically's

mudkip201

20:16

Huh. Strange

but completely coincidental

MD XF

Interesting

(no accusations here I'm just legitimately interested)

@Mego ლ(ಠ益ಠ)ლ

caird coinheringaahing

@mudkip201 How many characters are in the Pyt code page?

mudkip201

currently 200

caird coinheringaahing

And almost none are ASCII? :P

mudkip201

intentionally

allows for comments

since there isn't a comment character

Anonymous

20:21

@MDXF Gotta remember that null terminator :P

caird coinheringaahing

@mudkip201 You could just not have comments.

mudkip201

@cairdcoinheringaahing Eh. Not changing it now :P

caird coinheringaahing

I quite like Jelly's way of having comments: ḷ“comment” It works because ḷ only takes the left value and ignores the string to its right :P

ETHproductions

but then you can't include ” in your comments /s

MD XF

@Mego hm how about this (if you immediately spot any problems, don't waste too much of your time)

DJMcMayhem

20:24

@cairdcoinheringaahing So then what's the point of ḷ?

Is there somewhere it's actually useful?

caird coinheringaahing

Getting the first value of a list, without modifying the list: ḷ/

DJMcMayhem

:O

I have always wanted to do that

Erik the Outgolfer

(with error instead of 0 on empty list :D)

caird coinheringaahing

Also, to get the last value, you can use ṛ/ and to make all values in a list equal to the first, you can use ḷ\

Erik the Outgolfer

also: ḷ"

Adám

20:32

@cairdcoinheringaahing Comes from APL ⊣'comment'. Together with ⊢ it allows you to insert comments inside expressions, e.g. 'two'⊢2*⊢'power'⊢'three'⊢3⊣'evaluate' gives 8.

Anonymous

@MDXF Use strncpy - orig may not have a null terminator

Adám

@DJMcMayhem In APL, on a matrix, ⊣/ is the leftmost column, ⊢/ the rightmost, ⊣⌿ the top row, ⊢⌿ the bottom row.`

Anonymous

Or explicitly add a null terminator to orig

MD XF

@Mego Ahh, I was passing a string without a null terminator. That wasn't the problem tho

Anonymous

Also valgrind is your friend

Anonymous

20:35

The problem is that strcpy reads the src string up to a null terminator. If there isn't one, it keeps reading past the allocated memory.

Erik the Outgolfer

@Adám uh, APL already has ⍝comment :P

Adám

@EriktheOutgolfer Yes, but it doesn't allow you to comment ⋄ separated expressions or include comments inside trains or one-liner dfns: avg←('sum'⊢+/)('divided by'⊢÷)('count'⊢≢)

Erik the Outgolfer

@Adám why would you want to do that >_>

of course you can do this in Python too

lambda x, y:'Addition' and x + y

caird coinheringaahing

Assuming that x + y != 0

Erik the Outgolfer

why

Adám

20:41

@EriktheOutgolfer ¯\_(⍨)_/¯

caird coinheringaahing

@EriktheOutgolfer Nevermind, I forgot how and works

Adám

@EriktheOutgolfer What does that mean?

Erik the Outgolfer

well, lambda x, y: is the "header" of an anonymous function (pretty much like Dyalog's {} but also specifying the arguments' names and other properties), in this case with two arguments x and y

'Addition' is simply the string Addition

and is the logical AND operator

Adám

@EriktheOutgolfer OK, I understood all of that, but how does and do ⊢ ?

Erik the Outgolfer

since it determines 'Addition' is truthy (non-empty for strings), it returns its right argument, x + y

@Adám ^ (it's a bit hacky)

Adám

20:44

@EriktheOutgolfer Yikes!

caird coinheringaahing

@Adám a and b returns b if a is truthy else a :/

Adám

@cairdcoinheringaahing Ugh.

trichoplax

For a language designed to encourage readability, Python is surprisingly easy to be hacky in

Erik the Outgolfer

@Adám well, Python's logic isn't that "0 is falsy, 1 is truthy, don't dare bother me with other values" ;)

caird coinheringaahing

Ironically, it's only unreadable when it's intended to be written, rather than read. Most pieces of Python code are fairly easy to understand what they do, when not golfed :P

Anonymous

20:47

An advantage of a and b over the more-readable a if a else b is that b isn't evaluated if a is truthy

Erik the Outgolfer

uh, it's not?

I don't think the latter unnecessarily evaluates b either

the advantage is that you only write a once :P

Adám

Hm, I'm quite content with APL's "1 is truthy, 0 is falsy, everything else is not Boolean".

Erik the Outgolfer

and a (dis?)advantage is that and has a way higher precedence over if and if...else

Anonymous

@EriktheOutgolfer Oh right, I'm thinking of [a,b][cond]

Erik the Outgolfer

yeah that does evaluate b indeed

caird coinheringaahing

20:50

I bet no-one can tell me what this does :P /s

Anonymous

At this point I've internalized the Python golfing strats and now get the reasonings confused :P

Anonymous

@cairdcoinheringaahing Big-Omega

caird coinheringaahing

@Mego Huh?

Zacharý

Now JavaScript, that's a different story when it comes to random WTF's in it type system

Erik the Outgolfer

@Mego are you sure that's 100% true? I discover new Python golfing strats now and then

caird coinheringaahing

20:51

groans Don't get Mego started on JavaScript

Anonymous

@EriktheOutgolfer "the Python golfing strats", not "all of the Python golfing strats"

Zacharý

[]+[]

Anonymous

Obviously I can't internalize what I haven't learned, so your pedantry is unnecessary :P

Anonymous

@Zacharý It's less of a system and more of an accident

trichoplax

We don't practise pedantry because it's necessary, but because it's fun

Poke

20:53

Javascript is just a faster version of Java

3

trichoplax

The less necessary, the more fun

Zacharý

Apparently Java autoconverts in some cases where not even Python would

Anonymous

@Poke eye twitches

MD XF

@Poke (prepares for the flood of comments about that remarkably controversial message)

Poke

:)

Zacharý

20:54

JavaScript is Java if it were untyped and not OOP

Anonymous

Java is OOP, JavaScript is OOPS

15

trichoplax

JS is OOP now. Soon the two will converge

Poke

@Zacharý there are definitely some weird implicit casts but you're usually doing something silly if you encounter one

Mr. Xcoder

For a sec I thought OOPS was a paradigm ;P

Zacharý

@Poke string with integer

SnivyDroid

20:55

Can anyone help me with writing an interpreter for the esoteric lang i made up

I not too experienced with that xd

Anonymous

@Mr.Xcoder It is. It means "use something else" :P

Zacharý

@trichoplax never will JavaScript and Java merge

SnivyDroid

Hell no

Zacharý

@SnivyDroid flak.

Poke

@Zacharý you mean during concatenation? That's something I'd expect at least

SnivyDroid

20:56

That should be outlawed by the geneva convention

trichoplax

@Zacharý I knew someone would bite :P

Adám

@SnivyDroid Which language?

SnivyDroid

Combining a slow-compiling lang to a bloated lang would be a catastrophe

Zacharý

@Poke considering Python doesn't let you do that, I'd think not.

Erik the Outgolfer

Java and JS are in an eternal state of war

caird coinheringaahing

20:56

@SnivyDroid Sure, I wouldn't mind

SnivyDroid

@Adám Its one I made up

Zacharý

@Adám do you think it'd be APL

SnivyDroid

Its a palindromic alphabetical language

Mr. Xcoder

@Mego Then JS and C++ (I know you’ll disagree about the latter) are definitely OOPS :P

SnivyDroid

I call it ALPHA

Adám

20:57

Introducing Java²Script

SnivyDroid

lord no

Anonymous

@Mr.Xcoder C++ is a planned mistake that could be good if there weren't a few dozen competing interests steering its development

Zacharý

Which do you hate more, @SnivyDroid

caird coinheringaahing

Golfing tips?

Zacharý

@Mego D will forever be the best c-style language

Adám

20:58

@SnivyDroid OK… Do you have a design doc?

SnivyDroid

I can make one

yeah i forgot to do that whoop

Erik the Outgolfer

@Adám you sure? that would create uncontrollable forces which will instantly exterminate the human kind and our galaxy between the eternal, deadly war of the Javanese and the JavaScriptians

Mr. Xcoder

@cairdcoinheringaahing What fors that do?

SnivyDroid

Give me ten miniutes

caird coinheringaahing

@SnivyDroid What language is it (going to be) written in?

Zacharý

20:59

Javanese people might be offended :p

SnivyDroid

Preferrably python

Zacharý

@cairdcoinheringaahing Python

MD XF

@Mr.Xcoder C++ is OOPSHITWHATAMIDOING

DJMcMayhem

@cairdcoinheringaahing Try it online! is a bit shorter, and the output is the same. I'm not sure what the goal is though :P

SnivyDroid

thats the only language i know somewhat

Mr. Xcoder

20:59

Perfect for caird

caird coinheringaahing

@Mr.Xcoder Divisor sum of 10, 50, 120 and 54

Mr. Xcoder

Oh ok

caird coinheringaahing

@DJMcMayhem ಠ_ಠ

Zacharý

@DJMcMayhem I mentioned flak, right?

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