Ken Thompson wrote in his famous paper [1] about quines:
> If you have never done this, I urge you to try it on your own. The discovery of how to do it is a revelation that far surpasses any benefit obtained by being told how to do it
Every once in a while I give them a try but I couldn't yet create one and it frustrates me very much. Afraid of being denied that "revelation" I never dared to read his paper past that point. I'm afraid I might never read it because of my ego.
I hadn't written one until ~30 mins ago [1]. I cheated and looked at a Java quine (not particularly elegant, but easy to see what is going on.), but I wrote one for Virgil. Just think string substitution; a string with a hole in it and you substitute a copy of the string, quoted into the hole. Just one substitution suffices.
This was written by Yusuke Endoh, who also wrote this submission to the IOCCC that I remember being arguably more astonished when I saw it for the first time: https://www.youtube.com/watch?v=QMYfkOtYYlg (ASCII fluid dynamics).
Wow, that was cool, never found that one when I went on a deep dive after discovering their quine relay. The other amazing ASCII program of theirs that I love is the Qlobe: http://mamememo.blogspot.com/2010/09/qlobe.html?m=1
> This is more than a cool program – it's a computer science breakthrough! Apparently, you have discovered a method for constructing quines based on an arbitrary blueprint involving any amount of languages.
>
> Please write a technical paper describing your approach. I'm sure you'll have no trouble finding a CS journal that will publish it.
> mame:
> Okay I'll submit to the Journal of Universal Rejection.
Later:
> mame:
> I'll soon publish a book, "The world of obfuscated, esoteric, artistic programming". The book explains how to write a uroboros quine. Hence, I proudly close this issue.
> It also contains my almost all (about forty) works, including alphabet-only Ruby program, radiation-hardened quine, etc., and explains many techniques to write such programs.
> You can buy my book on amazon.co.jp. Unfortunately, it is written in Japanese, yet another esoteric language. I hope anyone can translate to English.
Note that the author made the challenge even harder by sorting the languages in alphabetical order:
> According to Endoh, the most challenging transitions were Befunge to BLC8 to brainfuck, as all three are esoteric. It runs through languages strictly in alphabetical order, so there was no opportunity to group easier-to-work-with languages together.
I am amazed. I have no idea how the hell could the author even do that.
Apparently, they have a book called "The world of obfuscated, esoteric, artistic programming", but it seems to be written in Japanese. I hope it will be translated to English someday, so I may learn this dark sorcery.
Last December I had the itch to do some blogging. As it happens, I wrote a four part series that explains in detail how to write quines and quine relays. The initial post can be found at https://drcabana.org/quine/
I am a longtime lurker and finally decided to join in order to comment on this thread. I hope that it is not inappropriate to post a link to my own take on this material. If it is, please accept my apologies and feel free to downvote/flag me out of existence.
While this is amazing, I should point out that for most languages he only needs to understand enough syntax to print strings and possibly unquote them. If you actually run this program into the first language, Ruby, the actual code (meant to be a Rust code) is as follows:
fn main(){print!("{}",("object QR extends App{print(\"(display \\\"printf(\\\\\\\"1d;s/.//;s/1/ the sum of a son and0/g;s/0/ twice/g;s/2/You are as bad as/g;s/3/ a son!Speak your mind!/g\\\\\\\\n#The Relay of Quine.\\\\\\\\n#Ajax, a man.\\\\\\\\n#Ford, a man.\\\\\\\\n#Act i: Quine.\\\\\\\\n#Scene i: Relay.\\\\\\\\n#[Enter Ajax and Ford]\\\\\\\\n#Ajax:\\\\\\\\n#\\\\\\\");function[]=f(s);for i=1:2:length(s),printf(\\\\\\\"2%s3\\\\\\\",part(dec2bin(hex2dec(part(s,i:i+1))),$:-1:2)),end;endfunction\\\\nf('[lots of hexdump]')\\\\nf('[lots of hexdump]')[snip]\\\\nprintf(\\\\\\\"\\\\\\\\n#[Exeunt]\\\\\\\");quit\\\")\");}"));}
...where `("object ... ;}")` part is a single string literal here. The actual quine stuff can be done in just one language at your choice, or can be assimilated into some other language where unquoting is a bit heavier. It is much easier than polyglots, where a single code should be interpreted in multiple languages.
Printing and unquoting strings is enough to write an ordinary quine (although getting it exactly right is still quite subtle).
Making a quine relay is substantially more complicated, because you don't just print the quoted string, you have to print the quoted version of a string in a different language, but that unwraps to the same thing 128 applications later!
If you still think it's easy, I reckon you should write us a quine relay of just 3 languages and then explain how simple it is.
In this video (where among the other things they explain huroboro), they show an example of code that prints out exactly the same output (itself) whether it's compiled/executed in c, python or ruby
Are we saying "can't do it in an interview without access to some resources", "can't do it in the amount of time I'm willing to learn the language", or truly a "I could never do this even if I dedicated time to it and had standard resources to work with"?
For me, I 'can't' do the first one even in languages I commonly use as I almost never write the code for the initial entry point. Either I'm working on an existing project of the IDE generates it and I never look closely at it so I'll likely mess something up.
If it is the second, it is more a of an 'I won't' do it in some languages. I don't doubt my ability to do it, I just don't have plans on learning many of these languages. I'll read an article on how BF works, but I don't plan to spend more time on it than that.
If it is the third option, then I'm quite bothered by level of defeatism in it and would be surprised by a programmer saying it. It is something I hear from people who took a coding class, barely passed, and decided not to touch the topic again. Even then I would challenge those people as having the ability to do it but having (entirely valid) reasons not to spend time on the attempt. (I make such a challenge because I think it is beneficial for people to not put themselves down and to draw a distinction between something they can't do and something they do have the power to do but don't have enough reason to do.)
Readit News
> If you have never done this, I urge you to try it on your own. The discovery of how to do it is a revelation that far surpasses any benefit obtained by being told how to do it
Every once in a while I give them a try but I couldn't yet create one and it frustrates me very much. Afraid of being denied that "revelation" I never dared to read his paper past that point. I'm afraid I might never read it because of my ego.
1: https://www.cs.cmu.edu/~rdriley/487/papers/Thompson_1984_Ref...
There is a delight in doing it, but don't overdo the anticipation. I've found greater delights in programming.
Yes, it seems Lisp wouldn't be appropriate for this.
[update: same program also works in python and ruby]
[1] https://github.com/titzer/virgil/blob/master/apps/Quine/Quin...
https://github.com/62726164/quine
https://github.com/mame/quine-relay/issues/10
> p-e-w:
> This is more than a cool program – it's a computer science breakthrough! Apparently, you have discovered a method for constructing quines based on an arbitrary blueprint involving any amount of languages. > > Please write a technical paper describing your approach. I'm sure you'll have no trouble finding a CS journal that will publish it.
> mame:
> Okay I'll submit to the Journal of Universal Rejection.
Later:
> mame:
> I'll soon publish a book, "The world of obfuscated, esoteric, artistic programming". The book explains how to write a uroboros quine. Hence, I proudly close this issue.
> It also contains my almost all (about forty) works, including alphabet-only Ruby program, radiation-hardened quine, etc., and explains many techniques to write such programs.
> You can buy my book on amazon.co.jp. Unfortunately, it is written in Japanese, yet another esoteric language. I hope anyone can translate to English.
Dead Comment
Note that the author made the challenge even harder by sorting the languages in alphabetical order:
> According to Endoh, the most challenging transitions were Befunge to BLC8 to brainfuck, as all three are esoteric. It runs through languages strictly in alphabetical order, so there was no opportunity to group easier-to-work-with languages together.
Apparently, they have a book called "The world of obfuscated, esoteric, artistic programming", but it seems to be written in Japanese. I hope it will be translated to English someday, so I may learn this dark sorcery.
Dead Comment
I am a longtime lurker and finally decided to join in order to comment on this thread. I hope that it is not inappropriate to post a link to my own take on this material. If it is, please accept my apologies and feel free to downvote/flag me out of existence.
This guy demonstrated enough understanding of 128 of them to make this work.
Is the difference in competence really so big between us?
Making a quine relay is substantially more complicated, because you don't just print the quoted string, you have to print the quoted version of a string in a different language, but that unwraps to the same thing 128 applications later!
If you still think it's easy, I reckon you should write us a quine relay of just 3 languages and then explain how simple it is.
https://youtu.be/6avJHaC3C2U?t=1957
Are we saying "can't do it in an interview without access to some resources", "can't do it in the amount of time I'm willing to learn the language", or truly a "I could never do this even if I dedicated time to it and had standard resources to work with"?
For me, I 'can't' do the first one even in languages I commonly use as I almost never write the code for the initial entry point. Either I'm working on an existing project of the IDE generates it and I never look closely at it so I'll likely mess something up.
If it is the second, it is more a of an 'I won't' do it in some languages. I don't doubt my ability to do it, I just don't have plans on learning many of these languages. I'll read an article on how BF works, but I don't plan to spend more time on it than that.
If it is the third option, then I'm quite bothered by level of defeatism in it and would be surprised by a programmer saying it. It is something I hear from people who took a coding class, barely passed, and decided not to touch the topic again. Even then I would challenge those people as having the ability to do it but having (entirely valid) reasons not to spend time on the attempt. (I make such a challenge because I think it is beneficial for people to not put themselves down and to draw a distinction between something they can't do and something they do have the power to do but don't have enough reason to do.)
I see this every single day.
And it becomes more and more obvious the better you become.