221
\$\begingroup\$

Using your language of choice, golf a quine.

A quine is a non-empty computer program which takes no input and produces a copy of its own source code as its only output.

No cheating -- that means that you can't just read the source file and print it. Also, in many languages, an empty file is also a quine: that isn't considered a legit quine either.

No error quines -- there is already a separate challenge for error quines.

Points for:

  • Smallest code (in bytes)
  • Most obfuscated/obscure solution
  • Using esoteric/obscure languages
  • Successfully using languages that are difficult to golf in

The following Stack Snippet can be used to get a quick view of the current score in each language, and thus to know which languages have existing answers and what sort of target you have to beat:

var QUESTION_ID=69;
var OVERRIDE_USER=98;

var ANSWER_FILTER="!t)IWYnsLAZle2tQ3KqrVveCRJfxcRLe";var COMMENT_FILTER="!)Q2B_A2kjfAiU78X(md6BoYk";var answers=[],answers_hash,answer_ids,answer_page=1,more_answers=!0,comment_page;function answersUrl(index){return"https://api.stackexchange.com/2.2/questions/"+QUESTION_ID+"/answers?page="+index+"&pagesize=100&order=desc&sort=creation&site=codegolf&filter="+ANSWER_FILTER}
function commentUrl(index,answers){return"https://api.stackexchange.com/2.2/answers/"+answers.join(';')+"/comments?page="+index+"&pagesize=100&order=desc&sort=creation&site=codegolf&filter="+COMMENT_FILTER}
function getAnswers(){jQuery.ajax({url:answersUrl(answer_page++),method:"get",dataType:"jsonp",crossDomain:!0,success:function(data){answers.push.apply(answers,data.items);answers_hash=[];answer_ids=[];data.items.forEach(function(a){a.comments=[];var id=+a.share_link.match(/\d+/);answer_ids.push(id);answers_hash[id]=a});if(!data.has_more)more_answers=!1;comment_page=1;getComments()}})}
function getComments(){jQuery.ajax({url:commentUrl(comment_page++,answer_ids),method:"get",dataType:"jsonp",crossDomain:!0,success:function(data){data.items.forEach(function(c){if(c.owner.user_id===OVERRIDE_USER)
answers_hash[c.post_id].comments.push(c)});if(data.has_more)getComments();else if(more_answers)getAnswers();else process()}})}
getAnswers();var SCORE_REG=(function(){var headerTag=String.raw `h\d`
var score=String.raw `\-?\d+\.?\d*`
var normalText=String.raw `[^\n<>]*`
var strikethrough=String.raw `<s>${normalText}</s>|<strike>${normalText}</strike>|<del>${normalText}</del>`
var noDigitText=String.raw `[^\n\d<>]*`
var htmlTag=String.raw `<[^\n<>]+>`
return new RegExp(String.raw `<${headerTag}>`+String.raw `\s*([^\n,]*[^\s,]),.*?`+String.raw `(${score})`+String.raw `(?=`+String.raw `${noDigitText}`+String.raw `(?:(?:${strikethrough}|${htmlTag})${noDigitText})*`+String.raw `</${headerTag}>`+String.raw `)`)})();var OVERRIDE_REG=/^Override\s*header:\s*/i;function getAuthorName(a){return a.owner.display_name}
function process(){var valid=[];answers.forEach(function(a){var body=a.body;a.comments.forEach(function(c){if(OVERRIDE_REG.test(c.body))
body='<h1>'+c.body.replace(OVERRIDE_REG,'')+'</h1>'});var match=body.match(SCORE_REG);if(match)
valid.push({user:getAuthorName(a),size:+match[2],language:match[1],link:a.share_link,})});valid.sort(function(a,b){var aB=a.size,bB=b.size;return aB-bB});var languages={};var place=1;var lastSize=null;var lastPlace=1;valid.forEach(function(a){if(a.size!=lastSize)
lastPlace=place;lastSize=a.size;++place;var answer=jQuery("#answer-template").html();answer=answer.replace("{{PLACE}}",lastPlace+".").replace("{{NAME}}",a.user).replace("{{LANGUAGE}}",a.language).replace("{{SIZE}}",a.size).replace("{{LINK}}",a.link);answer=jQuery(answer);jQuery("#answers").append(answer);var lang=a.language;lang=jQuery('<i>'+a.language+'</i>').text().toLowerCase();languages[lang]=languages[lang]||{lang:a.language,user:a.user,size:a.size,link:a.link,uniq:lang}});var langs=[];for(var lang in languages)
if(languages.hasOwnProperty(lang))
langs.push(languages[lang]);langs.sort(function(a,b){if(a.uniq>b.uniq)return 1;if(a.uniq<b.uniq)return-1;return 0});for(var i=0;i<langs.length;++i)
{var language=jQuery("#language-template").html();var lang=langs[i];language=language.replace("{{LANGUAGE}}",lang.lang).replace("{{NAME}}",lang.user).replace("{{SIZE}}",lang.size).replace("{{LINK}}",lang.link);language=jQuery(language);jQuery("#languages").append(language)}}
body{text-align:left!important}#answer-list{padding:10px;float:left}#language-list{padding:10px;float:left}table thead{font-weight:700}table td{padding:5px}
 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <link rel="stylesheet" type="text/css" href="https://cdn.sstatic.net/Sites/codegolf/primary.css?v=f52df912b654"> <div id="language-list"> <h2>Winners by Language</h2> <table class="language-list"> <thead> <tr><td>Language</td><td>User</td><td>Score</td></tr></thead> <tbody id="languages"> </tbody> </table> </div><div id="answer-list"> <h2>Leaderboard</h2> <table class="answer-list"> <thead> <tr><td></td><td>Author</td><td>Language</td><td>Size</td></tr></thead> <tbody id="answers"> </tbody> </table> </div><table style="display: none"> <tbody id="answer-template"> <tr><td>{{PLACE}}</td><td>{{NAME}}</td><td>{{LANGUAGE}}</td><td><a href="{{LINK}}">{{SIZE}}</a></td></tr></tbody> </table> <table style="display: none"> <tbody id="language-template"> <tr><td>{{LANGUAGE}}</td><td>{{NAME}}</td><td><a href="{{LINK}}">{{SIZE}}</a></td></tr></tbody> </table> 

\$\endgroup\$
3
  • 4
    \$\begingroup\$ Do you not mean, "Golf you a quine for greater good!"? \$\endgroup\$ May 3 '11 at 2:49
  • 58
    \$\begingroup\$ @muntoo it's a play on "Learn you a Haskell for Great Good". \$\endgroup\$ May 3 '11 at 2:52
  • 10
    \$\begingroup\$ Did anybody notice that this is question 69? \$\endgroup\$
    – aidan0626
    Oct 24 '20 at 22:47

402 Answers 402

1
4 5
6
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14
4
\$\begingroup\$

Operation Flashpoint scripting language,  22  15 bytes

q={"q={"+q+"}"}

Call with:

hint call q

Output:

q={"q={"+q+"}"}

Old version (22 bytes):

q={format["q={%1}",q]}
\$\endgroup\$
4
\$\begingroup\$

JavaScript, 53 bytes

A quine without any uses of uneval or Function.prototype.toString.

Q="q=Q.link()[8];alert(`Q=${q+Q+q};eval(Q)`)";eval(Q)

Can avoid use of template strings for + 1 byte.

Q="q=Q.link()[8];alert('Q='+q+Q+q+';eval(Q)')";eval(Q)


JavaScript, 74 bytes

Another approach avoiding uneval and Function.prototype.toString:

console.log(a="console.log(a=%s%s%s,q=a.link()[8],a,q)",q=a.link()[8],a,q)

\$\endgroup\$
4
+400
\$\begingroup\$

Pain-Flak, 2009 bytes

><))(())(())()(())(())()(())(())(())(())()()(())()(())(())()()()(())(())()(())(())()()(())(())(())()(())(())()()(())(())(())()(())(())()(())(())()(())(())()(())()(())()(())()(())()(())(())(())()()(())()()(())(())(())()()(())(())(())()()()(())(())(())()()()(())(())()()(())()(())()()(())(())()()()(())(())(())(())(())(())()(())()()()(())()(())()()(())(())()()()(())(())(())()()()(())(())()()(())()(())(())()()(())()()(())(())(())()()(())(())(())(())(())(())()()()(())(())(())()()(())(())(())(())()()(())()()(())()()()(())(())()()(())()(())(())()()(())(())(())(())(())(())()()(())()()()(())(())()(())(())()()(())()(())()()(())()()()(())(())()()(())(())(())(())(())(())()()(())()()()(())()(())(())()(())()()(())(())()(())()()()()(())()(())(())(())(())(())(())(())(())()(())(())(())()()(())()(())(())(())(())(())()()()(())()(())(())()()(())(())(())()()(())()(())(())(())()()(())()(())()(())(())(())(())()()(())()(())()()()()(())()(())()(())()()()(())(())(())()(())(())()()(())(())(())()()(())()(())(())(())()()(())()(())()(())(())(())()()(())(())(())()(())(())()(())(())()(())(())()(())(())()(())()(())()(())()(())()()()(())(())()(())(())()()(())()(())()(())()()()(())()(())(())(())()(())()()()()(())()()(())(())()(())()(())(())(())(())()()(())(())(())()()()(())(())(())()()()(())(())()()(())()(())()()(())(())()()()(())(())(())()()()(())(())(())(())()(())(())(())(())()(())()()()()(())(())()()(())()(())()(())()(())(())()()()(())(())(())()(())(())()()(())()(())()()(())()()()(())(())()(())(())(())(())()()(())()()()()(())()(())()(())(())()()()(())(())(())()(())(())(())()()(())(())(())()()(())(())(())()()(())(())(())()(())(())()(())(())()(())(())()(())(())()(())()(())()(())()(())()(())()(())(())()()()(())()()((}><))))))()()()()((}{(}{(}{()((><))]}{[()(>})}{)((><)))}{])([()(((><{><})}{><(><{}{<())(}])([)>))}{)(>))))()()()()((}{())}{()}{(}{)((>))])}{([))}{()}{(}{)><((()}{()((<(<(()])(})()>}{<({[}{>})}{)(>}{<({<}{)}{>}}{{<}{(><(<({}{(}}{)}{><(><})>)(<({{><})}{><(><{}{{}}{{)))))()()()((}{)((}{)(><)}{(()()((

Try it online!

(Trailing newline because the interpreter outputs a newline.)

-176 bytes by improving the Brain-Flak quine

Basically a straight port of my Brain-Flak quine. The only major difference is the >< at the beginning, which is required in order to keep the data section out of the output.

><                 switch to right stack; effectively does nothing since both stacks are empty
))((...))()()((    data, same format as the Brain-Flak quine
}main loop{        same as the Brain-Flak quine, but with different constants
}}{{               clear current stack; this does nothing
)))))()()()((}{)((}{)(><)}{(()()((   push opening >< at beginning of code

Since this is Pain-Flak, the code also goes backward after it is finished going forward. As such, I had to ensure that this does not mess up the output.

))()())}{(><)(}{))(}{))()()()(((((   push 70, 68, 5, 4 on right stack
}}{{               clear right stack
}pool niam{        do nothing because top of stack is zero
))()()((...))((    push constants on right stack in reverse order
><                 switch to left stack and implicitly output
\$\endgroup\$
5
  • 1
    \$\begingroup\$ The only Pain-Flak solutions I've seen are ones directly translated from Brain-Flak... \$\endgroup\$
    – Jo King
    Apr 10 '18 at 5:21
  • \$\begingroup\$ I will give the bounty but kinda lame that it is just a port \$\endgroup\$ Apr 25 '18 at 10:39
  • \$\begingroup\$ @Christopher it is your fault that you made Pain-Flak so similar to Brain-Flak :P \$\endgroup\$
    – ASCII-only
    Apr 30 '18 at 22:13
  • \$\begingroup\$ @ascii painflak update is removing swap stack \$\endgroup\$ Apr 30 '18 at 22:47
  • \$\begingroup\$ @Christopher then it'll just be translated Mini-flak? \$\endgroup\$
    – ASCII-only
    Apr 30 '18 at 23:09
4
\$\begingroup\$

Reflections, 9228 bytes

As the program has 8620 lines, I won't put it here completely.

First line:

\

Then, for each character in the last part (below), there are n newlines for ASCII character n, followed by:

+
#

After it, the last part is (the # is actually already covered by the previous section):

#  /  \          /+\  /#_=0v\
>~ <       /(1:1)#@/       ~
\(0/      2)     \3)(2:2)(3^ 0#+#@
           \:(24):(4#_#_#_  /
      +               \*             (4\
      \*(1(2                          +/

Test it!

Working on explanation.

I had to fix a bug in the interpreter for this one. Does that count as adding a feature just for a challenge?

\$\endgroup\$
1
  • 1
    \$\begingroup\$ :| the URL encoding format is terrible \$\endgroup\$
    – ASCII-only
    May 22 '18 at 0:57
4
\$\begingroup\$

2DFuck, 1352 1289 bytes

!xv>>>>x>x>>>>>>x>x>x>x>>x>x>x>>x>x>>x>x>x>x>x>>x>x>>x>x>>x>x>x>x>x>>x>x>x>x>x>>x>x>x>x>>x>x>>x>x>x>>x>x>>x>>>x>>>>>>x>>>>>x>>x>>>x>x>>x>>>x>>>>>>x>x>x>>>>>x>>>x>>>x>x>>x>x>x>x>x>>x>x>x>x>>>x>x>x>x>>x>x>x>x>x>x>>x>x>>>>>>>>>>x>x>>>>>x>>x>>>x>x>>x>>>x>>>>>>x>>>>>x>>x>>>x>x>>x>>>x>>>>>>x>x>x>>>>>x>>>x>>>x>x>x>>x>x>>x>x>>x>x>x>x>>x>x>>>x>x>>>>x>>x>>>x>>>>>>>>>>x>>>x>>>x>x>x>>x>x>>x>x>x>x>x>>x>x>>x>>>x>x>>>>x>>x>>>x>>>>>>>>>>x>>>x>>>>>>>>>>x>>>x>>>x>x>>x>x>>x>x>>x>x>x>x>>x>x>>x>x>>x>>>x>x>>>>x>>x>>>x>>>x>x>>x>x>>x>x>>x>x>x>>x>x>>x>x>x>>x>>>x>x>>>>>x>>>>x>x>>>>x>>x>>>x>>>>>>>>>>x>>>x>>>x>x>>x>x>x>x>>x>x>x>>x>x>>x>x>>>x>x>>>>x>>x>>>x>>>>>>>>>>x>>x>>>x>>>x>x>x>>x>x>x>x>x>x>>x>x>>>x>x>>>>x>>>x>>>>>>>>>>x>>x>>>x>>>x>x>x>>x>x>x>x>x>>x>x>x>>>x>x>>>>x>>>x>>>>>>>>>>x>>x>>>x>>>x>x>>x>x>>x>x>>x>x>x>x>x>>x>x>>>x>x>>>>x>>>x>>>>>>>>>>x>>>x>>>x>x>>x>x>x>x>x>>x>x>x>x>>>x>x>>>>x>>x>>>x>>>x>x>>x>x>x>x>>x>x>>x>x>x>>x>x>>>x>x>>>x>x>>>x>x>>>x>x>>>x>x>>>>>x>>>>x>x>>>>>>>>x>x>>>x>x>>>>>>>>>>x>x>>>>>x>>x>>>x>x>^x!..!.!....!.!.!....!....!...!.!..!.![<r!]![vr[!.!....!...]..!.....!.>^r!]![<r!]![vr[!..!.!.!...!.]r![>r[!..!.!....!.!]r![>r[>r[!.!.!.!...!.!.!]r![!.!.!.!..!.!..!]<]r![>r[!.!...!..!.!.]r![>r![!..!.....!.]r[>r![!..!....!..]r[>r![!.!.!.!....!.]r[>r[!.!....!...]r![!.!...!.!..!.]]]]]<]>]]>^r!]

Try it online!

Shaved off 63 bytes with Huffman coding! New explanation in progress.

\$\endgroup\$
1
  • \$\begingroup\$ Some thoughts; you can reverse the data encoding to avoid the second ![<r!], and you can save some bytes through reusing .s (for example all characters have a leading zero). 1131 bytes. I think you might get better huffman encoding through multiple or partial characters \$\endgroup\$
    – Jo King
    Sep 18 '20 at 7:51
4
\$\begingroup\$

Z80Golf, 120 bytes

00000000: 21f5 76e5 2180 10e5 21cd 00e5 2180 7ce5  !.v.!...!...!.|.
00000010: 21cd 00e5 21e1 7de5 2106 14e5 2110 e8e5  !...!.}.!...!...
00000020: 2100 80e5 21e5 cde5 211b 3ee5 2100 80e5  !...!...!.>.!...
00000030: 211a cde5 2180 13e5 21cd 00e5 211b 1ae5  !...!...!...!...
00000040: 2180 1be5 21cd 00e5 213e 21e5 2106 14e5  !...!...!>!.!...
00000050: 0614 3e21 cd00 801b 1b1a cd00 8013 1acd  ..>!............
00000060: 0080 1b3e e5cd 0080 10e8 0614 e17d cd00  ...>.........}..
00000070: 807c cd00 8010 f576                      .|.....v

Try it online!

Verification:

$ ./z80golf a.bin | xxd
00000000: 21f5 76e5 2180 10e5 21cd 00e5 2180 7ce5  !.v.!...!...!.|.
00000010: 21cd 00e5 21e1 7de5 2106 14e5 2110 e8e5  !...!.}.!...!...
00000020: 2100 80e5 21e5 cde5 211b 3ee5 2100 80e5  !...!...!.>.!...
00000030: 211a cde5 2180 13e5 21cd 00e5 211b 1ae5  !...!...!...!...
00000040: 2180 1be5 21cd 00e5 213e 21e5 2106 14e5  !...!...!>!.!...
00000050: 0614 3e21 cd00 801b 1b1a cd00 8013 1acd  ..>!............
00000060: 0080 1b3e e5cd 0080 10e8 0614 e17d cd00  ...>.........}..
00000070: 807c cd00 8010 f576                      .|.....v

$ ./z80golf a.bin | diff -s a.bin -
Files a.bin and - are identical

Looks like no one tried to make a proper quine in machine code yet, so here is one.

Although the machine code is loaded to memory, it does NOT read any address occupied by the code. Instead, it uses the stack space to setup required data.

Disassembly

start:
  ld hl, $76f5
  push hl
  ld hl, $1080
  push hl
  ld hl, $00cd
  push hl
  ld hl, $7c80
  push hl
  ld hl, $00cd
  push hl
  ld hl, $7de1
  push hl
  ld hl, $1406
  push hl
  ld hl, $e810
  push hl
  ld hl, $8000
  push hl
  ld hl, $cde5
  push hl
  ld hl, $3e1b
  push hl
  ld hl, $8000
  push hl
  ld hl, $cd1a
  push hl
  ld hl, $1380
  push hl
  ld hl, $00cd
  push hl
  ld hl, $1a1b
  push hl
  ld hl, $1b80
  push hl
  ld hl, $00cd
  push hl
  ld hl, $213e
  push hl
  ld hl, $1406
  push hl

  ld b, 20
loop1:
  ld a, $21
  call $8000
  dec de
  dec de
  ld a, (de)
  call $8000
  inc de
  ld a, (de)
  call $8000
  dec de
  ld a, $e5
  call $8000
  djnz loop1

  ld b, 20
loop2:
  pop hl
  ld a, l
  call $8000
  ld a, h
  call $8000
  djnz loop2

  halt

At start, the stack pointer sp is zero, just like other registers. Pushing some values causes sp to decrease, so the values are stacked in the memory region $ffxx.

The combination ld hl, $xxxx and push hl seems like the best option to dump predefined values into some memory space. It takes 4 bytes to store 2 bytes; any other option I could think of uses 3 or more bytes to store only one byte.

The first loop prints the ld hl, $xxxx (21 xx xx) and push hl (e5) instructions for the data, from the bottom of the stack (the address, represented by de, is decreased starting from $0000).

ld b, $xx and djnz label combined forms a fixed-times looping construct. It is only 4 bytes, which is optimal in Z80 (unless the loop count is already saved in another register).

But there is an endianness problem here, so simply sweeping the memory addresses in decreasing order does not work. So I had to add a pair of dec de and inc de at the cost of 2 bytes (plus 4 bytes to push the 2 bytes into the stack).

The second loop prints the main code by popping data from the stack.

Possible improvement ideas

Since the code is longer than $38 or 56 bytes, we can't use rst $38 in place of call $8000. Having call $8000 6 times in total, it's a great opportunity for golf. I considered placing call $8000; ret at address $38, but then I have to reduce the main code into 26 bytes or lower.

I also thought of moving the code to the front by adding some jr, so that I can embed the call $8000; ret in the code part. But then I can't use the efficient "pop and print" loop. It prints the data in reverse order of pushing, so it can't be used to print the push part; the "print" overwrites the stack with the return address, so it can't be used to print the first part either.

Finally, there is room for alternative encoding since some bytes frequently appear in the code. But Z80 itself is severely limited in arithmetic...

\$\endgroup\$
4
\$\begingroup\$

J, 27 bytes

echo(,quote)'echo(,quote)'

Try it online!

It's surprising that there's no proper J quine submission yet.

How it works

echo(,quote)'echo(,quote)'
            'echo(,quote)'  The string `s`
      quote                 Wrap `s` with single quotes
     ,                      Concat s to the above; `(f g)x` is equal to `x f g x`
echo                        Explicitly print the result

echo is needed because the result of a non-REPL line is not printed.

\$\endgroup\$
4
\$\begingroup\$

MathGolf, 9 bytes

ÿ_'ÿ¬_'ÿ¬

Try it online!

Explanation:

ÿ_'ÿ¬_'ÿ¬
ÿ          Start string of length 4
 _'ÿ¬      Push "_'ÿ¬"
     _     Duplicate it
      'ÿ   Push the character "ÿ"
        ¬  Rotate stack so the "ÿ" is at the bottom
           Implicitly output "ÿ", "_'ÿ¬", "_'ÿ¬" join together
\$\endgroup\$
1
  • \$\begingroup\$ ÿ'ÿ¬_'ÿ¬_ is another 9-byter. \$\endgroup\$
    – maxb
    Jan 7 '19 at 11:56
4
\$\begingroup\$

Symbolic Python, 30 bytes

_="_='_='+`_`+';__(_)'";__(_)

Try it online!

Yet another eval quine. The lack of being able to do %r in Symbolic Python is made up for Python 2's backticks, which are an alias for the repr function.

Explanation:

_="                   ";       # Assign the string to the _ variable
                        __(_)  # Eval the string
   _=                          # Assign to the _ variable
     '_='                      # The initial _=
         +`_`                  # The Python representation of the string
             +';__(_)'         # And the final evaling part
                               # Implicitly output the contents of _

An alternative that doesn't use the rather long eval function comes to 31 bytes, but I actually like it more.

_=';_="_="+`_`+_';_="_="+`_`+_

Try it online!

\$\endgroup\$
4
\$\begingroup\$

Golunar, 951 bytes (394.25 bytes as an integer value)

19370043316195921194914466480856680152267470323963447024756684537596068724128114478400203537500358028693578705195025299449504112473728653294217406768139954805008550643064305270958743186186490023003785512463398359429631224818444304976679217098389450981926661910005004089131207223929032173888419619738722341444212432611576207643452266161684471788295034889655803444137372629364500165719019777515305922257911642994836581634099155833200157295629218533465854143898419293035289733581625252699105530843807023973345521520887128012736565874423200184723012755626596238647926406709693583878890472621210970350861368171259284533764490596207310864352873729240842719608391238098412446205860013948766486129442046252306334230243913196704614648889659870117069927719874852423159076941049170045933025772364248625729725500550726133134993128102614696728457139079375133324957922066270555810085574853273966267981675757808791933974619299446035844180580831907739236954600685575

Golunar is the decimal representation of the number of zeros that a Unary code would need. It translates to this brainfuck code:

->+>+>+>>>>>>>>>>>>+>+>>>+>+>+>+>+>>>>>>+>>>+>>>+>>>+>>>+>>>+>>+>>>>+>+>>+>>>+>>>+>>>+>>>+>>>+>>>+>>>+>+>>>>>>>+>+>+>+>>>+>>>>+>+>+>>>+>+>+>>+>>+>>>+>+>+>+>+>+>>>>>+>+>+>>>+>+>+>>>>>>>>+>+>>>>>+>>+>>>+>>>+>+>>+>+>+>>+>>+>>>+>+>>>+>+>>+>+>+>+>>+>>>+>+>+>>>>>+>+>+>>>+>+>+>>>>>>>>+>+>>>>>>>+>+>+>+>>>+>>>>+>>+>+>+>+>+>>>>>>+>>+>>>>+>+>>>>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>+>>>>>>+>>>+>>+>+>+>+>+>>>+>+>+>>>+>>>+>+>>+>+>>+>+>>+>+>>+>+>>+>+>>+>+>>+>+>>>>>>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>>>+>+>>>+>+>+>>>+>+>>+>+>+>>+>>+>>>+>+>>>+>+>>+>+>>+>>>+>>>>>>+>>>+>>>>>>+>>>+>>+>+>+>>>>>+>+>+>+>>>>>>+>>>>>>+>>+>+>+>>+>>+>>>+>>>+>+>+>+>>>>+>+>+>+>>+>>>+>>>+>+>+>>>>>+>+>>>>>>>+>+>+>+>+>>+>>>+>+>+>+>>>>+>+>>+>>>>>>+>>>+>>>>>>+>>+>+>+>>>>>+>+>>+>>>>>>>>>+>+>>+>+>>+>+[[>>+[>]+>++>+[<]<-]>>[>]<<-[<]<<+]+>+>-[>]++>++>++[[-<+]-<[-<[>++<-[>++<-[>++<-[>++<-[>--------<<[-]++>-[>++<-]]]]]]>[<+>-]+<<]>>[>>]<[>]<-[[-<+]-<<+>[>>]<[>]]<+]<[<<]>>[+++++++[<++++++>-]<.>>>]

Try it online!

I couldn't find an online Golunar interpreter, but you can use this Golunar to brainfuck converter to get the brainfuck code and then execute it.

This code is inspired by a brainfuck quine of Eric Bosman and Daniel B Cristofani. First it reads a list of bits that represent the bit-codes of the code part, then it builds up a list of bits that represent the ">" and "+" characters needed to print the first list. Those lists are merged and hold the binary value of the Golunar code. In the last step, the decimal value of the binary number are computed and printed.

[ 
tape: [decimal digits], value start marker/VS(-1)(starting cell), [input bits], between binary marker/BB(0), [binary output data]

input bits are 0 or 1, output bits are in reversed order and have the values 1(used) or 2(used and set)
input must be given in reversed order

decimal digits consist of two cells per value (value, digit used marker(DU)(1))

bit values:
> 000
< 001
+ 010
- 011
. 100
, 101
[ 110
] 111

]

-                       set VS

                    set input bits
>+>+>+>>>>>>>>>>>>+>+>>>+>+>+>+>+>>>>>>+>>>+>>>+>>>+>>>+>>>+>>+>>>>+>+>>+>>>+>>>+>>>+>>>+>>>+>>>+>>>
+>+>>>>>>>+>+>+>+>>>+>>>>+>+>+>>>+>+>+>>+>>+>>>+>+>+>+>+>+>>>>>+>+>+>>>+>+>+>>>>>>>>+>+>>>>>+>>+>>>+
>>>+>+>>+>+>+>>+>>+>>>+>+>>>+>+>>+>+>+>+>>+>>>+>+>+>>>>>+>+>+>>>+>+>+>>>>>>>>+>+>>>>>>>+>+>+>+>>>+>>
>>+>>+>+>+>+>+>>>>>>+>>+>>>>+>+>>>>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>+>
>>>>>+>>>+>>+>+>+>+>+>>>+>+>+>>>+>>>+>+>>+>+>>+>+>>+>+>>+>+>>+>+>>+>+>>+>+>>>>>>+>+>+>+>>+>>>>+>>>+>
>>>>>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>+>>+>>>>+>>>+>>>>>>+>+>+>>>+>+>>>+>+>+>
>>+>+>>+>+>+>>+>>+>>>+>+>>>+>+>>+>+>>+>>>+>>>>>>+>>>+>>>>>>+>>>+>>+>+>+>>>>>+>+>+>+>>>>>>+>>>>>>+>>+
>+>+>>+>>+>>>+>>>+>+>+>+>>>>+>+>+>+>>+>>>+>>>+>+>+>>>>>+>+>>>>>>>+>+>+>+>+>>+>>>+>+>+>+>>>>+>+>>+>>>
>>>+>>>+>>>>>>+>>+>+>+>>>>>+>+>>+>>>>>>>>>+>+>>+>+>>+>

                    list rebuilding loop: append bits for "greater than" and plus symbols to the right of input data
+[                      for each input bit
  [                     while bit is greater than 0
    >>+                 copy bit to out data
    [>]+>++>+           append bits for plus (used markers plus 010)
    [<]<-               decrement in value
  ]
  >>[>]<<-              change most right character from plus to gt (010 to 000)
  [<]                   return to BB
  <<+                   repeat if not on VS
]
+>+>-                   prepare binary to decimal routine: set VS DU and first 1

[>]++>++>+              append bits for minus (011)

                    binary to decimal loop: use "double and add algorithm" to calculate the digits of the decimal value
+[                      if not on VS then
  [-<+]-                restore current bit value and go to VS
  <                     go to first DU
  [                 digit doubling loop
    -<                  remove DU and go to corresponding digit
    [
      >++<-             decrement current value and add 2 to temp value four times
      [
        >++<-
        [
          >++<-
          [
            >++<-
            [                   if value was greater than 4 then
              >---- ----        subtract 8 from temp
              <<[-]++           set next digit temp = 2 (DU plus 1)
              >-                decrement current digit
              [>++<-]           set temp = remaining value * 2
            ]
          ]
        ]
      ]
    ]
    >[<+>-]             set current digit = temp
    +                   set DU
    <<                  go to next digit
  ]                 end of digit doubling loop
  >>[>>]<[>]<           go to current bit
  -[                    if bit is 2 (used plus 1)
    [-<+]-              delete bit and go to VS
    <<+                 increment least significant digit
    >[>>]<[>]           go to current bit
  ]
  <+                    if not on VS then repeat  
]                   end of binary to decimal loop

<[<<]>                  go to most significant digit
>[                  printing loop: for each DU print corresponding value
  +++++++[<++++++>-]<.  add 48 to value (ASCII 0) and print
  >>>                   go to next DU
]
\$\endgroup\$
4
\$\begingroup\$

Keg, 49 43 bytes

\^\(\\\\\,\:\&\^\&\^\,\)\^\#^(\\,:&^&^,)^#

Try it online!

(note the trailing newline...)

-6 bytes thanks to Jo King reminding me that comments exist

This is a horrible mess, and I'm sure it can be outgolfed easily by someone comfortable with Keg's stack, and/or once "/' stop erroring. The first two thirds simply push each character from the last third to the stack in order (such that the last character is on top), and then the last third:

^                   Reverses the stack (such that the first character is on top),
 (         )        then does the following for each item CURRENTLY on the stack:
  \\,               print a backslash,
     :              duplicate the top of the stack,
      &             pop it to the register,
       ^            flip the stack,
        &           push the register,
         ^          flip the stack again,
          ,         and pop and print the top of the stack;
            ^       finally reversing what's left on the stack
             #\n    and commenting out the trailing newline,
                    so the stack is then implicitly printed bottom first,
                    with a trailing newline.

Essentially, it prints the first two thirds while copying itself onto the bottom of the stack, then flips the copy to be implicitly printed.

\$\endgroup\$
2
  • \$\begingroup\$ Thanks, fixed now... wait no \$\endgroup\$ Oct 1 '19 at 5:15
  • \$\begingroup\$ Now it's fixed \$\endgroup\$ Oct 1 '19 at 5:44
4
\$\begingroup\$

Keg, 21 bytes

HBZLTXJMIC(":,48*-)#

Try it online!

The string of letters translates to the code section reversed and shifted up by 32. It's lucky all the characters used are in the correct range for shifting.

Explanation:

(       )    # Loop over the stack
 "           # Shift stack left
  :          # Duplicate the letter
   ,         # Print the letter
    48*-     # Subtract 32 from the ordinal value of the letter
         #   # Comment out the newline
             # Print the shifted characters with a trailing newline
\$\endgroup\$
4
\$\begingroup\$

BaCon, 54 bytes

Without using the SOURCE$ variable, the smallest Quine is 55 bytes:

s$="s$=%c%s%c:?34,s$,34 FORMAT s$":?34,s$,34 FORMAT s$
\$\endgroup\$
4
  • 2
    \$\begingroup\$ please make the main part of the post the 55 byte noncheating quine \$\endgroup\$ Oct 14 '16 at 21:05
  • \$\begingroup\$ Done. I wonder why using 'SOURCE$' is cheating, looking at the other contributions? \$\endgroup\$
    – Peter
    Oct 15 '16 at 20:05
  • 1
    \$\begingroup\$ The other answers are also cheating. This challenge is over five years old; most answers were posted before we had clearly defined rules. Since last month, improper quines are officially forbidden in all challenges, even if the spec doesn't explicitly forbid them. \$\endgroup\$
    – Dennis
    Oct 15 '16 at 20:13
  • \$\begingroup\$ Thanks for pointing me to this page, I was unaware of it. \$\endgroup\$
    – Peter
    Oct 16 '16 at 20:29
4
\$\begingroup\$

MAWP, 60 bytes

Thanks @JoKing for saving a whopping 55 bytes!

48923792915350878792773358929392915992930\%\[52WW\M!:\]\[;\]

Try it!

It's finally done!

Explanation:

The quine is essentially split into three parts. The first part is the data, and is represented by the big blob of numbers in the start (excluding a 0). It represents the ASCII codes of the rest three parts of the code. The second part is the decoder that both turns the long stack of separate numbers into a smaller stack with multi-digit numbers and prints it as numbers without destroying it. The last part loops over the stack and prints it as ASCII. Note that we don't have to preserve the data in stack any more.

Old solution:

115 bytes

481263753508787774753508787775350878777479153508787774793479133584793479159930~%52WWM/52WWM52WWM/[52WWM/]/[!:/]/[;]
\$\endgroup\$
8
  • \$\begingroup\$ @JoKing - the auto-pasting of the code in the link doesn't seem to work (at least for the Mac OS X browsers that I've tried), and it's difficult to extract the code from the link itself. Could you include the code itself in a comment? \$\endgroup\$ Aug 17 '20 at 7:53
  • \$\begingroup\$ @DominicvanEssen could you possibly describe the issue with the auto-copy on the interpreter? I myself work on a Mac, but had no issues developing and testing everything, as so do others who use the interpreter. \$\endgroup\$
    – Dion
    Aug 17 '20 at 8:57
  • \$\begingroup\$ @JoKing - Thanks! @Dion - When I click on your link (or that of JoKing) in either Chrome or in Firefox, I get the 'MAWP version 1.1 (latest)' web page, but the 'code:' box is empty. In Chrome I can manually copy-paste the code into the box, and it then works fine when I click 'Run code', but it's difficult to get the code out of the link because many of the characters are represented with %s. FYI, I just tried to generate my own link (using the 'generate link' button after pasting-in your code), and this link also opens an empty 'code:' box. Hope this helps.... \$\endgroup\$ Aug 17 '20 at 15:57
  • \$\begingroup\$ @DominicvanEssen if it doesn't trouble you, would you mind and telling me two things: a) are the query's in the links empty b) does the dev console show any errors on loading and/or link generating? Thanks! \$\endgroup\$
    – Dion
    Aug 17 '20 at 16:00
  • \$\begingroup\$ @Dion - I'm not a developer so I'm rather out of my depth here, but I'll try to answer. Let me know if I haven't told you what you need to know. The link seems to contain the program (it ends with .../?code=481...b%5D&input=, but the program doesn't end-up in the 'code:' box. I don't really know what the 'dev console' is, but (in Chrome) I clicked on 'View>Developer>Developer tools' and selected the 'console' tab, and there are no errors displaying (either for loading or creating links). \$\endgroup\$ Aug 17 '20 at 16:11
4
\$\begingroup\$

V, 4 bytes

2i2i

Try it online!

Explanation:

2       " Two times:
 i      " Insert the following:
  2i    " The string '2i'

This is pretty straightforward. In fact, this almost works in regular vim. There is just one minor thing in the way: The string '2i' isn't inserted twice until you hit <esc>. In V, this is solved by implicitly ending every program with an <esc> (Really, that's an oversimplification, but it's close enough to the truth).

Old versions of V always added a newline to the output, which is why I didn't post this earlier. However, in commit b6c238d, this was fixed.

This answer works just because of luck. The approach doesn't extend well to general purpose quines/quine-variations. The shortest quine I'm aware of that can be trivially modified is

ñéÑ~"qpÿ

Try it online!

Explanation:

ñ           " Start recording into register 'q'
 éÑ         " Insert 'Ñ' (uppercase so that the recording doesn't stop here)
   ~        " Toggle the case the character under the cursor (the 'Ñ')
    "qp     " Paste the contents of register 'q'
       ÿ    " Stop recording and play it all back

The reason the ÿ is needed, is because it is implicitly added to the end of macros, a feature that is unfortunate for quines, but very convenient for golf.

The nice thing about this quine is that we can do almost anything inside of the recording and it is still valid since it will be pasted later anyway.

\$\endgroup\$
4
\$\begingroup\$

ShapeScript, 16 bytes

'"%r"@%"0?!"'0?!

Try it online!

Verification

$ shapescript quine.shape | diff -sq - quine.shape
Files - and quine.shape are identical

How it works

'       Push a string that, when evaluated, does the following.
  "%r"  Push this formatting string. %r gets replaced by a string
        representation of the corresponding argument.
  @     Swap the string that is being evaluated on top of the stack.
  %     Apply formatting to the string on top of the stack.
  "0?!" Push that string.
'
0?!     Push a copy of the previous string and evaluate it.

ShapeScript, 32 bytes

'"'"'"'1?3?+3*2?+@+@+@#"0?!"'0?!

This version does not use string formatting. It's not particularly short, but I find it rather interesting.

Try it online!

How it works

'"'     Push a double quote singleton string.
"'"     Push a single quote singleton string.
'       Push a string that, when evaluated, does the following:
  1?3?    Copy the second and fourth topmost stack items.
          This pushes a copy of the single, then the double quote.
  +3*     Concatenate both and repeat the result three times.
  2?+     Copy the third topmost stack item and append it to the string.
          We now have a string of the first seven characters of the source.
  @+      Swap with the string on the stack (the string that is being
          evaluated) and concatenate.
  @+      Swap with the original single quote and concatenate.
  @#      Swap with the original double quote and discard it.
  "0?!"   Push that string.
'
0?!     Push a copy of the above string and evaluate it.
\$\endgroup\$
4
\$\begingroup\$

C++, 117 bytes

#include<cstdio>
#define Q(S)char*q=#S;S
Q(int main(){printf("#include<cstdio>\n#define Q(S)char*q=#S;S\nQ(%s)",q);})

Try it online!

\$\endgroup\$
4
  • 1
    \$\begingroup\$ What compiler does this use? This does not appear to work on gcc. \$\endgroup\$
    – Wheat Wizard
    Jan 13 '17 at 15:26
  • \$\begingroup\$ It works on my gcc 4.9.2. \$\endgroup\$ Jan 13 '17 at 15:38
  • 2
    \$\begingroup\$ Ok. According to clang, this is not valid C++, since the return type of main() is missing. I fixed that now. \$\endgroup\$ Jan 13 '17 at 15:40
  • \$\begingroup\$ My version of gcc was 4.2.1 (I should update some time). Now that main has a return type it works. \$\endgroup\$
    – Wheat Wizard
    Jan 13 '17 at 15:47
4
\$\begingroup\$

Vyxal, 57 bytes

2996557859220556162530996767470:`0123456789+:`\\\`\τ+++τ+

Try it Online!

The big number at the front is the rest of the program encoded using the key 0123456789+:τ\ with a backtick (dammit markdown). The rest of the program constructs the key, decodes this, and concatenates the original number to the result.

\$\endgroup\$
4
\$\begingroup\$

Red, 21 bytes

do s: "prin{do }?? s"

Try it online!

Explanation

?? is usually used when debugging, but it's also great for quines. Take the following code:

s: "foo"
?? s

It outputs s: "foo". Let's see what happens when we combine this with a do:

do s: "?? s"

As expected, we get s: "?? s". Ignoring the do, it's pretty much already a quine. We can easily fix this by adding a prin{do } before the ?? s:

do s: "prin{do }?? s"
\$\endgroup\$
2
  • \$\begingroup\$ Is it alright if I bounty your first answer instead? \$\endgroup\$
    – Wezl
    Jun 9 at 21:01
  • \$\begingroup\$ @Wzl Ah, yes that's perfectly fine. \$\endgroup\$ Jun 9 at 22:30
4
\$\begingroup\$

Klein, 13 + 6 = 19 bytes

Martin Ender has made a shorter Quine here

+6 from the 000 topology and the -A flag, (also works in the 001 topology)

<:3+@+3:<"

Try it online!

Explanation

Like described in my earlier not so Quine the " character cannot be made with a string literal so we need to make it by doing math on a similar character, in this case the unit separator character for reasons described later. The difference between this Quine and earlier attempts is that this we can get around the restriction of having to read the string forwards by making the string itself a palindrome. This way reading backwards is the same as reading it forwards.

So when the program starts it passes through a unit separator, then hits < which turns it around, it goes through the " and pushes the entire line. :3+ turns makes a " out of the final unit separator and @ terminates the program causing it to print.

\$\endgroup\$
4
\$\begingroup\$

Vyxal D, 12 bytes

`q\`:Ė\`+`:Ė

Try it Online!

What differences this from the other quine is an eval quine so is easily payload-capable - that is, all the processing code you need can go after the + and only needs to be iterated once.

Will be 9 bytes once parsing bugs get fixed.

`        `   # String of code to be executed
 q           # Quotify / uneval
  \`:Ė\`+    # Append a `:Ė`
          :  # Duplicate
           Ė # Run on itself
\$\endgroup\$
4
+100
\$\begingroup\$

Javastack, 64 bytes

"34 char swap add 2 repeat print"34 char swap add 2 repeat print

No TIO yet, watch this space!

Javastack aims to combine the verbosity of Java with the stack-based paradigm to create a truly horrible programming experience. I'm planning to make up for the verbosity with a truly immense library of functions, but it's all a work in progress.

Javastack doesn't have any way to get the character " aside from 34 char, so that's what we start with. We prepend it to the string currently on the stack (which is part of the code) with swap add, double it with 2 repeat, and print it, resulting in the source code.

-12 thanks to Aaron Miller - outgolfing me in my own language!

\$\endgroup\$
7
  • 4
    \$\begingroup\$ Doesn't look too verbose compared to Forth or Factor :P \$\endgroup\$
    – Bubbler
    Aug 5 at 9:06
  • 1
    \$\begingroup\$ Not that Java if everything doesn't have to be inside a class, you don't have to deal with any qualified names, and you don't have to declare the types of... stack positions? I'm going mad even trying to think about that last point \$\endgroup\$ Aug 5 at 9:08
  • 3
    \$\begingroup\$ @UnrelatedString Ooh, good idea! \$\endgroup\$
    – emanresu A
    Aug 5 at 9:09
  • 1
    \$\begingroup\$ "I'm planning to make up for the verbosity with a truly immense library of functions." Sounds more like Factor than Java to me :P \$\endgroup\$
    – user
    Aug 5 at 15:06
  • \$\begingroup\$ You can get rid of the space before each 34 char for 74 bytes: "34 char swap add duplicate add print"34 char swap add duplicate add print \$\endgroup\$ Aug 5 at 16:01
3
\$\begingroup\$

(ucb)logo - 28 chars

to q
po "q
pr "q
bye
end

q
\$\endgroup\$
3
\$\begingroup\$

Mathematica 17 19

ToString[#0][] & []
\$\endgroup\$
1
  • \$\begingroup\$ Why Community Wiki? \$\endgroup\$
    – MD XF
    Jun 12 '17 at 23:47
3
\$\begingroup\$

Pyth, 11 bytes

jN*2]"jN*2]

Surprised this hadn't been posted yet :P

\$\endgroup\$
3
\$\begingroup\$

Brachylog, 3 bytes

@Qw

This expects no input or output, i.e. brachylog_main(_,_)..

@Q is the string "@Qw", and w is the write predicate.

A 34 bytes quine without a specific built-in for quines

"~c~s~cS:[34:S:34]rw"S:[34:S:34]rw

This is a basic quine strategy applied to this language:

"~c~s~cS:[34:S:34]rw"              § Create a string containing the source code
                                   § ~c~s~c gets replaced by the arguments of predicate w
                                   § in their respective order in the list
                                   § ~c prints the arg as a char code, ~s as a string
                     S             § Call this string S
                      :[34:S:34]rw § Write the format S to the output with args " (34),
                                   § S and " replacing ~c, ~s and ~c respectively
\$\endgroup\$
3
\$\begingroup\$

Squeak Smalltalk - 91!

I just translated my Factor answer:

[:b|b value:b]value:[:b|Transcript show: '[:b|b value:b]value:[:b|' , b sourceString , ']']

Just DoIt! in a Workspace, prints itself to the Transcript.

Blocks don't have a reference to self, so i used another block as a combinator.

I'm sure there MUST be a shorter Smalltalk quine! After all it's Small-talk :P

No cheating -- that means that you can't just read the source file and print it.

At first I thought BlockClosure>>sourceString could be cheating as stated in the question, but looking at the Squeak implementation, doesn't seem to be reading the sources file1, but decompiling the block.

1: Smalltalk's image usually saves compiled code, and links to an external file with the original source.

\$\endgroup\$
10
  • \$\begingroup\$ It's cheating if b is your whole program. However, if b is a function or string literal, it's fine. \$\endgroup\$
    – wizzwizz4
    Feb 14 '16 at 9:05
  • \$\begingroup\$ @wizzwizz4 Thanks for the clarification! \$\endgroup\$
    – fede s.
    Feb 14 '16 at 21:56
  • \$\begingroup\$ Yeah sourceString looks like "read[ing] the source file and print[ing] it". \$\endgroup\$ Feb 14 '16 at 22:34
  • 1
    \$\begingroup\$ The second largest program I've seen. 91! = 1.352002e+140 :P \$\endgroup\$
    – user48538
    May 16 '16 at 20:29
  • 1
    \$\begingroup\$ @fedes. probably needs more jQuery \$\endgroup\$
    – cat
    May 17 '16 at 23:23
3
\$\begingroup\$

Go, 115 bytes

package main;import."fmt";func main(){s:="package main;import.\"fmt\";func main(){s:=%q;Printf(s,s);}";Printf(s,s)}

Blowing the previous Go record out of the water!

\$\endgroup\$
1
  • \$\begingroup\$ Nice job, there! \$\endgroup\$ Mar 23 '16 at 17:53
3
\$\begingroup\$

Ouroboros, 30 bytes

;T...!59*\1=33*++o.9=\1=2*+(1"

The T should be replaced with a literal tab character.

About Ouroboros

Each line of an Ouroboros program represents a snake eating its own tail, with the beginning of the line being the head and the end being the tail. The only control flow operations are commands to eat or regurgitate characters of the tail. When the instruction pointer reaches the last part of the line that hasn't been eaten, it loops back to the beginning. If the instruction pointer is swallowed, execution halts.

While Ouroboros has some similarities to 2D languages such as ><>, its limited control flow options presented a challenge for quine construction. The only way to skip an instruction is to put it near the end and swallow it--which means instructions near the beginning basically can't be skipped. It took some experimenting before I found a quine structure that worked.

Explanation

The core idea is similar to a ><> or Befunge quine: with a wrapping IP, a single " mark can be used to stringify the code on one pass and execute it on another. Ouroboros automatically pushes strings to the stack in reverse order, which simplifies things. However, we have to put the quotation mark at the end so we can swallow it to avoid pushing the string multiple times. That means that the code must be executed first, then the string pushed, and then the code executed again until the output is complete.

On every pass, the code does two main things: output a character and swallow 0 or more characters of code.

...!59*\1=33*++o

On the first pass, the stack is empty and treated as zero. Logically negating and multiplying by 59 gives the character code for ;, the first character of the quine. On the final pass, the 1 that was pushed right before the string (at the very end of the code) is encountered, to which we add 33 to turn it into 34, the closing ". On other passes, the character code is output unchanged. In pseudocode: output (!top)*59 + (top==1)*33 + top

.9=\1=2*+(

There are two passes on which code needs to be swallowed. On the first pass after we push the string (when we print the tab) the quotation mark has to go; and on the last pass (after we've processed the whole string and the 1 is left on the stack) two more characters are eaten to swallow the instruction pointer and end the program. On every other pass, don't eat anything. In pseudocode: swallow (top==9)+(top==1)*2

One problem remains: since we output the first character of code on the initial pass, we have to drop it (;) immediately after pushing the string so it won't be output a second time. But we don't want to drop anything on subsequent passes. Fortunately, at the end of each iteration we push another 1 to the stack, which is immediately dropped at the beginning of the next pass.

Try it out

// Define Stack class
function Stack() {
  this.stack = [];
  this.length = 0;
}
Stack.prototype.push = function(item) {
  this.stack.push(item);
  this.length++;
}
Stack.prototype.pop = function() {
  var result = 0;
  if (this.length > 0) {
    result = this.stack.pop();
    this.length--;
  }
  return result;
}
Stack.prototype.top = function() {
  var result = 0;
  if (this.length > 0) {
    result = this.stack[this.length - 1];
  }
  return result;
}
Stack.prototype.toString = function() {
  return "" + this.stack;
}

// Define Snake class
function Snake(code) {
  this.code = code;
  this.length = this.code.length;
  this.ip = 0;
  this.ownStack = new Stack();
  this.currStack = this.ownStack;
  this.alive = true;
  this.wait = 0;
  this.partialString = this.partialNumber = null;
}
Snake.prototype.step = function() {
  if (!this.alive) {
    return null;
  }
  if (this.wait > 0) {
    this.wait--;
    return null;
  }
  var instruction = this.code.charAt(this.ip);
  var output = null;
  console.log("Executing instruction " + instruction);
  if (this.partialString !== null) {
    // We're in the middle of a double-quoted string
    if (instruction == '"') {
      // Close the string and push its character codes in reverse order
      for (var i = this.partialString.length - 1; i >= 0; i--) {
        this.currStack.push(this.partialString.charCodeAt(i));
      }
      this.partialString = null;
    } else {
      this.partialString += instruction;
    }
  } else if (instruction == '"') {
    this.partialString = "";
  } else if ("0" <= instruction && instruction <= "9") {
    if (this.partialNumber !== null) {
      this.partialNumber = this.partialNumber + instruction;  // NB: concatenation!
    } else {
      this.partialNumber = instruction;
    }
    next = this.code.charAt((this.ip + 1) % this.length);
    if (next < "0" || "9" < next) {
      // Next instruction is non-numeric, so end number and push it
      this.currStack.push(+this.partialNumber);
      this.partialNumber = null;
    }
  } else if ("a" <= instruction && instruction <= "f") {
    // a-f push numbers 10 through 15
    var value = instruction.charCodeAt(0) - 87;
    this.currStack.push(value);
  } else if (instruction == "$") {
    // Toggle the current stack
    if (this.currStack === this.ownStack) {
      this.currStack = this.program.sharedStack;
    } else {
      this.currStack = this.ownStack;
    }
  } else if (instruction == "s") {
    this.currStack = this.ownStack;
  } else if (instruction == "S") {
    this.currStack = this.program.sharedStack;
  } else if (instruction == "l") {
    this.currStack.push(this.ownStack.length);
  } else if (instruction == "L") {
    this.currStack.push(this.program.sharedStack.length);
  } else if (instruction == ".") {
    var item = this.currStack.pop();
    this.currStack.push(item);
    this.currStack.push(item);
  } else if (instruction == "m") {
    var item = this.ownStack.pop();
    this.program.sharedStack.push(item);
  } else if (instruction == "M") {
    var item = this.program.sharedStack.pop();
    this.ownStack.push(item);
  } else if (instruction == "y") {
    var item = this.ownStack.top();
    this.program.sharedStack.push(item);
  } else if (instruction == "Y") {
    var item = this.program.sharedStack.top();
    this.ownStack.push(item);
  } else if (instruction == "\\") {
    var top = this.currStack.pop();
    var next = this.currStack.pop()
    this.currStack.push(top);
    this.currStack.push(next);
  } else if (instruction == "@") {
    var c = this.currStack.pop();
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(c);
    this.currStack.push(a);
    this.currStack.push(b);
  } else if (instruction == ";") {
    this.currStack.pop();
  } else if (instruction == "+") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(a + b);
  } else if (instruction == "-") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(a - b);
  } else if (instruction == "*") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(a * b);
  } else if (instruction == "/") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(a / b);
  } else if (instruction == "%") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(a % b);
  } else if (instruction == "_") {
    this.currStack.push(-this.currStack.pop());
  } else if (instruction == "I") {
    var value = this.currStack.pop();
    if (value < 0) {
      this.currStack.push(Math.ceil(value));
    } else {
      this.currStack.push(Math.floor(value));
    }
  } else if (instruction == ">") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(+(a > b));
  } else if (instruction == "<") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(+(a < b));
  } else if (instruction == "=") {
    var b = this.currStack.pop();
    var a = this.currStack.pop();
    this.currStack.push(+(a == b));
  } else if (instruction == "!") {
    this.currStack.push(+ !this.currStack.pop());
  } else if (instruction == "?") {
    this.currStack.push(Math.random());
  } else if (instruction == "n") {
    output = "" + this.currStack.pop();
  } else if (instruction == "o") {
    output = String.fromCharCode(this.currStack.pop());
  } else if (instruction == "r") {
    var input = this.program.io.getNumber();
    this.currStack.push(input);
  } else if (instruction == "i") {
    var input = this.program.io.getChar();
    this.currStack.push(input);
  } else if (instruction == "(") {
    this.length -= Math.floor(this.currStack.pop());
    this.length = Math.max(this.length, 0);
  } else if (instruction == ")") {
    this.length += Math.floor(this.currStack.pop());
    this.length = Math.min(this.length, this.code.length);
  } else if (instruction == "w") {
    this.wait = this.currStack.pop();
  }
  // Any unrecognized character is a no-op
  if (this.ip >= this.length) {
    // We've swallowed the IP, so this snake dies
    this.alive = false;
    this.program.snakesLiving--;
  } else {
    // Increment IP and loop if appropriate
    this.ip = (this.ip + 1) % this.length;
  }
  return output;
}
Snake.prototype.getHighlightedCode = function() {
  var result = "";
  for (var i = 0; i < this.code.length; i++) {
    if (i == this.length) {
      result += '<span class="swallowedCode">';
    }
    if (i == this.ip) {
      if (this.wait > 0) {
        result += '<span class="nextActiveToken">';
      } else {
        result += '<span class="activeToken">';
      }
      result += escapeEntities(this.code.charAt(i)) + '</span>';
    } else {
      result += escapeEntities(this.code.charAt(i));
    }
  }
  if (this.length < this.code.length) {
    result += '</span>';
  }
  return result;
}

// Define Program class
function Program(source, speed, io) {
  this.sharedStack = new Stack();
  this.snakes = source.split(/\r?\n/).map(function(snakeCode) {
    var snake = new Snake(snakeCode);
    snake.program = this;
    snake.sharedStack = this.sharedStack;
    return snake;
  }.bind(this));
  this.snakesLiving = this.snakes.length;
  this.io = io;
  this.speed = speed || 10;
  this.halting = false;
}
Program.prototype.run = function() {
  this.step();
  if (this.snakesLiving) {
    this.timeout = window.setTimeout(this.run.bind(this), 1000 / this.speed);
  }
}
Program.prototype.step = function() {
   for (var s = 0; s < this.snakes.length; s++) {
    var output = this.snakes[s].step();
    if (output) {
      this.io.print(output);
    }
  }
  this.io.displaySource(this.snakes.map(function (snake) {
      return snake.getHighlightedCode();
    }).join("<br>"));
 }
Program.prototype.halt = function() {
  window.clearTimeout(this.timeout);
}

var ioFunctions = {
  print: function (item) {
    var stdout = document.getElementById('stdout');
    stdout.value += "" + item;
  },
  getChar: function () {
    if (inputData) {
      var inputChar = inputData[0];
      inputData = inputData.slice(1);
      result = inputChar.charCodeAt(0);
    } else {
      result = -1;
    }
    var stdinDisplay = document.getElementById('stdin-display');
    stdinDisplay.innerHTML = escapeEntities(inputData);
    return result;
  },
  getNumber: function () {
    while (inputData && (inputData[0] < "0" || "9" < inputData[0])) {
      inputData = inputData.slice(1);
    }
    if (inputData) {
      var inputNumber = inputData.match(/\d+/)[0];
      inputData = inputData.slice(inputNumber.length);
      result = +inputNumber;
    } else {
      result = -1;
    }
    var stdinDisplay = document.getElementById('stdin-display');
    stdinDisplay.innerHTML = escapeEntities(inputData);
    return result;
  },
  displaySource: function (formattedCode) {
    var sourceDisplay = document.getElementById('source-display');
    sourceDisplay.innerHTML = formattedCode;
  }
};
var program = null;
var inputData = null;
function showEditor() {
  var source = document.getElementById('source'),
    sourceDisplayWrapper = document.getElementById('source-display-wrapper'),
    stdin = document.getElementById('stdin'),
    stdinDisplayWrapper = document.getElementById('stdin-display-wrapper');
  
  source.style.display = "block";
  stdin.style.display = "block";
  sourceDisplayWrapper.style.display = "none";
  stdinDisplayWrapper.style.display = "none";
  
  source.focus();
}
function hideEditor() {
  var source = document.getElementById('source'),
    sourceDisplay = document.getElementById('source-display'),
    sourceDisplayWrapper = document.getElementById('source-display-wrapper'),
    stdin = document.getElementById('stdin'),
    stdinDisplay = document.getElementById('stdin-display'),
    stdinDisplayWrapper = document.getElementById('stdin-display-wrapper');
  
  source.style.display = "none";
  stdin.style.display = "none";
  sourceDisplayWrapper.style.display = "block";
  stdinDisplayWrapper.style.display = "block";
  
  var sourceHeight = getComputedStyle(source).height,
    stdinHeight = getComputedStyle(stdin).height;
  sourceDisplayWrapper.style.minHeight = sourceHeight;
  sourceDisplayWrapper.style.maxHeight = sourceHeight;
  stdinDisplayWrapper.style.minHeight = stdinHeight;
  stdinDisplayWrapper.style.maxHeight = stdinHeight;
  sourceDisplay.textContent = source.value;
  stdinDisplay.textContent = stdin.value;
}
function escapeEntities(input) {
  return input.replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
}
function resetProgram() {
  var stdout = document.getElementById('stdout');
  stdout.value = null;
  if (program !== null) {
    program.halt();
  }
  program = null;
  inputData = null;
  showEditor();
}
function initProgram() {
  var source = document.getElementById('source'),
    stepsPerSecond = document.getElementById('steps-per-second'),
    stdin = document.getElementById('stdin');
  program = new Program(source.value, +stepsPerSecond.innerHTML, ioFunctions);
  hideEditor();
  inputData = stdin.value;
}
function runBtnClick() {
  if (program === null || program.snakesLiving == 0) {
    resetProgram();
    initProgram();
  } else {
    program.halt();
    var stepsPerSecond = document.getElementById('steps-per-second');
    program.speed = +stepsPerSecond.innerHTML;
  }
  program.run();
}
function stepBtnClick() {
  if (program === null) {
    initProgram();
  } else {
    program.halt();
  }
  program.step();
}
function sourceDisplayClick() {
  resetProgram();
}
.container {
    width: 100%;
}
.so-box {
    font-family:'Helvetica Neue', Arial, sans-serif;
    font-weight: bold;
    color: #fff;
    text-align: center;
    padding: .3em .7em;
    font-size: 1em;
    line-height: 1.1;
    border: 1px solid #c47b07;
    -webkit-box-shadow: 0 2px 2px rgba(0, 0, 0, 0.3), 0 2px 0 rgba(255, 255, 255, 0.15) inset;
    text-shadow: 0 0 2px rgba(0, 0, 0, 0.5);
    background: #f88912;
    box-shadow: 0 2px 2px rgba(0, 0, 0, 0.3), 0 2px 0 rgba(255, 255, 255, 0.15) inset;
}
.control {
    display: inline-block;
    border-radius: 6px;
    float: left;
    margin-right: 25px;
    cursor: pointer;
}
.option {
    padding: 10px 20px;
    margin-right: 25px;
    float: left;
}
h1 {
    text-align: center;
    font-family: Georgia, 'Times New Roman', serif;
}
a {
    text-decoration: none;
}
input, textarea {
    box-sizing: border-box;
}
textarea {
    display: block;
    white-space: pre;
    overflow: auto;
    height: 50px;
    width: 100%;
    max-width: 100%;
    min-height: 25px;
}
span[contenteditable] {
    padding: 2px 6px;
    background: #cc7801;
    color: #fff;
}
#stdout-container, #stdin-container {
    height: auto;
    padding: 6px 0;
}
#reset {
    float: right;
}
#source-display-wrapper , #stdin-display-wrapper{
    display: none;
    width: 100%;
    height: 100%;
    overflow: auto;
    border: 1px solid black;
    box-sizing: border-box;
}
#source-display , #stdin-display{
    font-family: monospace;
    white-space: pre;
    padding: 2px;
}
.activeToken {
    background: #f93;
}
.nextActiveToken {
    background: #bbb;
}
.swallowedCode{
    color: #999;
}
.clearfix:after {
    content:".";
    display: block;
    height: 0;
    clear: both;
    visibility: hidden;
}
.clearfix {
    display: inline-block;
}
* html .clearfix {
    height: 1%;
}
.clearfix {
    display: block;
}
<!--
Designed and written 2015 by D. Loscutoff
Much of the HTML and CSS was taken from this Befunge interpreter by Ingo Bürk: http://codegolf.stackexchange.com/a/40331/16766
-->
<div class="container">
<textarea id="source" placeholder="Enter your program here" wrap="off">;	...!59*\1=33*++o.9=\1=2*+(1"</textarea>
<div id="source-display-wrapper" onclick="sourceDisplayClick()"><div id="source-display"></div></div></div><div id="stdin-container" class="container">
<textarea id="stdin" placeholder="Input" wrap="off"></textarea>
<div id="stdin-display-wrapper" onclick="stdinDisplayClick()"><div id="stdin-display"></div></div></div><div id="controls-container" class="container clearfix"><input type="button" id="run" class="control so-box" value="Run" onclick="runBtnClick()" /><input type="button" id="pause" class="control so-box" value="Pause" onclick="program.halt()" /><input type="button" id="step" class="control so-box" value="Step" onclick="stepBtnClick()" /><input type="button" id="reset" class="control so-box" value="Reset" onclick="resetProgram()" /></div><div id="stdout-container" class="container"><textarea id="stdout" placeholder="Output" wrap="off" readonly></textarea></div><div id="options-container" class="container"><div class="option so-box">Steps per Second:
<span id="steps-per-second" contenteditable>20</span></div></div>

\$\endgroup\$
3
\$\begingroup\$

R, 73 bytes (incl. tabs and newlines)

(f=function()
{
    cat("(f=function()\n")
    print(body(f))
    cat(")()")
}
)()

Shorter, less interesting quines are possible: function()1 is 11 bytes. + (1 byte) is an arguable quine, since the command prompt for an unfinished line is a plus sign by default, and + on its own counts as an unfinished line.

\$\endgroup\$
5
  • \$\begingroup\$ It is necessary to format exactly this way (can't remove tabs or replace newline with ";"), otherwise the output will not exactly match the input. \$\endgroup\$
    – JDL
    Aug 25 '16 at 14:17
  • \$\begingroup\$ A more trivial example is function()1 (11 bytes) but that's kinda boring... \$\endgroup\$
    – JDL
    Aug 26 '16 at 14:06
  • 2
    \$\begingroup\$ Your 14 bytes solution is not easy to find. And I don't find it boring at all! Suggestion: keep the 73 solution but list this solution as 14 bytes one so it found more easily using the leaderboard. \$\endgroup\$
    – JayCe
    May 16 '18 at 17:56
  • \$\begingroup\$ I may be misreading some details of how programs are defined in R, but I think list() is a shorter trivial solution? I can't do command-line verification, but it certainly plays interactively and on TIO (though you might argue a newline is needed for the latter) Try it online! \$\endgroup\$ Jan 31 '19 at 15:37
  • \$\begingroup\$ yes, list() (and numeric(0) and friends) are all quines in R. \$\endgroup\$
    – JDL
    Feb 1 '19 at 8:57
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