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Your task is to create the shortest infinite loop!

The point of this challenge is to create an infinite loop producing no output, unlike its possible duplicate. The reason to this is because the code might be shorter if no output is given.

Rules

  • Each submission must be a full program.
  • You must create the shortest infinite loop.
  • Even if your program runs out of memory eventually, it is still accepted as long as it is running the whole time from the start to when it runs out of memory. Also when it runs out of memory, it should still not print anything to STDERR.
  • The program must take no input (however, reading from a file is allowed), and should not print anything to STDOUT. Output to a file is also forbidden.
  • The program must not write anything to STDERR.
  • Feel free to use a language (or language version) even if it's newer than this challenge. -Note that there must be an interpreter so the submission can be tested. It is allowed (and even encouraged) to write this interpreter yourself for a previously unimplemented language. :D
  • Submissions are scored in bytes, in an appropriate (pre-existing) encoding, usually (but not necessarily) UTF-8. Some languages, like Folders, are a bit tricky to score - if in doubt, please ask on Meta.
  • This is not about finding the language with the shortest infinite loop program. This is about finding the shortest infinite loop program in every language. Therefore, I will not accept an answer.
  • If your language of choice is a trivial variant of another (potentially more popular) language which already has an answer (think BASIC or SQL dialects, Unix shells or trivial Brainf**k-derivatives like Alphuck), consider adding a note to the existing answer that the same or a very similar solution is also the shortest in the other language.
  • There should be a website such as Wikipedia, Esolangs, or GitHub for the language. For example, if the language is CJam, then one could link to the site in the header like #[CJam](http://sourceforge.net/p/cjam/wiki/Home/), X bytes.
  • Standard loopholes are not allowed.

(I have taken some of these rules from Martin Büttner's "Hello World" challenge)


Please feel free to post in the comments to tell me how this challenge could be improved.

Catalogue

This is a Stack Snippet which generates both an alphabetical catalogue of the used languages, and an overall leaderboard. To make sure your answer shows up, please start it with this Markdown header:

# Language name, X bytes

Obviously replacing Language name and X bytes with the proper items. If you want to link to the languages' website, use this template, as posted above:

#[Language name](http://link.to/the/language), X bytes

Now, finally, here's the snippet: (Try pressing "Full page" for a better view.)

var QUESTION_ID=59347;var ANSWER_FILTER="!t)IWYnsLAZle2tQ3KqrVveCRJfxcRLe";var COMMENT_FILTER="!)Q2B_A2kjfAiU78X(md6BoYk";var OVERRIDE_USER=41805;var answers=[],answers_hash,answer_ids,answer_page=1,more_answers=true,comment_page;function answersUrl(index){return"//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"//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:true,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=false;comment_page=1;getComments()}})}function getComments(){jQuery.ajax({url:commentUrl(comment_page++,answer_ids),method:"get",dataType:"jsonp",crossDomain:true,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=/<h\d>\s*([^\n,<]*(?:<(?:[^\n>]*>[^\n<]*<\/[^\n>]*>)[^\n,<]*)*),.*?(\d+)(?=[^\n\d<>]*(?:<(?:s>[^\n<>]*<\/s>|[^\n<>]+>)[^\n\d<>]*)*<\/h\d>)/;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,});else console.log(body)});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('<a>'+lang+'</a>').text();languages[lang]=languages[lang]||{lang:a.language,lang_raw:lang,user:a.user,size:a.size,link:a.link}});var langs=[];for(var lang in languages)if(languages.hasOwnProperty(lang))langs.push(languages[lang]);langs.sort(function(a,b){if(a.lang_raw.toLowerCase()>b.lang_raw.toLowerCase())return 1;if(a.lang_raw.toLowerCase()<b.lang_raw.toLowerCase())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;width:500px;float:left}#language-list{padding:10px;padding-right:40px;width:500px;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="//cdn.sstatic.net/codegolf/all.css?v=83c949450c8b"> <div id="language-list"> <h2>Shortest Solution 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>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr> </tbody> </table> <table style="display: none"> <tbody id="language-template"> <tr><td>{{LANGUAGE}}</td><td>{{NAME}}</td><td>{{SIZE}}</td><td><a href="{{LINK}}">Link</a></td></tr> </tbody> </table>

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  • 46
    \$\begingroup\$ I've got to start posting programs with a negative byte count to beat all these empty files! \$\endgroup\$ – CJ Dennis Oct 3 '15 at 4:32
  • 3
    \$\begingroup\$ This challenge is interesting because it brings out lots of 0 byte languages (some of which are NOT esolangs). FWIW, most declarative languages have an implicit infinite loop because declarative languages don't have loops in their syntax (they assume they're running in an infinite loop). Ladder diagrams are perhaps among the oldest such languages. Then you have the Instruction Language (IL), a sort of assembly for PLCs that also assume an infinite loop. ILs, like assembly are different between manufacturers \$\endgroup\$ – slebetman Oct 5 '15 at 9:36
  • \$\begingroup\$ Are programs that read and execute their own source code allowed, or does file I/O break the "must take no input" rule? \$\endgroup\$ – ThisSuitIsBlackNot Oct 6 '15 at 13:05
  • 1
    \$\begingroup\$ @ThisSuitIsBlackNot Yes, file input is allowed. \$\endgroup\$ – user41805 Oct 6 '15 at 16:47
  • \$\begingroup\$ Can you print "", an empty string? \$\endgroup\$ – OldBunny2800 Mar 7 '16 at 23:39

536 Answers 536

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1
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Ceylon, 30 29 bytes

This is an eternal loop (which also will not run out of memory or stack or something), 30 bytes:

shared void l(){while(true){}}

This can be golfed down one more byte to 29:

shared void l(){while(1<2){}}

In the Ceylon web runner you have to remove the function wrapper, getting this 12 byte snipped:

while(1<2){}

(I had to kill my Chromium window when trying this.)

This eternal recursion will quickly run out of stack space (about 1024 calls on my JVM implementation, with a StackOverflowError), 22 bytes:

shared void r() {r();}

I wouldn't consider this a valid solution.

Note that the for-loop (which is the shortest endless loop in Java) in Ceylon can only loop over an iterable, and all ways of constructing an infinite iterable are longer. Here is one example (38 bytes):

shared void f(){for(x in{1}.cycled){}}
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1
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BSM, 1 byte

 

A single space character. Had to use some brute-forcing for this... After about 125 cycles, it loops between the states 55, EF, B1, 5A, AD, B2, D9, DC, 9C, 13, 19, and F9.

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1
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Enigma-2D, 2 bytes

RL

The IP alternates between moving rightwards and leftwards.

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1
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MarioLANG(4 Bytes)

><
==
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2
  • 1
    \$\begingroup\$ There is already a shorter solution in the same language. \$\endgroup\$ – user45941 Jul 2 '16 at 2:33
  • \$\begingroup\$ This is 5 bytes, not 4. \$\endgroup\$ – Makonede Dec 18 '20 at 19:17
1
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Nim, 16 bytes

while on:discard

on is an alias for true. Nim disallows expressions that aren't explicitly discarded, so we just discard nothing.

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1
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Logicode, 24 bytes

circ r(a)->r(a)
out r(1)

Logicode is a new language that I made recently. It only consists of the basic logic gates AND, OR and NOT.

It also contains some nifty stuff like conditionals, make-your-own circuits, and output.

Basically, the first line declares a new circuit, r, with an argument a, and declares the output of the circuit to be r(a). This basically results in an infinite loop.

out r(1) outputs r(1).

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Ru, 4 bytes

¿Ϟ{}

¿ call a function while koppa is not 0/nil/false. But since Ϟ also return its argument, it's possible to chain ¿ and Ϟ.

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1
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Racket 18 bytes

(λ()(let g()(g)))
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1
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Emotinomicon, (2 chars) 6 bytes

ℹ⏩

I cleverly chose the character for 3 bytes instead of 4. Explanation:

ℹ⏩ explanation
ℹ  push the imaginary unit to the stack
 ⏩ close loop

It works, because 1) has got a value (i) 2) can't find a .

To test the code, do the following:

  1. Open the interpreter.
  2. Clean the box and then put a 😷 in it (not part of the code, just in case you have a dirty output stream).
  3. Paste the code after that one-big-toothed strange guy.
  4. Click on "generate explanation". Watch the steps done there (also, no mono-spacing issues).
  5. Click on "submit". Warning: the code will run after this step!
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  • \$\begingroup\$ You're shown in the Leaderboard as 2 bytes. Also why non competing? \$\endgroup\$ – Roman Gräf Oct 16 '16 at 8:07
  • \$\begingroup\$ @RomanGräf The language was made in December 2015, this challenge is from October 2015. \$\endgroup\$ – Erik the Outgolfer Oct 16 '16 at 8:16
  • \$\begingroup\$ WHY is this question still active???? \$\endgroup\$ – Roman Gräf Oct 16 '16 at 8:19
  • \$\begingroup\$ @RomanGräf Because I just edited my answer. Dunno why I put non-competing in there, though... \$\endgroup\$ – Erik the Outgolfer Oct 16 '16 at 8:20
1
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D2, 3 bytes

+[]

Same as Brainfuck

More interesting version using the preprocessor (the code is actually never executed because the infinite loop is in the preprocessor):

(@a)a@a

Simple recursive macro

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1
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Lithp, 40 bytes

((platform ext)(invoke (stdin) resume))

There are presently no loop constructs in my language. Instead, we tell NodeJS (in which Lithp is implemented) to resume the process.stdin stream. We haven't setup a handler, but the process will never exit.

In fact, you have to send a kill message to abort the application.

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PHP, 9 bytes

back to basic:

L:goto L;

^_^

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Clojure, 21 10 bytes

(#(recur))

After posting a question of meta regarding what's considered a full program in Clojure, it seems that the above is acceptable. If you paste it in an empty source file, it will run.

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1
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TI-83 Hex Assembly, 3 bytes

PROGRAM:L
:AsmPrgm
:C3959D

Run it with Asm(prgmL). Jumps to itself over and over. The only way to stop the program is to physically remove the batteries from the calculator. I count each pair of hex digits as one byte.

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1
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Pushy, 2 1 bytes

[

Try it online!

Hah, [ is just an infinite loop, that's its only function if you see here.

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1
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FALSE, 6 bytes

[1][]#

This is a while loop (#) with an empty body function ([]) and a condition function that always yields a truthy value. It runs forever without yielding output.

Interpreter used.

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1
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Lithp, 27 bytes

 ((def x #::((next x)))(x))

Define a function, x, which uses tail recursion (via next) to call itself. Then call function x.

This program will never finish. You can't even CTRL+C out of it since keyboard input isn't handled in Node.js whilst in a while loop.

If one were to provide the -d flag to run.js, they would see the function calling itself over and over, never finishing nor running out of stack space.

This was a neat feature to get working in my language. Typically one would use some sort of logic flow to determine whether to return a value or tail recurse back into the current function (using next or recurse.)

The implementation of such tail recursion was fairly simple, but its implications in my functional language are great. My feature set is getting nearer and nearer to Erlang's every week. And that's fun.

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tinylisp, 13 bytes

((v(d f(q(L(f

Parenthesis autocompletion really helps!

We define a function f that calls itself using tail-call recursion. Functions in tinylisp are lists containing two elements: parameter list and expression. Here, our parameter list is L (which makes this a variadic function: L is bound to a list of all arguments) and our expression is (f) (calling the function with no arguments).

((v(d f(q(L(f))))))
         (L(f))      The function list
       (q      )     Quoted to prevent evaluation
   (d f         )    Define f to be that list
 (v              )   The d call returns the name f; evaluate it to get the function itself
(                 )  Call the function

Use Ctrl-C to halt execution.

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1
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uBASIC, 7 bytes

1GOTO1

Note trailing newline. Trivial BASIC variant.

Try it online!

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1
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Excel VBA, 7 Bytes

Do:Loop

Note: the above freezes Excel - the shortest Excel VBA loop that does not do this is Do:DoEvents:Loop (16 Bytes)

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1
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GNU Sed, 3 bytes

Unlike this answer by @Digital Trauma (which relies on bug #21250: sed: empty label for :/b/t commands), does only use documented Sed commands, in the same byte count.

Golfed

G 
D

Explained

G       #Append a newline to the contents of the pattern 
        #space, and then append the contents of the hold
        #space to that of the pattern space.

D       #Delete text in the pattern space up to the 
        #first newline, and restart cycle with the 
        #resultant pattern space, without reading a new 
        #line of input.
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1
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tcl, 7 bytes

vwait v

Explanation

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1
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Forte, 4 bytes

1REM

Without an END statement, Forte programs loop infinitely. The empty program is an error, so we leave a comment.

Try it online!

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1
  • \$\begingroup\$ Nice job understanding Forte (even if all you did was write 4 characters in it) \$\endgroup\$ – Esolanging Fruit Jul 10 '17 at 0:06
1
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OIL, 1 byte

6

TIO does not currently support OIL.

Explanation:

6 // Jump to cell A.
0 // Implicit 0.
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1
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Samau, 3 bytes

`xx

Explanation

`x      push the quoted function [x]
  x     execute it without popping it 

It works like the Mathematica program #0[]&[], but Samau doesn't have an iteration limit.

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1
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Lua and RBX.Lua, 14 bytes

while 1 do end

Pretty self explanatory. While 1 is true, it will iterate through the loop.

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1
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Decimal, 6 bytes

91D91D

Pretty simple:

91D   ; declare jump 1
91D   ; goto jump 1

Try it online! I mean, not exactly try it, but... you know what I mean.

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1
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Braingolf, 4 bytes

[1+]

Try it online!

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1
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Fission 2, 1 byte

R

Try it online!

Spawns an atom moving right, wraps on the end of the line, R simply sets the atom's direction to right after the program has started

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1
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Lean Mean Bean Machine, 3 bytes

O
~

Marble spawns at O, drops to ~, which teleports it back up to the top of the column.

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