Empty program

Task

Create the simplest possible program that is still considered "correct."

11l

An empty text file is a correct 11l program that does nothing.

360 Assembly

Return to caller <lang 360 Assembly> BR 14

        END</lang>

6502 Assembly

Commodore 64

<lang 6502asm>org $0801 ;start assembling at this address db $0E,$08,$0A,$00,$9E,$20,$28,$32,$30,$36,$34,$29,$00,$00,$00 ;required init code rts ;return to basic</lang>

Nintendo Entertainment System

Without an infinite loop the program counter will execute undefined behavior, depending on how "empty" bytes are padded. If we're generous and assume that empty bytes are padded with NOP, eventually the program counter will attempt to execute the interrupt vectors as executable code. If we assume that an "empty program" needs to not crash (even though you really can't tell the difference with nothing on screen), we need a way to "trap" the program counter.

<lang 6502asm>.org $8000 ;usually $8000 but it depends on the mapper. RESET: ;execution starts here JMP RESET

NMI: ;NMI can't happen if the screen is off. No need for RTI

IRQ: ;this will never occur without a CLI command.

.org $FFFA

all 6502 based hardware uses this section of memory to hold the addresses of interrupt routines
as well as the entry point.

dw NMI ;FFFA-FFFB dw RESET ;FFFC-FFFD ;this has to be defined or else the program counter will jump to an unknown location dw IRQ ;FFFE-FFFF</lang>

68000 Assembly

This mostly depends on the implementation, but JMP $ will typically suffice.

Works with: NEOGEO

After you get to the main program, you'll need to kick the watchdog every frame to prevent the BIOS from resetting the machine. This is done by writing any byte to memory address 0x00300001. Other than that, an endless loop will suffice (assuming you have a proper cartridge header and a vBlank routine that does nothing except check for bios vblank and return.)

<lang 68000devpac>forever: MOVE.B D0,$300001 JMP forever</lang>

8051 Assembly

Continuously loops. <lang asm>ORG RESET jmp $</lang>

8086 Assembly

16-Bit x86 for EXE Files

<lang asm>.model small ;.exe file .stack 1024 ;this value doesn't matter, I chose this arbitrarily .data

             ;not needed in an empty program

.code mov ax,4C00h int 21h ;exit this program and return to MS-DOS</lang>

32-Bit x86

However, if the program needs to exit with an exit code of zero:

<lang asm> segment .text

   global _start

_start:

   mov eax, 60
   xor edi, edi
   syscall
   end</lang>

AArch64 Assembly

Simulates system call exit(0). In AArch64, the system call number is passed via x8, and the syscall number for exit is 93. <lang ARM_Assembly>.text .global _start

_start:

       mov x0, #0
       mov x8, #93
       svc #0</lang>

ABAP

Note that the statement "start-of-selection." is implicitly added. This event block needs to be present in executable programs, it's comparable to the main function in other programming languages.

<lang ABAP> report z_empty_program. </lang>

Action!

Output:

Screenshot from Atari 8-bit computer

Ada

Works with: GCC version 4.1.2

<lang ada>procedure Empty is begin

  null;

end;</lang>

Agena

Actually nothing is valid code, too. <lang agena></lang>

Aime

The nil input is a valid program. <lang aime></lang>

ALGOL 60

<lang algol60>'BEGIN' 'END'</lang>

ALGOL 68

Brief form

BOLD form

ALGOL W

In Algol W, a blank statement is a valid statement and a program is a statement followed by a dot. Hence "." is the smallest valid program. <lang algolw>.</lang>

AmigaE

<lang amigae>PROC main() ENDPROC</lang>

AppleScript

An empty .scpt file is considered the smallest runnable code, but the following would also be acceptable. <lang applescript>return</lang>

Argile

The empty string or file are valid and do nothing. <lang Argile></lang>

ARM Assembly

GNU/Linux RaspberryPi

<lang ARM_Assembly>.text

   .global _start

_start:

   mov r0, #0
   mov r7, #1
   svc #0 </lang>

Game Boy Advance

The Nintendo logo is loaded from the cartridge, and the Game Boy Advance's firmware won't boot the game without it. So an empty program can't be run at all. Thus a minimum of a valid cartridge header is required for an empty program that the Game Boy Advance can actually run. The first four bytes of the cartridge header are an unconditional branch instruction to the program's start. Simply duplicate this instruction at that address and voila:

<lang ARM_Assembly>ProgramStart: b ProgramStart ;don't do this on a real game boy, you'll drain the batteries faster than usual.</lang>

Hardware interrupts will not occur if you never enable them, so there is no need to store the interrupt service procedure's address in address $03FFFFFC to prevent a crash. The Game Boy Advance has no "exit" SWI call (the closest is the undocumented hard reset) so this is as close as you can get.

ArnoldC

<lang ArnoldC>IT'S SHOWTIME YOU HAVE BEEN TERMINATED</lang>

Arturo

A completely empty script is a valid Arturo program.

AutoHotkey

An empty script would be enough. Adding "#Persistent" makes it persistent. <lang AutoHotkey>#Persistent</lang>

AutoIt

A single comment can be considered a valid program that does nothing. <lang AutoIt>;nothing</lang>

Avail

Avail files require a header block (that is generally omitted from the examples here). The shortest valid header would only include the module name, which can be reduced to 1 character, assuming the filename is set to match. For "a.avail", this gives the empty program: <lang Avail>Module "a" Body</lang> This can be further shortened by removing unambiguous whitespace to: <lang Avail>Module"a"Body</lang> For all practical purposes, this header is useless in any other program. It does not import the standard library "Avail" (or any alternatives), so it has access to no methods, types, or values. Here's a short program capable of output: <lang Avail>Module"a"Uses"Avail"Body Print:"!";</lang> Or with more traditional spacing: <lang Avail>Module "a" Uses "Avail" Body Print:"!";</lang> Note however that this output is only available as a compile-time side effect. A program defining a run-time entry point would include an Entries header section, or export its content for an entry point in another module to run.

AWK

The empty string (or file) is recognised as valid program that does nothing.

The program <lang awk> 1</lang> is the simplest useful program, equivalent to <lang awk>// {print}</lang> I.e. match every input-line, and print it.
Like the UNIX command 'cat', it prints every line of the files given as arguments, or (if no arguments are given) the standard input.

Axe

Most Axe examples omit the executable name, but it is shown in this example for completeness. <lang axe>:.PRGMNAME

</lang>

BASIC

Works with: QBASIC

Works with: Quick BASIC

Works with: FreeBASIC

Works with: uBasic/4tH

An empty file is a correct program. It won't be near empty as an executable file, though. <lang qbasic></lang>

Works with: ZX Spectrum Basic

On the ZX Spectrum, we can have a completely empty program with no lines. Here we attempt to run the empty program: <lang basic>RUN</lang>

0 OK, 0:1

Applesoft BASIC

Batch File

On Windows XP and older, an empty batch file is syntactically correct and does nothing. <lang dos></lang> But on Windows 7, an empty .bat file is not recognized and thus a character must exist in it. Some valid characters are : @ % <lang dos>:</lang>

BaCon

In BaCon an empty program is a valid program. <lang bacon></lang>

BASIC256

BBC BASIC

In BBC BASIC an empty program is syntactically correct. <lang bbcbasic></lang>

bc

An empty file is a valid program.

Beeswax

<lang beeswax>*</lang> (create 6 bees moving in all 6 cardinal directions) or <lang beeswax>\</lang> (create 2 bees moving in “northwest” and “southeast” directions) or <lang beeswax>_</lang> (create 2 bees moving left and right) or <lang beeswax>/</lang> (create 2 bees moving in “northeast” and “southwest” directions)

A valid beeswax program needs at least one of these bee spawning symbols, as a program without bees is not executable. All bees that step off the honeycomb (program area) are automatically deleted, and the program ends if no bees are left.

Befunge

The halt command @ is required because code wraps around. An empty file would be an infinite loop.

bootBASIC

BQN

An empty program in BQN produces an error. There must be at least one line which returns a value.

Any valid literal works to make a program run. The shortest way is to use a single digit, or a predefined constant, like π or ∞.

<lang bqn>∞</lang> Try It!

Bracmat

An empty file is a valid program. However you need to load it, which requires a statement. In a Linux terminal, you could do <lang bracmat>touch empty bracmat 'get$empty'</lang>

In DOS, you can do <lang dos>touch empty bracmat get$empty</lang>

If we drop the requirement that the shortest program is stored in a file, we can do <lang bash>bracmat </lang> (Linux) or <lang dos>bracmat ""</lang> (Windows)

If two quotes to demarcate an empty string are counted as bigger than a single undemarcated non-empty expression, we can do

 bracmat .

The dot is a binary operator. So the input consists of three nodes: the operator and its lhs and rhs, both empty strings in this case. If three nodes is too much, consider a slightly bigger glyph, such as the hyphen, which is a prefix, not a binary operator:

 bracmat -

You also can start Bracmat without arguments, in which case it will run in interactive mode. Now press the Enter key. You have just run the shortest valid Bracmat program.

Brainf***

Empty program

Note: this works as all non-instruction characters are considered comments. Alternatively, a zero-byte file also works.

Brlcad

Pressing enter from the mged prompt, just returns another prompt, so I suppose that is the smallest possible program. However, before we can draw anything we at least need to open a database: <lang mged>opendb empty.g y</lang>

C

Works with: C89

<lang c>main() {

 return 0;

}</lang>

As of C99 the return type is required, but the return statement is not.

Works with: C99

This is technically undefined behavior but on 8086 compatible processors 195 corresponds to the ret assembly instruction.

Works with: C on 8086 compatible processors

<lang c>const main = 195;</lang>

C#

As of C# 9.0, an empty text file is a correct C# program that does nothing.

C++

Works with: g++ version 4.8.1

Clean

<lang clean>module Empty

Start world = world</lang> Compile the project with No Console or No Return Type to suppress printing of the value of the world.

Clojure

An empty file is the simplest valid Clojure program.

CLU

This is the shortest program that actually produces a working executable (that does nothing).

<lang>start_up = proc () end start_up</lang>

Portable CLU will compile the empty file without complaint, but not produce an object file.

COBOL

Works with: OpenCOBOL version 2.0

CoffeeScript

Common Lisp

Component Pascal

BlackBox Component Builder; <lang oberon2> MODULE Main; END Main. </lang>

Computer/zero Assembly

The smallest legal program is a single Stop instruction. <lang czasm> STP</lang>

D

Dart

dc

An empty file is a valid program.

DCL

An empty file is a valid program.

Delphi

See Pascal

Dyalect

Dyalect is not very happy with a completely empty source code file, however a pair of curly brackets would do:

This program would evaluate and return "nil".

Déjà Vu

<lang dejavu></lang> Shortest module that works with !import: <lang dejavu>{}</lang>

E

The shortest possible program:

This is equivalent to: <lang e>null</lang>

eC

or <lang ec>class EmptyApp : Application {

   void Main()
   {

}</lang>

EchoLisp

EDSAC order code

The smallest program that will load and run without error. Apart from ZF, the 'stop' order, it consists solely of directives to the loader. <lang edsac>T64K [ set load point ] GK [ set base address ] ZF [ stop ] EZPF [ begin at load point ]</lang>

Egel

The smallest program contains nothing. <lang Egel> </lang>

EGL

General program <lang EGL> package programs;

program Empty_program type BasicProgram {} function main() end end </lang> Rich UI handler (but also without 'initialUI = [ ui ], onConstructionFunction = start' it would have been valid.)

package ruihandlers;

import com.ibm.egl.rui.widgets.Div;

handler Empty_program type RUIhandler {initialUI = [ ui ], onConstructionFunction = start}
	ui Div{};
	
	function start()
	end	
end

Eiffel

A file called root.e: <lang eiffel>class

   ROOT

create

   make

feature

   make
       do
          
       end

end</lang>

Elena

ELENA 4.x <lang elena>public program() { }</lang>

Elixir

Elm

<lang elm> --Language prints the text in " " import Html main =

Html.text"empty"

</lang>

Erlang

An empty module: <lang erlang>-module(empty).</lang> An empty Erlang script file (escript): <lang erlang>main(_) -> 1.</lang>

ERRE

<lang> PROGRAM EMPTY BEGIN END PROGRAM </lang>

eSQL

<lang sql>CREATE COMPUTE MODULE ESQL_Compute

 CREATE FUNCTION Main() RETURNS BOOLEAN
 BEGIN
   RETURN TRUE;
 END;

END MODULE;</lang>

Euphoria

F#

F# has an interactive mode and a compiled mode. The interactive interpreter will accept an empty file so the shortest valid program is an empty zero-length file with the .fsx extension. <lang fsharp></lang> An empty compiled program is: <lang fsharp>[<EntryPoint>] let main args = 0</lang>

Factor

<lang factor></lang> If you want to deploy a stand-alone application, that doesn't suffice though. Here's another version. <lang factor>IN: rosetta.empty

main ( -- ) ;

MAIN: main</lang>

Falcon

Prints an empty line.

>>

Prints nothing.

FALSE

Fantom

<lang fantom>class Main {

 public static Void main () {}

}</lang>

FBSL

An empty string is a valid FBSL script in both uncompiled and compiled form. It won't however produce any visible output on the screen. The minimum implementations for the user to see the result are presented below:

Console mode:

#APPTYPE CONSOLE PAUSE

Output:

Press any key to continue...

Graphics mode:

SHOW(ME) ' all FBSL scripts are #APPTYPE GUI on default BEGIN EVENTS END EVENTS

Output: GUI Form

Minimum empty Dynamic Assembler block:

DYNASM Foo() RET ; mandatory END DYNASM

Minimum empty Dynamic C block:

DYNC Foo() void main(void) { return; // optional } END DYNC

Fermat

Fish

Actually the shortest valid program is a space (not empty file!), which is an infinite loop, though. (It keeps looping around) <lang Fish> </lang> An empty program is invalid; the interpreter will give an error.
The shortest program that will actually finish is a ;, which will end the program immediately: <lang Fish>;</lang>

Forth

<lang forth></lang> For a Forth script to be used from a shell, you usually want the last command to be BYE in order to exit the interpreter when finished. <lang forth>bye</lang>

Fortran

FreeBASIC

A completely empty program compiles and runs fine: <lang freebasic></lang>

friendly interactive shell

Empty programs are valid, but are useless. <lang fishshell></lang>

Frink

Empty programs are valid. <lang frink></lang>

FunL

An empty text file is a valid FunL program that does nothing. <lang funl></lang>

Futhark

Any Futhark program must have a main function. Alternatively, a Futhark library can be an empty file.

FutureBasic

Why? <lang futurebasic> end </lang>

Fōrmulæ

Fōrmulæ programs are not textual, visualization/edition of programs is done showing/manipulating structures but not text. Moreover, there can be multiple visual representations of the same program. Even though it is possible to have textual representation —i.e. XML, JSON— they are intended for storage and transfer purposes more than visualization and edition.

Programs in Fōrmulæ are created/edited online in its website, However they run on execution servers. By default remote servers are used, but they are limited in memory and processing power, since they are intended for demonstration and casual use. A local server can be downloaded and installed, it has no limitations (it runs in your own computer). Because of that, example programs can be fully visualized and edited, but some of them will not run if they require a moderate or heavy computation/memory resources, and no local server is being used.

In this page you can see the program(s) related to this task and their results.

Gambas

<lang gambas> Public Sub Main() End </lang>

Gecho

Empty programs are valid. <lang gecho></lang>

Gema

An empty program will copy input stream to output stream unchanged. <lang gema></lang>

Genyris

Global Script

This program is intended for use with the HS Global Script and uses its syntax for imperative programs. <lang Global Script>λ _. impunit 〈〉</lang>

Go

<lang go>package main func main() { }</lang>

Groovy

Haskell

Standard: Haskell 98

The simplest possible program is a single module using the implicit module header "module Main(main) where", and defining the action main to do nothing: <lang haskell>main = return ()</lang> The simplest possible module other than Main is one which contains no definitions: <lang haskell>module X where {}</lang>

Haxe

<lang haxe>class Program {

   static function main() {
   }

}</lang> Unlike most languages Haxe doesn't have arguments in the main function because it targets different platforms (some which don't support program arguments, eg: Flash or Javascript). You need to use the specific libraries of the platform you are targeting to get those.

HicEst

<lang hicest>END ! looks better, but is not really needed</lang>

HolyC

An empty file is the simplest valid HolyC program and returns 0.

HQ9+

An empty file is a valid HQ9+ program that does nothing.

HTML

HTML 5, section 12.1.2.4 Optional tags, allows to omit html, head and body tags. The implicit body element can be empty, but the implicit head element must contain a title element, says section 4.2.1 The head element. There seems no rule against an empty title. Therefore, the shortest correct HTML document is: <lang html5><!DOCTYPE html><title></title></lang>

The shortest correct XHTML document is: <lang html5><html xmlns="http://www.w3.org/1999/xhtml"><head><title /></head><body /></html></lang>

Huginn

i

<lang i>software{}</lang>

Icon and Unicon

<lang Icon>procedure main() # a null file will compile but generate a run-time error for missing main end</lang>

IDL

Inform 7

<lang inform7>X is a room</lang> Inform 7 is a language built for making interactive fiction, so a room needs to be defined for the player to start in.

Intercal

<lang intercal>PLEASE GIVE UP</lang>

Io

J

<lang j></lang> It returns itself: <lang j> -: ". 1</lang>

Java

Works with: Java version 1.5+

<lang java>public class EmptyApplet extends java.applet.Applet {

   @Override public void init() {
   }

}</lang>

<lang java>public class EmptyMainClass {

   public static void main(String... args) {
   }

}</lang>

The "..." basically means "as many of these as the programmer wants." Java will put multiple arguments into an array with the given name. This will work for any method where an array is an argument, but with a twist. A call can be made like this:

<lang java>method(arg0, arg1, arg2, arg3)</lang>

All of the args will be put into an array in the order they were in the call.

Works with: Java version 1.0+

<lang java>public class EmptyMainClass {

   public static void main(String[] args) {
   }

}</lang>

<lang java>public class EmptyApplet extends java.applet.Applet {

   public void init() {
   }

}</lang>

@Override - Indicates that a method declaration is intended to override a method declaration in a superclass. If a method is annotated with this annotation type but does not override a superclass method, compilers are required to generate an error message. It's present from JDK 5.0 (1.5.0) and up.

Actually this is not strictly correct. The smallest possible correct program in Java is an empty source file.

JavaScript

The empty file is a valid program.

Joy

Jq

The “empty” filter ignores its input and outputs nothing.

<lang jq>empty</lang>

Julia

Julia accepts an empty file as a program. <lang Julia></lang>

Output:

$ wc empty_program.jl
0 0 0 empty_program.jl
$ julia empty_program.jl
$

K

KonsolScript

<lang KonsolScript>function main() {

}</lang>

Kotlin

<lang scala>fun main(a: Array<String>) {}</lang>

Lambdatalk

An empty string is a valid program. <lang scheme></lang>

Lang5

Lasso

Lasso will parse any file thrown at it. It will ignore everything except what's inside specific Lasso delimiters. Thus a valid program that did nothing, could be an empty file. Perhaps more correct would be a file that had the specific delimiters and then nothing inside them. <lang Lasso>[]</lang> <lang Lasso><?lasso ?></lang> <lang Lasso><?= ?></lang>

$L a T e X$

<lang latex>\documentclass{minimal} \begin{document} \end{document}</lang>

LC3 Assembly

The only thing you absolutely need is a directive telling the assembler to stop assembling code (which in this case it has not actually started doing). <lang lc3asm> .END</lang>

Liberty BASIC

Lilypond

According to the manual, all lilypond programs should contain a version statement expressing the minimum version number. If this is missing then a warning will be emitted. <lang lilypond>\version "2.6.12"</lang>

An input file should really have a basic structure as follows. The compiler automatically adds some of the structure components if they are not present in the source code. However, explicit definition should be used to prevent the compiler from creating unwanted contexts (which can cause side effects):

<lang lilypond>\version "2.16.2"

\header {

}

\book {

 \score {
   \new Staff {
     \new Voice {

     }
   }
   \layout {

   }
 }

}</lang>

Lingo

"Program" doesn't really apply to Lingo. A Director projector (exe/app) doesn't have to contain any scripts/code. For scripts, the shortest possible code is: <lang lingo></lang>

Lisp

Most Lisp dialects, including Common Lisp, will accept no text (no forms) as a valid program. <lang lisp></lang>

Little Man Computer

V1.3 of Peter Higginson's implementation of Little Man Computer accepts an empty program. If it is assembled then ran in it, a single fetch cycle is performed, which adds 1 to the program counter, which was previously 0, then the address register then the instruction register, both of which were previously blank, are changed to 0. Similar behavior is seen in 101 Computing's implementation of Little Man Computer, in which all CPU registers start at 00, then the program counter changes to 1, the MAR to 0 and the MDR and CIR to 000.

Assembly <lang Little Man Computer></lang>

Machine code <lang Little Man Computer></lang>

Logo

<lang logo></lang> or end a standalone script with "bye" <lang logo>#! /usr/local/bin/logo

bye</lang>

LSE

LSE64

As with Forth, an empty file is the shortest program. To exit the interpreter at the end of a loaded file:

bye

Lua

M2000 Interpreter

Open M2000 Environment, type Edit A and place one space or insert a new line, then exit pressing Esc and write Save Empty (press enter). Now write New (press enter). Now write Load Empty (press enter) and execute it: write A (press enter). Now you can close environment: write End (press enter).

To open file Empty.gsb, as text file (without loading to list of modules) use Edit "Empty.Gsb". To open it in notepad, we can use this command from M2000 console: win "notepad", dir$+"empty.gsb"

We can open explorer for dir$ (the m2000 user directory) using Win Dir$ (we can use paths without quotes if no space includes, so win c:\ open explorer to c:)

File saved as: <lang M2000 Interpreter> MODULE GLOBAL A { } </lang> Because we make it in "level 0" (from console) this is a global module. A global module which loaded from console, or was a module loaded from a file at command line, when opening the environment, erased with an End, or a New, or a Start statement (reset of environment by software), or a Break by keyboard (although a dialog ask for proceed the breaking, the reset of environment) , or in some situation by using End Process from Task Manager.

If we wish to run it from command line (by clicking the file in explorer, and let m2000.exe open gsb files), we have to consider the first that this file not contain an execute statement, and that if we didn't use an input statement/function which need console, then console stay hide. To be sure that console open we have to use Show statement. To run A we have to include A at the last line (or append a line and write A). So we write in first line Show (press Esc to return to prompt) and save the file as Save Empty, A so we get this:

<lang M2000 Interpreter> MODULE GLOBAL A {Show } A </lang> We can open it with Edit "empty.gsb" add some statements between A and block of module, to make some globals, say a DIM a(10) which stay there until the end of current interpreter run (interpreter may run multiple times simultaneously). All globals are globals for current interpreter only.

We can run empty.gsb now (supposed we save it as Save Empty, A), from explorer or using a command in M2000 console which opens another interpreter (and can feed it with some numbers or and strings, but this is another story):

Use empty

So now we see environment again, with open console and at prompt (execution done, and stay open because no End statement executed after the A, or inside module as Set End). Set used to send commands to prompt by code.

Finally this is the code in a file (say Empty.gsb) to open, display something, waiting for a key (now a Show automatic happen) and then finish. We have to write it, in M2000 editor, and save it using Save Empty, A or in any editor and save it as empty.gsb in your desired folder. sav <lang M2000 Interpreter> MODULE GLOBAL A { Print "Hello World" a$=Key$ Set End } A </lang>

We can save it scrabbled text using Save "empty" @, A (not readable, but environment can revert the process using a unique key)

(m2000 is open source so key is not a mystery, but you can make your own clone, and use own key)

M4

Maple

Mathematica / Wolfram Language

MATLAB

<lang Matlab> function [varargout] = emptyprogram(varargin) </lang>

Maxima

<lang maxima>block()$</lang>

MAXScript

An empty MAXScript file returns "OK" on execution

MelonBasic

Metafont

Microsoft Small Basic

Output:

min

Works with: min version 0.19.3

MiniScript

MIPS Assembly

This just exits the program with exit code 0 (exit_success) <lang mips> .text main: li $v0, 10 syscall </lang>

МК-61/52

ML/I

MMIX

Modula-2

<lang modula2>MODULE Main;

BEGIN END Main.</lang>

Modula-3

<lang modula3>MODULE Main;

BEGIN END Main.</lang>

MUMPS

The empty file is a valid program.

N/t/roff

Works with: All implementations of TROFF

An empty input file is valid, but if the output is Postscript or PDF, most PDF viewers will suffer. However, that's the PDF viewer's fault; the typesetter is still okay with an empty file. If one wants grace for the PDF viewers, import a macro that, at the very least, defines some proper margins and pagination as in the following code:

Works with: GNU TROFF version 1.22.2

Nanoquery

Empty files are valid Nanoquery programs that do nothing. <lang Nanoquery></lang>

Nemerle

Compiles with warnings: <lang Nemerle>null</lang> Compiles without warnings (so, more correct): <lang Nemerle>module Program {

   Main() : void
   {
   }

}</lang>

NetRexx

The following two samples both generate valid programs.

This minimal example requires that the file be named to match the class: <lang NetRexx>class empty</lang>

This example will generate its class based on the file name: <lang NetRexx>method main(args = String[]) static</lang>

NewLISP

Nim

Nit

Although a Nit module (file) usually include a module declaration, an empty module is a valid Nit program.

NS-HUBASIC

Objeck

<lang objeck>bundle Default {

 class Empty {
   function : Main(args : String[]) ~ Nil {
   }

}</lang>

Objective-C

Works with: gcc version 4.0.1

<lang objc>int main(int argc, const char **argv) {

   return 0;

}</lang>

The minimal empty Cocoa/OpenStep application, useful as life-support for many examples given at RosettaCode, is <lang objc>#import <Cocoa/Cocoa.h>

int main( int argc, const char *argv[] ) {

 @autoreleasepool {
   [NSApplication sharedApplication];
 }
 return 0;

}</lang>

OCaml

Works with: Ocaml version 3.09

Actually, the smallest possible correct program in OCaml is an empty source file.

Octave

An empty text file can be a valid empty program, but since Octave has the concept of "function file" (a file containing a single function; the file is automatically loaded when a function with the same name of the file, save for the extension, is called, and the first function present in the file is used), the name of the empty file matters. E.g. calling an empty file as isempty.m makes unusable the builtin isempty function.

Oforth

An empty file is a valid oforth file

<lang Oforth>oforth empty.of</lang>

Without file, interpreter can just evaluate bye : <lang Oforth>oforth --P"bye"</lang>

Ol

An empty file is considered the smallest runnable code.

A single comment can be considered a valid program that does nothing.

A file with any one-digit number ("0", "1", .. "9") or one-character function like "+", "-", etc.) is smallest non empty runnable code.

OOC

The Compiler will accept an empty file: <lang ooc></lang>

OpenLisp

We can run OpenLisp in shell mode with an empty program as follows. This is for the Linux version of OpenLisp.

!/openlisp/uxlisp -shell

() </lang>

OxygenBasic

The smallest possible program is a single space character: <lang oxygenbasic>

</lang>

Oz

Accepted by compiler

The simplest 'program' that can be compiled is a file which contains a single expression. <lang oz>unit</lang> Such a 'program' cannot be executed, though.

Standalone

The simplest standalone program is a root functor that does not define anything. ("Functors" are first-class modules.) <lang oz>functor define

  skip

end</lang>

PARI/GP

Pascal

<lang pascal>program ProgramName;

begin end.</lang> The first line is not necessary in modern Pascal dialects. With today's most compilers, the empty program is just: <lang pascal>begin end.</lang>

PepsiScript

For typing: <lang PepsiScript>#include default-libraries

author .

class .:</lang> For importing:

While • is valid, the example below is the smallest possible "compiled" program that can be made normally.

•dl◘.◙

Perl

The empty program is valid and does nothing but return a successful exit code:

Of course, this then requires you to specify the interpreter on the command line (i.e. perl empty.pl). So slightly more correct as a stand-alone program, is:

The smallest possible Perl one-liner is perl -e0.

Phix

Library: Phix/basics

An empty file is a valid program. When compiled however, it is far from empty as it contains most of the VM and a full run-time diagnostics kit (together about 202K).

PHP

An empty text file is a correct PHP program that does nothing.

PicoLisp

Pike

PIR

The :main pragma indicates that a subroutine is the program's entry point. However, if a subroutine is the first (or only, which would also have the effect of making it the first) routine in the program, Parrot will use that. So we may comfortably omit it in this case. <lang pir>.sub empty_program .end</lang>

Pixilang

Any text longer than 0 characters is valid, otherwise resulting in a "The file is empty or does not exist" error. In this example, a space character is used. <lang Pixilang> </lang>

PL/I

<lang PL/I>s: proc options (main); end;</lang>

PL/SQL

<lang sql>BEGIN

   NULL;

END;</lang>

Plain English

<lang plainenglish>To run: Start up. Shut down.</lang>

Plain $T e X$

Pony

<lang pony>actor Main new create(e: Env) => ""</lang>

Pop11

Pop11 has two compilers, incremental and batch compiler. For the incremental compiler one can use just empty program text (empty file), or a file containing nothing but a comment, e.g. <lang pop11>;;; This is a valid Pop11 program that does absolutely nothing.</lang> The batch compiler generates an executable which starts at a given entry point, so one should provide an empty function. If one wants program that works the same both with incremental compiler and batch compiler the following may be useful: <lang pop11>compile_mode :pop11 +strict; define entry_point(); enddefine;

_TERMIN_IF DEF POPC_COMPILING

entry_point();</lang> Here the batch compiler will stop reading source before call to entry_point while incremental compiler will execute the call, ensuring that in both cases execution will start from the function entry_point.

PostScript

An empty file is a valid PostScript program that does nothing.

Following good programming practice, however, and to ensure that a PostScript printer will interpret a file correctly, one should make the first 4 characters of the file be <lang postscript>%!PS</lang>

If a particular version of the PS interpreter is needed, this would be included right there: <lang postscript>%!PS-2.0 % ...or... %!PS-3.0 % etc</lang>

PowerShell

An empty script block. A script block is a nameless (lamda) function. <lang PowerShell> &{} </lang>

Output:

Processing

An empty .pde sketch file. <lang Processing></lang> When run this will produce a 200x200 inactive default gray canvas.

ProDOS

This is an acceptable program: <lang ProDOS>IGNORELINE</lang> But also you could include a delimiter character recognized by the compiler/interpreter: <lang ProDOS>;</lang>

Programming Language

For typing: <lang Programming Language></lang> For importing:

At best, the code can have one line, which is empty. The smallest way to achieve this is to type nothing. However, this is the smallest possible "compiled" program that can be generated via the compiler:

[

PSQL

<lang sql>EXECUTE BLOCK AS BEGIN END</lang>

PureBasic

An empty file is a correct PureBasic program that does nothing. <lang PureBasic></lang>

Python

An empty text file is a correct Python program that does nothing.

An empty file named __init__.py even has a structural purpose in Python of declaring that a directory is a Package.

QUACKASM

Quackery

An empty string or text file is a valid Quackery program that does nothing.

Output:

Quite BASIC

R

An empty text file is a valid empty program

Racket

The following shows an empty program in Racket's default language. Other Racket languages may impose different conditions on the empty program. <lang racket>

lang racket

</lang>

Raku

(formerly Perl 6)

The empty program is valid and does nothing but return a successful exit code: <lang perl6></lang>

It is also possible to just specify that the program is written in Raku: <lang perl6>use v6;</lang>

or even: <lang perl6>v6;</lang>

Raven

An empty text file is an empty program.

REBOL

The header section is mandatory if you want it to be recognized as a REBOL program. It doesn't have to be filled in though: <lang REBOL>REBOL []</lang>

Retro

An empty file is the smallest valid program.

REXX

An empty (or blank) file is a valid REXX program.

Some REXX implementations require a special comment [1^st word in the comment must be REXX (in upper/lower/mixed) case]
to distinguish from other types of scripting languages, and the comment must be the 1^st line as well as the REXX word.

But a null program (or a program with only blanks in it) in those other scripting languages is also considered a valid program.

version 1

This program can be empty (no characters), or a program with (only) one or more blanks. <lang rexx></lang>

version 2

REXX on MVS/TSO requires REXX to be within a REXX comment that begins on the first line: <lang rexx>/*REXX*/</lang>

Rhope

Works with: Rhope version alpha 1

Main(0,0)
|: :|

Ring

Robotic

Ruby

An empty file is a valid Ruby program. However, in order to make it runnable on *nix systems, a shebang line is necessary: <lang ruby>#!/usr/bin/env ruby</lang>

Run BASIC

<lang runbasic>end ' actually a blank is ok</lang>

Rust

Scala

<lang scala>object emptyProgram extends App {}</lang>

Scheme

Scilab

ScratchScript

An empty program is invalid because it gives an [Err: Undefined] error. This behaviour still applies when the program isn't running. Due to this error, a program containing only an empty comment is the smallest possible valid program. <lang ScratchScript>//</lang>

Seed7

<lang seed7>$ include "seed7_05.s7i";

const proc: main is noop;</lang>

Set lang

Sidef

SimpleCode

Simula

Works with: SIMULA-67

<lang simula>BEGIN END</lang>

Slate

Smalltalk

SNOBOL4

A valid program requires an end label. The shortest (virtually empty) program is then: <lang snobol>end</lang>

SNUSP

$#

$ sets the instruction pointer (going right), and # halts the program (empty stack).

Sparkling

SQL PL

Works with: Db2 LUW

With SQL only: <lang sql pl> SELECT 1 FROM sysibm.sysdummy1; </lang> Output:

db2 -t
db2 => SELECT 1 FROM sysibm.sysdummy1;

1        
------------
           1

  1 record(s) selected.

Works with: Db2 LUW

With SQL PL: <lang sql pl> --#SET TERMINATOR @

CREATE PROCEDURE myProc ()

BEGIN
END @

</lang> Output:

db2 -td@
db2 => CREATE PROCEDURE myProc ()
...
db2 (cont.) =>  END @
DB20000I  The SQL command completed successfully.

Works with: Db2 LUW

version 9.7 or higher.

With SQL PL: <lang sql pl> BEGIN END; </lang> Output:

db2 -t
db2 => BEGIN
db2 (cont.) => END;
DB20000I  The SQL command completed successfully.

SSEM

A completely empty program—all store bits clear, just power the machine up and hit Run—is meaningful in SSEM code and even does something, although not something desirable: <lang ssem>00000000000000000000000000000000 0. 0 to CI jump to store(0) + 1 00000000000000000000000000000000 1. 0 to CI jump to store(0) + 1</lang> Since the number in address 0 is 0, this is equivalent to

    goto 1;
1:  goto 1;

and has the effect of putting the machine into an infinite loop.

The smallest program that will terminate is: <lang ssem>00000000000001110000000000000000 0. Stop</lang>

Standard ML

Actually, the smallest possible correct program in Standard ML is an empty source file.

Stata

Stata does not accept an empty program, so we have to do something. Here we only declare the minimum version of the interpreter for the program.

<lang stata>program define nop

       version 15

end</lang>

It's also possible to define an empty function in Mata.

<lang stata>function nop() {}</lang>

Suneido

<lang Suneido>function () { }</lang>

Swift

Symsyn

Tcl

Nothing is mandatory in Tcl, so an empty file named nothing.tcl would be a valid "empty program". <lang tcl></lang>

TI-83 BASIC

<lang TI-BASIC></lang> Displays "Done". If an empty program isn't valid, there are numerous other one-byte solutions:

Disp

Return

Stop

TI-83 Hex Assembly

<lang TI-BASIC>PROGRAM:EMPTY

AsmPrgmC9</lang>

TI-89 BASIC

Prgm
EndPrgm

Tiny BASIC

An empty program works just fine. <lang Tiny BASIC></lang>

Toka

For interpreted code, nothing is required, although bye is necessary for an empty script to exit (rather than wait for the user to exit the listener). Hence:

bye

Or, for a directly runnable script:

#! /usr/bin/toka
bye

For compiled code, the simplest program is an empty quote:

[ ]

Again, to exit the listener, you will still need user input if this is not followed with bye.

Trith

TUSCRIPT

<lang tuscript>$$ MODE TUSCRIPT</lang>

UNIX Shell

Works with: Bourne Shell

Works with: Bourne Again SHell

Works with: Korn SHell

Unlambda

(See how i plays so many roles in unlambda?)

Ursa

The Cygnus/X Ursa interpreter has no problems with empty files, so the shortest program is an empty file. <lang ursa></lang>

Vala

VAX Assembly

<lang VAX Assembly>0000 0000 1 .entry main,0 ;register save mask

 04  0002     2 	ret	;return from main procedure
     0003     3 .end	main	;start address for linker</lang>

VBA

Same as Visual Basic, VB6, etc. <lang vb>Sub Demo() End Sub</lang>

VBScript

An empty .vbs file is considered the smallest runnable code, but the following (a single apostrophe as comment marker) would also be acceptable (along with other non-executing instructions like option explicit.) <lang vb>'</lang>

Verbexx

An empty file is the smallest valid script, but running it does nothing. <lang verbexx></lang>

VHDL

Compiled and simulated by Modelsim: <lang VHDL>entity dummy is end;

architecture empty of dummy is begin end;</lang>

Vim Script

An empty file is a valid program.

Visual Basic

Works with: VB6 <lang vb>Sub Main() End Sub</lang>

Visual Basic .NET

Works with: Visual Basic .NET version 2005

<lang vbnet>Module General

   Sub Main()
   End Sub

End Module</lang>

Vlang

V can compile a 0 length, or whitespace only file as "empty", and "correct".

Output:

prompt$ ls -s blank.v
0 blank.v
prompt$ v run blank.v
prompt$ echo $?
0

A more reasonable example, that someone might guess was a V program, and not just an emptiness: <lang go>{}</lang>

For an even better chance at guessing that the file is meant as V source code:

<lang go>module main pub fn main() {}</lang>

Wart

WDTE

An empty 'file' is a valid WDTE script. That being said, WDTE has no inherent concept of scripts being in files, so a zero-length input may be a better description.

WebAssembly

Library: WASI

<lang webassembly>(module

   ;;The entry point for WASI is called _start
   (func $main (export "_start")
   
   )

) </lang>

Wee Basic

Wren

X86 Assembly

Works with: NASM version Linux

<lang asm>section .text global _start

_start: mov eax, 1 int 0x80 ret</lang>

Works with: MASM

<lang asm>.386 .model flat, stdcall option casemap:none

.code start: ret end start</lang>

XPL0

An empty file compiles and builds an EXE file with a single RET instruction, but of course does nothing when executed.

XQuery

<lang xquery>.</lang> The dot selects the current context node and returns it unchanged.

XSLT

Add other namespaces to the stylesheet attributes (like xmlns:fo="http://www.w3.org/1999/XSL/Format") if you use them.

Since XSLT is XML, and transform is a synonym for stylesheet, the example above can be minified to: <lang xslt><transform xmlns="http://www.w3.org/1999/XSL/Transform" version="1.0"/></lang>

This stylesheet echoes the text content of an XML file. The shortest stylesheet without any output would be <lang xslt><transform xmlns="http://www.w3.org/1999/XSL/Transform" version="1.0">

  <template match="/" />

</transform></lang>

xTalk

Works with: HyperCard

Works with: LiveCode

on startup
  
end startup

XUL

Yorick

An empty file is valid and does nothing.

Z80 Assembly

Amstrad CPC, ZX Spectrum, etc.

Most 8-bit computers work in a similar fashion: The BASIC interpreter acts as an operating system, and your entire program is essentially a subroutine that BASIC will CALL. If you "return" from your program the computer will go back to BASIC.

Game Boy

Translation of: Game Boy Advance

The Nintendo logo is loaded from the cartridge header, and the Game Boy's firmware won't boot the game without it. In addition, the firmware also reads a checksum of the cartridge contents and won't boot the game if it doesn't match the checksum stored in the header. So a truly "empty" program can't be run at all. Thus a minimum of a valid cartridge header is required for an empty program that the Game Boy can actually run. The beginning of the cartridge header is a jump to the program's start.

<lang z80>ProgramStart: nop ;not sure if this is needed but Game Boy is somewhat buggy at times and the tutorials I used all did it di ;disable interrupts foo: jp foo ;trap the program counter here. (Don't do this on a real Game Boy, you'll drain the batteries much faster than usual.)</lang>

¶0¶

ZX Spectrum Basic

See BASIC