PROC main()
    WriteF('Hello, World!')
ENDPROC

And repeating one:

PROC main()
    WHILE TRUE DO WriteF('Hello, World!')
ENDPROC

#include <iostream.h>

main()
{
    for(;;)
    {
        cout << "Hello World! ";
    }}

Function H ()
    up
    left 90
    Down
    Forward 10
    Backward 5
    right 90
    Forward 5
    right 90
    Backward 5
    Forward 10
    left 90
    Up
    forward 5
    
Function E()
    Down
    forward 5
    Backward 5
    left 90
    Forward 5
    right 90
    Forward 3
    Backward 3
    left 90
    Forward 5
    right 90
    Forward 5
    Up
    right 90
    Forward 10
    left 90
    forward 5
    
Function L()
    Forward 5
    Down
    Backward 5
    Left 90
    Forward 10
    Up
    Right 90
    Forward 10
    Right 90
    Forward 10
    Left 90
    Up

Function O()
    Down
    Repeat 2
        Forward 5
        Left 90
        Forward 10
        Left 90
    up
    forward 10
    
function D()
    Down
    Forward 3
    Left 45
    forward 1.5
    left 45
    Forward 8
    left 45
    forward 1.5
    left 45
    forward 3
    left 90
    forward 10
    up
    left 90
    forward 10
    
function W()
    left 90
    forward 10
    down
    backward 10
    right 45
    forward 5
    right 90
    forward 5
    left 135
    forward 10
    up
    right 90
    forward 5
    right 90
    forward 10
    left 90
    

Function R()
    down
    left 90
    forward 10
    right 90
    forward 3
    right 45
    forward 1.5
    right 45
    forward 2
    right 45
    forward 1.5
    right 45
    forward 3
    left 135
    forward 8.5
    up
    left 45
    forward 5

straight
y=0
repeat 10  
    up
    y=y-15
    goto 0,y,0
    forward 10
    right 90
    forward 10
    left 90
    H()
    E()
    L()
    L()
    O()
    Forward 5
    W()
    O()
    R()
    L()
    D()

  print "Hello, World!\n" while (1);

%!PS
1.00000 0.99083 scale
/Courier findfont 12 scalefont setfont
0 0 translate
/row 769 def
85 {/col 18 def 6 {col row moveto (Hello World)show /col col 90 add def}
repeat /row row 9 sub def} repeat
showpage save restore

while {1} {
      puts "Hello World "
     }

VERSION 2.00
Begin Form Form1 
   Caption         =   "Hello World!"
   ClientHeight    =   540
   ClientLeft      =   1095
   ClientTop       =   1515
   ClientWidth     =   2445
   Height          =   945
   Left            =   1035
   LinkTopic       =   "Form1"
   ScaleHeight     =   540
   ScaleWidth      =   2445
   Top             =   1170
   Width           =   2565
   Begin Label Label1 
      Alignment       =   2  'Center
      Caption         =   "Hello World!"
      FontBold        =   -1  'True
      FontItalic      =   0   'False
      FontName        =   "Arial"
      FontSize        =   12
      FontStrikethru  =   0   'False
      FontUnderline   =   0   'False
      Height          =   255
      Left            =   120
      TabIndex        =   0
      Top             =   120
      Width           =   2175
   End
End

------------------------------------------------------------------------------------------------HELLOW.DPR
------------------------------------------------------------------------------------------------
program HelloW;

uses
  Forms,
  Main in 'MAIN.PAS' {fmHelloWorld};

{$R *.RES}

begin
  Application.CreateForm(TfmHelloWorld, fmHelloWorld);
  Application.Run;
end.

------------------------------------------------------------------------------------------------MAIN.PAS
------------------------------------------------------------------------------------------------
unit Main.pas;

interface

uses
  SysUtils, WinTypes, WinProcs, Messages, Classes, Graphics, Controls,
  Forms, Dialogs;

type
  TfmHelloWorld = class(TForm)
    txHelloWorld: TLabel;
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  fmHelloWorld: TfmHelloWorld;

implementation

{$R *.DFM}

end.

------------------------------------------------------------------------------------------------MAIN.DFM
------------------------------------------------------------------------------------------------
object fmHelloWorld: TfmHelloWorld
  Left = 200
  Top = 99
  Width = 435
  Height = 300
  Caption = 'fmHelloWorld'
  Font.Color = clWindowText
  Font.Height = -13
  Font.Name = 'System'
  Font.Style = []
  PixelsPerInch = 96
  TextHeight = 16
  object txHelloWorld: TLabel
    Left = 115
    Top = 70
    Width = 77
    Height = 16
    Caption = 'Hello World'
  end
end

------------------------------------------------------------------------------------------------

program macosHelloWorld;

var
    theWindow: WindowPtr;
    wBoundsRect: rect;
    gDone: boolean;
    myEvent: EventRecord;
    gotEvent: Boolean;                    {is returned event for me?}


procedure initToolbox;
    begin
        InitGraf(@thePort);               {initialize QuickDraw}
        InitFonts;                        {initialize Font Manager}
        InitWindows;                      {initialize Window Manager}
        TEInit;                           {initialize TextEdit}

        FlushEvents(everyEvent, 0);       {clear event queue}
        InitCursor;                       {initialize cursor to arrow}
    end; {initToolbox}


procedure drawTheText (w: WindowPtr);     {Draw the text on the window}
    const
        s = 'Hello, World!';
    var
        textLength, textHeight: integer;
        x, y: integer;
        info: fontInfo;
    begin
        setPort(w);                       {sets up the drawing port}
        TextFont(applFont);               {geneva}
        TextFace([]);                     {plain text}
        TextSize(72);                     {72 pts}

        GetFontInfo(info);                {get info on font height}

        textLength := StringWidth(s);     {save width and height}
        textHeight := info.ascent + info.leading;

                                          {center text on screen}

        x := (w^.portRect.right) - (w^.portRect.left);
        x := round(x / 2);

        x := round(x - (textLength / 2));

        y := (w^.portRect.bottom) - (w^.portRect.top);
        y := round(y / 2);

        y := round(y - (textHeight / 2));

        MoveTo(x, y);                     {draw the stuff}
        DrawString(s);

    end; {drawTheText}

begin {macosHelloWorld}
    initToolbox;
    gDone := false;

    with screenBits.bounds do             {set the window size based on
the screen size}
        setRect(wBoundsRect, left + 4, top + 40, right - 4, bottom - 4);
                                          {create a new window}
    theWindow := newWindow(nil, wBoundsRect, '', true, documentProc,
pointer(-1), false, 0);

    drawTheText(theWindow);

    repeat                                {wait until the user clicks
the mouse}
        gotEvent := WaitNextEvent(everyEvent, myEvent, 15, nil);
        if gotEvent then
            case myEvent.what of
                mouseDown: 
                    gDone := true;
                otherwise
                    ;
            end; {case}
    until gDone;

    DisposeWindow(theWindow);             {clear up window memory}

end. {macosHelloWorld}

;"hello, world" in assembly language for Linux
;
;to compile:
;
;nasm -f elf hello.asm
;ld -s -o hello hello.o

section	.text
    global _start			;must be declared for linker (ld)

msg	db	'Hello, world!',0xa	;our dear string
len	equ	$ - msg			;length of our dear string

_start:					;tell linker entry point

	mov	edx,len	;message length
	mov	ecx,msg	;message to write
	mov	ebx,1	;file descriptor (stdout)
	mov	eax,4	;system call number (sys_write)
	int	0x80	;call kernel

	mov	eax,1	;system call number (sys_exit)
	int	0x80	;call kernel

;"hello, world" in assembly language for FreeBSD (and possibly other *BSD)
;
;to compile:
;
;nasm -f elf hello.asm
;ld -s -o hello hello.o

section	.text
    global _start			;must be declared for linker (ld)

msg	db	"Hello, world!",0xa	;our dear string
len	equ	$ - msg			;length of our dear string

_syscall:		
	int	0x80		;system call
	ret

_start:				;tell linker entry point

	push	dword len	;message length
	push	dword msg	;message to write
	push	dword 1		;file descriptor (stdout)
	mov	eax,0x4		;system call number (sys_write)
	call	_syscall	;call kernel

				;the alternate way to call kernel:
				;push	eax
				;call	7:0

	add	esp,12		;clean stack (3 arguments * 4)

	push	dword 0		;exit code
	mov	eax,0x1		;system call number (sys_exit)
	call	_syscall	;call kernel

				;we do not return from sys_exit,
				;there's no need to clean stack

;"hello, world" in assembly language for BeOS
;
;to compile:
;
;nasm -f elf hello.asm
;ld -s -o hello hello.o

section	.text
    global _start			;must be declared for linker (ld)

msg	db	"Hello, world!",0xa	;our dear string
len	equ	$ - msg			;length of our dear string

_syscall:			;system call
	int	0x25
	ret

_start:				;tell linker entry point

	push	dword len	;message length
	push	dword msg	;message to write
	push	dword 1		;file descriptor (stdout)
	mov	eax,0x3		;system call number (sys_write)
	call	_syscall	;call kernel
	add	esp,12		;clean stack (3 * 4)

	push	dword 0		;exit code
	mov	eax,0x3f	;system call number (sys_exit)
	call	_syscall	;call kernel
				;no need to clean stack

#include <stdio.h>

int main (int argc, char **argv)
{
    printf ("Hello, world!");
    return 0;
}