XPL0

<h2 id="examples">Examples</h2>
This is how the traditional Hello World program is coded in XPL0:

 code Text=12;
 Text(0, "Hello World!")

Text is a built-in routine that outputs a string of characters. The zero (0) tells where to send the string. In this case it is sent to the display screen, but it could just as easily be sent to a printer, a file, or out a serial port by using a different number.
In XPL0 all names must be declared before they can be used. The command word code associates the name Text to built-in routine number 12, which is the one that outputs strings. There are about a hundred of these built-in routines that provide capabilities such as input and output, graphics, and trig functions.
The 32-bit versions of the compilers automatically insert code declarations, thus the program above can simply be written as:

 Text(0, "Hello World!")

The <a href="/facts/TPK_algorithm/0cq9M6CK">TPK algorithm</a> provides an example that can be compared to other languages:

 func real F(T);
 real T;
 return sqrt(abs(T)) + 5.*Pow(T, 3.);
 
 int I; real Y, A(11);
 [for I:= 0 to 10 do A(I):= RlIn(0);
 for I:= 10 downto 0 do
 [Y:= F(A(I));
 if Y > 400. then [IntOut(0, I); Text(0, " TOO LARGE")]
 else [IntOut(0, I); RlOut(0, Y)];
 CrLf(0);
 ];
 ]

Graphics has been a feature of XPL0 since its days on the Apple II computer.

int X, Y, Color;
       [SetVid($101); \set video mode to 640x480x8
       repeat  for Y:= 0 to 128-1 do
                   for X:= 0 to 128-1 do
                       Point(X, Y,  X or Y xor Color);
               Color:= Color+1;
               DelayUS(50_000); \0.05 seconds
       until   ChkKey;
       ]

<ul><li>Fish, Larry (February 1979). "A Block-Structured Language for Microcomputers". Kilobaud, p. 24.</li></ul>
<h2 id="external-links">External links</h2>
<ul><li><a href="http://www.xpl0.org">XPL0 official website</a></li>
<li><a href="http://www.xpl0.org/manual.pdf">XPL0 Programming Language Manual</a></li>
<li><a href="http://www.6502group.org/hist6502.html">The story behind Apex and XPL0</a></li></ul>

XPL0 open-in-new

XPL0