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HelloWorld Program in WANTScript
   

By Andrew J. Wozniewicz
Milwaukee, August 6, 2008

"HelloWorld" is the traditional first program in just about any programming language, so we will continue the tradition here.

The idea of a HelloWorld program is to write a single line of text to the output device (console), as follows:

Hello world!

To output (or "write") a line of text to the console in WANTScript, you can use the built-in System.IO.Console.WriteLn function. A possible HelloWord program looks like this in WANTScript:

System.IO.Console.WriteLn("Hello world!")

That's all there is to it - a HelloWorld WANTScript project is a single line of code. You can save this one line into a text file hello.want and execute it. WANT automatically creates a project named DEFAULT if you don't explicitly specify a project name. The above single line of code is thus exactly equivalent to the following:

project DEFAULT
  System.IO.Console.WriteLn("Hello world!")
end

Now, if you want to output more than a single line of text, or if you are a Pascal programmer (or both), you would probably object to writing the fully-qualified name System.IO.Console.WriteLn every time you want to output a line. Good news is that, instead of always using fully qualified names, you could just import the entire System.IO.Console module, which - besides WriteLn - contains some other useful functions and then use these functions directly, without qualification. This is analogous to the uses-clause in Pascal. You can import another module like this:

project HelloWorld
  import System.IO.Console
  WriteLn("Hello world!")
end

When you use the import directive, it makes all the publicly visible symbols from the imported module available in the importing module. That way, you can use the WriteLn function pretty much the same way you would use it in Pascal, without any qualification, like the above example illustrates.

Now, even better news is that you don't need to bother importing System.IO.Console explicitly at all, since it is automatically and implicitly imported for you by the WANT Runtime. So, you could have written the HelloWorld project simply as follows:

project HelloWorld
  WriteLn("Hello world!")
end

That's not all, though. Since you already know that you can omit the project header - if you are happy with the default project name of DEFAULT - the entire HelloWorld program in WANTScript boils down to this single line of code:

WriteLn("Hello world!")

Not bad, but it gets even better! In WANTScript, you can use a literal value, like the "Hello world!" above, which is a string literal, in place of a statement. It is automatically understood by the interpreter to mean a call to the WriteLn procedure, with the literal as its argument. So, the above line is exactly equivalent to

"Hello world!"

Now, even this can be simplified. WANTScript does not require that you terminate your string literals. It will automatically terminate them for you at the end-of-line. So, you can rewrite the above to

"Hello world!

Finally, since you can use either single or double quotes, you could equally well have written

'Hello world!

which arguably holds the world's record for the shortest HelloWorld program ever.

So now we've come full circle. The HelloWorld program in WANTScript could be a very simple single line of code, if you wanted, but having seen these many different variations on that theme should have given you a better feel for some of WANTScript syntax.

-Andrew