2. hello world

Before getting into all the details of the alv language, let’s quickly run an example program to make sure that everything is working correctly:

([1]import* time)
([2]print ([3]every 0.5 "hello world!"))

Open a text file save this piece of code as hello.alv. You can also find this example program in the repository and the windows binary package.

As mentioned earlier, there are two different ways to run alv programs: using the copilot GUI, or in the terminal.

starting the copilot GUI

On Linux and Mac OS X, you can launch the GUI by executing the alv-fltk command. On Windows, you can double-click alv-fltk.bat. This window should open:

Now open hello.alv using File > Open Script or the shortcut ^O (control-O). The copilot should start printing hello world over and over again in the lower field.

You can pause and resume execution using the Run button or the ^P shortcut. To stop the program simply close the window.

starting the copilot in the terminal

To run a file in the terminal, invoke the command alv <path/to/hello.alv>. If your system cannot find the alv command, check your installation and PATH. On Windows, it is also possible to drag your alv file onto alv.bat.

You should now see the text hello world being printed over and over again, twice a second. You can stop the copilot by pressing ^C (control-C).