Your first program

This chapter prints one line and then turns the program into an executable you can run directly.

Prepare Xen

You need Xen on Linux. Follow the installation guide. Add the distribution’s bin directory to PATH to use xen from any directory. Commands in this guide assume xen is available on your path.

From an extracted distribution, you can replace xen with ./bin/xen. From the repository root, use compiler/dist/xen. Keep bin and stdlib together when moving a distribution.

xen version

Write a file

Create hello.xen in a working directory and save this code:

fn main() {
    println("Hello, Xen!");
}

fn main() is where execution begins. Statements go inside braces. println prints a value followed by a newline. Put strings in double quotes and end statements with ;.

Run this command from the directory containing your file:

$ xen run hello.xen
Hello, Xen!

Check and build

xen check hello.xen
xen build hello.xen -o hello
./hello

check finds errors without running the program. Success produces no output. build creates an executable. ./hello also prints Hello, Xen!; running that file does not require Xen.

If Xen cannot find your file, check the working directory and filename. Executables need a compatible Linux system. macOS and Windows are unsupported.

Try a change

Replace the greeting with your own name and run it again. The next chapter gives names to values and uses them in calculations.