Hello world#

First you need the compiler. If you do not have it yet, go through installing Vesta and come back; it takes a few minutes.

The program#

Save this as hello.vx:

i32 main() {
    println("Hello from Vesta ${1 + 1}!");
    return 0;
}

Build it and run it#

Vesta compiles to a bytecode with the .velb extension, which its virtual machine runs:

vesta --vx hello.vx -o hello
vesta --run hello.velb

You should see:

Hello from Vesta 2!

If instead you get an error about modules that cannot be found, the compiler is not locating the standard library. The cause and the fix are in where the standard library lives.

What each line says#

i32 main() declares the entry point. The type comes before the name, as in C or Java, and it returns the process exit code: 0 means everything went fine.

println writes a line to standard output. You do not need to import anything to use it.

The interesting part is inside the string. ${1 + 1} is interpolation: whatever sits between the braces is evaluated and its result is placed into the text. And because 1 + 1 is an expression the compiler can work out on its own, no addition survives into the final program: the binary carries the string Hello from Vesta 2! directly.

It is a tiny example of something you will see everywhere in Vesta: what can be known at build time is not paid for at run time.

Next#

The program you just compiled can run in three different ways without you changing a single line. That is what comes next.