Getting Started

The first thing you need to learn about in Rune is the dbg function. This is used to "debug" values provided to it in order to understand them. Anything can be provided to it, and it will do its best to describe it.

fn function() {
    42
}

let a = [1, 2, 3];
let b = '今';
let closure = || println!("Hello");

dbg!(a);
dbg!(b);
dbg!(function);
dbg!(drop);
dbg!(closure);

Note: by convention Rune uses files ending in .rn.

$> cargo run -- run scripts/book/getting_started/dbg.rn
[1, 2, 3]
'今'
dynamic function (at: 0x1a)
native function (0x1bd03b8ee40)
dynamic function (at: 0x17)

The default dbg implementation outputs information on its arguments to stdout. But its exact behavior can differ depending on how the environment is configured. When Rune is embedded into a larger application it might for example be more suitable to output to a log file.

Rune also provides print! and println! macros which can be used to format directly to stdout, but these cannot be relied on to be present to the same degree as dbg. However for our purposes we will be using rune-cli, which has all of these modules installed. This is also what was used to run the above code.

So for a more formal introduction, here is the official Rune "Hello World":

println!("Hello World");

$> cargo run -- run scripts/book/getting_started/hello_world.rn
Hello World

So now you know how to run Rune scripts. Well done! Let's move on to the next chapter.