Balaur Script

Balaur Script is the language of game scripts and of the editor itself. A .bs file is statically typed, reads like Rust, and compiles to WebAssembly when it is saved. A running game picks up the new code and keeps its state.

enum Shape { Circle(float), Rect { w: float, h: float }, Empty }

fn area(s: Shape) -> float {
    match s {
        Shape::Circle(r) => r * r * 3.0,
        Shape::Rect { w, h } => w * h,
        Shape::Empty => 0.0,
    }
}

pub fn total() -> float {
    let shapes = [Shape::Circle(2.0), Shape::Rect { w: 2.0, h: 3.5 }, Shape::Empty];
    let sum = 0.0;
    for s in shapes {
        sum += area(s);
    }
    sum
}

// total() == 19.0

How this chapter is laid out

Each page teaches one concept and builds on the pages before it. The pages read in order, and each stands alone when you come back to look something up.

The script modules reference lists every engine function. The Scripting manual page covers the editor, the debugger and hot reload.

How to read the examples

A comment under an example says what a call answers:

pub fn double(x: int) -> int { x * 2 }

// double(21) == 42

Some calls end in a trap, which stops the call at run time. Others do not compile, and the comment gives the compiler's own message with its line and column:

pub fn half(n: int) -> int { n / 0 }
pub fn broken() -> int { 1 + true }

// error: 2:28: cannot combine int and bool

Trying the examples shows how to run any of them on your own machine.