Const and compile-time evaluation

An important point before introducing more advanced features is the const keyword, that will be used to define compile-time values.

const ALWAYS_IN_SCREAMING_SNAKE_CASE = 10;
let a = ALWAYS_IN_SCREAMING_SNAKE_CASE;     // a = 10
let b <- ALWAYS_IN_SCREAMING_SNAKE_CASE;    // compile error! can't move a const value
const ALWAYS_IN_SCREAMING_SNAKE_CASE = 2;   // compile error! can't re-define a const value

The const keyword will be used to define compile-time values, that can be used in the code, for example:

const PI = 3.1416;

const fn area_of_circle(radius: f32): f32 {
    return PI * radius * radius;
}

let my_circle = area_of_circle(10); // 314.16, calculated at compile-time

With the const keyword you can't:

const a class or struct
const a function that have side-effects
const a function that have a return value that can't be evaluated at compile-time
const a value that can't be evaluated at compile-time
const a function that move values

Orbis

Const and compile-time evaluation