Const Func

A const func is a function the compiler can evaluate at compile time: the compiler executes the function body during compilation and materializes the result as a constant. It has two faces — ordinary function and constant capability: at runtime it is called as usual, and in constant contexts the compiler interprets its body.

Compile-Time Evaluation

const func Fib(n: int) -> int
{
    if n < 2
    {
        return n;
    }
    return Fib(n - 1) + Fib(n - 2);
}
 
const Answer: int = Fib(10);
const Greet: string = "con" + "stant";
 
func main() -> int
{
    print(Answer, Greet);
    return 0;
}

55 constant

Fib(10) is computed at compile time; Answer simply is 55. A const initializer can also reference earlier consts, and the compiler evaluates along the chain.