Declaring variables

Variables are immutable by default at the time of their declaration. To mark a variable as mutable, use the mut keyword.

To declare a variable, simply use the val keyword, like so:

pub fn main() void = {
    val x = 10
    @print("{d}", {x})
}

We use the variable in this program through the use of the @print builtin, as unused variables in Spectre are a hard compile time error.

To give a type to the variable explicitly, do the following:

val x: i32 = 10

This particular example asserts to the compiler that the numerical value is a 32-bit signed integer.

Mutable values can be declared through the use of mut, as aforementioned:

val x: mut i32 = 10

Note that mut is part of the type name, making it easier to pass around values with knowledge of their mutability status.

Variables that are marked as mutable and are not mutated will result in a hard compile time error.