Variables

<type> <name> = <value>;

All variables are constant and immutable by default

int a = 1;
a = 2; // Error

To make a variable mutable, you can add the mut keyword

mut int b = 2;
b = 3; // Works!

Shadowing

You can redefine variables with the same name within the same or lower scopes using shadowing, including changing the mutability of the variable.

int a = 10; // lets call this `a_1`

// change mutability of a
mut int a = 20; // different variable from `a_1`, let's call this `a_2`

// change type of a
str a = "hi"; // different variable from `a_1` and `a_2`, let's call this `a_3`

// redeclare within a lower scope
{
  str a = "annyeonghaseyo"; // different from `a_1`, `a_2`, and `a_3`, let's call this `a_4`
}

// `a_4` is no longer available, we're back to `a_3`
assert(a == "hi");