Variables.md

Variables (Jet » Design)

Overview

Variables are created with the let keyword. The type of the variable is inferred from the value assigned to it. The type can be also explicitly specified with the : [type] syntax.

fn main {
  let age: i32 = 1;
  let name = "Jet"; // inferred: str
}

Variables are immutable by default:

fn main {
  let age = 1;
  age = 2; // error
}

To create a mutable variable use a var keyword instead of let.

fn main {
  var age = 1;
  age = 2;
}

References

To reference an object, use the & symbol:

fn main {
  let age = 1;
  let age_ref = &age;
}

References behave like a non-null pointer equivalent in C++ with implicit dereference.

fn main {
  let age = 1;
  let age_ref = &age;
  println("Age: {}", age_ref); // prints "Age: 1"
}

References can be reassigned:

fn main {
  let x = 1;
  let y = 2;
  let r = &x;
  // rebind to y
  r = &y;
  println("Age: {}", r); // prints "Age: 2"
}