Constants ========= {{#include ../links.md}} Constants can be defined using the `const` keyword and are immutable. Constants follow the same naming rules as [variables]. ```rust const x = 42; print(x * 2); // prints 84 x = 123; // <- syntax error: cannot assign to constant ``` Constants must be assigned a _value_, not an expression. ```rust const x = 40 + 2; // <- syntax error: cannot assign expression to constant ```