> By default, variables are mutable. You can enable Immutable by Default mode using a directive.
> //> immutable-by-default
> var x = 10; > // x = 20; // Error: x is immutable
> var mut y = 10; > y = 20; // OK
Wait, but this means that if I’m reading somebody’s code, I won’t know if variables are mutable or not unless I read the whole file looking for such directive. Imagine if someone even defined custom directives, that doesn’t make it readable.