To be accurate will find the ISO-8601 approach unsuitable.Ĭlass use of identity-sensitive operations (including reference equality However, any application that makes use of historical dates, and requires them System, in which today's rules for leap years are applied for all time.įor most applications written today, the ISO-8601 rules are entirely suitable. It is equivalent to the proleptic Gregorian calendar The ISO-8601 calendar system is the modern civil calendar system used today It cannot represent an instant on the time-line without additional information Instead, it is a description of the date, as used for birthdays. This class does not store or represent a time or time-zone. Other date fields, such as day-of-year,ĭay-of-week and week-of-year, can also be accessed.įor example, the value '2nd October 2007' can be stored in a LocalDate.

LocalDate is an immutable date-time object that represents a date, Likewise, if you have an immutable reference to a mutable thing, you’re ensuring not that the mutable thing won’t change, just that your immutable reference won’t ever point to anything but what you set it to.A date without a time-zone in the ISO-8601 calendar system, Any errors resulting from modification is up to the implementation it could be desired or not, it’s not the compilers concern.

Immutable ensures that while you may not get the exact thing you wanted, it will still be in the form of that thing as described - mutating an “immutable” list, you still have a list with all the bells and whistles of a list.

If you introduce bugs through modifying the thing, that’s an implementation detail, that’s up to the developer to ensure.

Now, in languages like Kotlin and Java, whatever you say the thing is, it is that thing. Some modern languages allow this too - Swift offers UnsafePointer, in which you tell it what that memory represents but it offers zero guarantees that’s actually what’s there. You can then pass that pointer around freely. In C, you can use void pointers like a magic bullet - it can point to anything. The purpose is to prevent the reference from being mutated. The goal isn’t to prevent modification, and mutable/immutable is more or less a misnomer. Lots of great explanations of why you can do it and not why the opposite exists - immutability.

Kotlin mutable list