alt Hacker News> They have added proper algebraic data types to the language
No they haven't. E.g. they added a class that superficially looks like Option but subtly breaks the rules that Option is meant to follow, ensuring that no-one can ever manage to migrate existing codebases away from using `null`.
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_kidlike • today at 8:52 AM
optional is not how algebraic data types are implemented in Java. Basically it's the combination of sealed types and records.
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Sealed classes/interfaces and records are proper sum and product types.
The stdlib's Option type predates this language update by a long shot, so it doesn't use sealed classes, but it is now possible to have the usual FP "Maybe" type in Java:
``` sealed class Maybe<T> permits Some, None { record Some<T>(T obj) {} record None() {} } ```
(You will probably have to write Maybe.Some and I might have messed up the generic syntax as I wrote it on my phone, but that's mostly how it looks)