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Comment by ragnese | Hacker News Reader

If I remember correctly, it's fairly easy to use @Nullable and still end up with nulls there, even without an IDE warning. I'll have to double check to see if I can still reproduce that.

But, to be fair, it's actually fairly easy to break Kotlin's null safety, too: https://blog.haroldadmin.com/circular-refs-kotlin/

But I basically agree with what you've said. Kotlin is certainly still a much more ergonomic language, but Java caught up fast recently.

Kotlin 1.5 will be really cool, though, with the new value classes and the mutable methods feature (stolen from Swift).

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Value classes cannot provide the performance/memory flatness that Valhalla will bring though. So I'm not really sure what benefit does "values classes" bring. Just to make sure, you are talking about the inline class which is just a wrapper around single property?

   inline class Password(val value: String)

Yes and no: https://github.com/Kotlin/KEEP/blob/master/notes/value-class...

"value class" is the next step for inline classes. They are going to behave very much like Swift's struct and its "mutating methods". And they are going to be "Valhalla ready" so we'll get the performance improvements automatically when it lands.

In a sense, they are an upgraded data class with a much more precise and controlled form of mutation. Rather than a `var` field meaning the object will mutate in-place, it will basically automatically call a kind of (implicit) "copy()" method. Further, you may only mutate these `var` fields inside of class methods that are marked with a new keyword: `mutating`.

Read through the KEEP. It's pretty interesting stuff. At first it kind of rubbed me the wrong way, but the more I thought about it, the more excited I got about it- especially after thinking about how Swift does it and it works well there.

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