I found a LLM prompt that gives (in my attempts) consistently super rubbish nonsense results: ```in...

# random

[Paul Woitaschek]

I found a LLM prompt that gives (in my attempts) consistently super rubbish nonsense results:

in kotlin: is x as? Y and x as? Y? always the same?

[Youssef Shoaib [MOD]]

I'm scared of getting this question wrong cuz I should know the answer lol, but they are the same, right? Safe casting means that you return null if the value doesn't match the type, so if x is null, the first one returns null as a result of that, and the second one passes the cast (because the type is nullable) and thus also gives you null.

[Paul Woitaschek]

Yep I think so too and couldn’t find any example that proves otherwise

[Paul Woitaschek]

Yes I think that's the correct explanation.
I think this is fundamentally hard to understand because of type erasure.
Once it's null, the runtime doesn't know if it's a null Person or a null Pet

[CXwudi]

Is it correct? From `gpt-4o-2024-08-06`:

---

No, x as? Y and x as? Y? are not always the same in Kotlin.

- x as? Y attempts to cast x to a non-nullable type Y. If x is not an instance of Y, it returns null.

- x as? Y? attempts to cast x to a nullable type Y?. This means x can be null or an instance of Y. If x is not an instance of Y or null, it returns null.

The difference lies in the type you are trying to cast to: Y is non-nullable, while Y? is nullable.

[Paul Woitaschek]

That's not really an answer. It could also say: its not the same as one has a ? and the other doesn't.
Ask it to give an example where they are not the same