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kotlinlang

In swift, we can confirm to any protocol / interface using extensions. Can we add interface conformance to certain class using extension in Kotlin?

No, it’s not possible and probably will never be supported, because it wouldn’t work on JVM without some huge hacks and will anyway break compatibility with Java

sounds like traits in Rust!? I enjoy figuring out the difference between those and the interfaces I'm used to Java/Kotlin (apart from the obvious fact that interface extension can only happen while the extending class itselft is written. E.g. implementing traits not for a specific struct but for other traits.)
But yeah, in regards to the original question: that doesn't work in Kotlin.