I'm pretty sure it's the JVM model. Kotlin collections are "immutable" in that they have no mutating accessors, which is not the same thing as a memory region d

I'm pretty sure it's the JVM model. Kotlin collections are "immutable" in that they have no mutating accessors, which is not the same thing as a memory region defined to be immutable by the specification which can be relied on to e.g. trivialize certain compiler optimizations. (I plead ignorance about Kotlin Native, maybe it does such things.) You can also look at what kinds of things are allowed in class constant pools; you will not find any collections. https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html#jvms-4.4 https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.ht...