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kotlinlang

Is there a list of requirements somewhere for a "proper" collection implementation? I seem to remember all collections must implement `equals` and `hashCode` in a certain way to ensure they can all be compared with each other, but I don't know where that exactly is specified

Requirements for Kotlin collection interfaces (Collection, List, Set, Map and their mutable counterparts) are currently on internal review.

Meanwhile, you can check contracts for similar Java collections (like <https://docs.oracle.com/javase/8/docs/api/java/util/List.html>).