(MPP newbie here, so if there's a resource I'm missing that answers my questions, please let me know) Is there no way to have a default method implementation in an expect class?

expect class Grade : Comparable<Grade> {
    val rough: Int
    val fine: Int

    // Apparently I can't implement this here
    override fun compareTo(other: Grade) {
        var result = rough.compareTo(other.rough)
        if (result == 0) result = fine.compareTo(other.fine)
        return result
    }
}

You can do

expect class Grade : GradeInterface

where

GradeInterface

has your default implementations

Hmm, interesting. Thanks for the info.

There's also https://youtrack.jetbrains.com/issue/KT-20427 around this functionality