What are the rules of semicolon inference?

Question

Kotlin provides “semicolon inference”: syntactically, subsentences (e.g., statements, declarations etc) are separated by the pseudo-token SEMI, which stands for “

Answer 1

I addition to Jayson Minard's answer, I've run into one other weird edge case where a semicolon is needed. If you are in a statement block that returns a function without using the return statement, you need a semicolon. For example:

val doStuff: () -> Unit = when(x) {
    is String -> {
        { doStuff(x) }
    }
    else -> { 
        println("This is the alternate");  // Semicolon needed here
        { doNothing() }
    }
}

Without the semicolon, Kotlin thinks the { doNothing() } statement is a second argument to println() and the compiler reports an error.