val upperIt2: (String) -> String = { s: String -> s.uppercase() + s.uppercase() } // Simplify things with it val upperIt3: (String) -> String = { it.uppercase() + it.uppercase() + it.uppercase() } fun upperIt3(s: String): String = s.uppercase() + s.uppercase() // Higher-order function as a parameter fun func3(s: String, func: (String) -> String): String = func.invoke(s) fun main() { println(func3("abc", upperIt2)) println(func3("table", upperIt3)) println(func3("house", ::upperIt3)) }