Kotlin Programming: The Big Nerd Ranch Guide, 2nd Edition

Lambda Expressions

In your NyetHack project, create a new file called Narrator.kt to host your narrator and its moods. For now, your narrator will only have one mood: loud. Create a new function called narrate and implement it by defining a lambda expression, calling it, and printing the result:

Listing 8.3  Defining a lambda expression (Narrator.kt)

fun narrate(
    message: String
) {
    println({
        val numExclamationPoints = 3
        message.uppercase() + "!".repeat(numExclamationPoints)
    }())
}

Just as you write a string by putting characters between opening and closing quotes, you write a function by putting an expression or statements between opening and closing curly braces. Here, you begin with a call to println. Inside the parentheses ...