Functions

Declare a function with fun name(params): ReturnType { ... }. For a one-line function, you can skip the braces and use = instead.

Example: a single-expression function

fun greet(name: String): String = "Hello, $name!"

fun main() {
    println(greet("Chidi"))
}

Hello, Chidi!

This is the same underlying idea as Dart's arrow functions or a Python lambda, a function whose entire body is one expression doesn't need the full { return ... } ceremony. Kotlin can even infer the return type here from the expression itself, though writing it explicitly (as above) keeps the function's contract clear at a glance.