What Is Kotlin?

// Hello World in Kotlin
fun main() {
    println("Hello, Kotlin!")
}

// Top-level functions, no class wrapper needed
fun greet(name: String): String {
    return "Hello, $name!"
}

// Single-expression function shorthand
fun square(x: Int) = x * x

// String templates with expressions
fun describe(n: Int): String {
    return "The square of $n is ${square(n)}"
}

fun main2() {
    val message = greet("World")
    println(message)
    println(describe(5))

    // Type inference
    val language = "Kotlin"   // inferred as String
    var version = 2.0         // inferred as Double
    version += 0.1

    println("$language $version")
}