Magic Boxes, Functions

In Kotlin, functions start with the fun word fun.

Create a function

fun sayHello() {
    println("Hello!")
}

fun main() {
    sayHello() // use it
}

Ingredients and results

When you pass ingredients into a function, you put them in ( ), and you also tell Kotlin the output type.

fun add(a: Int, b: Int): Int {
    return a + b
}

fun main() {
    val result = add(10, 20)
    println(result)
}

Translation:

Define a fun magic box called add (ingredients are numbers a and b): (output will be a number) {
    return a + b
}

One-line magic

If a function is simple, Kotlin lets you write it in one line.

fun multiply(a: Int, b: Int) = a * b

Short and sweet. That is why Kotlin developers can handle complex tasks with joy.