Functions

To define a function in Kotlin, you have to use the fun keyword, as follows:

fun firstClass() {
    println("First class function")
}

The preceding snippet demonstrates that we can declare functions as first class citizens. We can also define functions as class members, as follows:

class A {
    fun classMember() {
        println("Class member")
    }
}

A local function is a function that is declared in another one, as follows:

fun outer() {
    fun local() {
        println("Local")
    }
    
    local()
}

In the preceding snippet, the local function is declared inside of the outer function. The local functions are only available in the scope of a function where they were declared. This approach can be useful if we want to avoid duplicate code inside of a function.

This section will cover the following topics:

• Functional programming
• Higher-order...