Exploring Higher Order Functions in Kotlin

What Are Higher Order Functions in Kotlin?

Kotlin is an increasingly popular language for Android development, and higher order functions are an important part of the language. Higher order functions are functions that take other functions as arguments, or return a function as a result. This post will explore what higher order functions are, and how they can be used to write better code in Kotlin.

What are Higher Order Functions?

Simply put, a higher order function is any function that takes one or more other functions as arguments, or returns a function as a result. Higher order functions can access the parameters of the functions that are passed in, and can modify them as needed. These functions are incredibly powerful; they enable us to create code that is concise and maintainable, and encourages functional programming principles.

Let’s take a look at an example to illustrate how higher order functions work. Suppose we have a function that takes two numbers and multiplies them together:

fun multiply(x: Int, y: Int): Int {
    return x * y
}

We can use this function within higher order functions. For example, we can create a function that takes two functions as parameters, applies each one to its argument, and then multiplies the results together. Here’s how it would look in Kotlin:

fun higherOrder(f1: (Int) -> Int, f2: (Int) -> Int): Int {
    return f1(2) * f2(2)
}

This higher order function takes two functions as parameters, and uses them to calculate the result. We can then pass in our own functions to this higher order function, like so:

val result = higherOrder(::multiply, { x -> x * x })
// result is 8

The first parameter passed to higherOrder() is multiply(), which takes two integers and returns the result of their multiplication. The second parameter is an anonymous function that takes an integer and squares it. The result is 8, since 2*2*2*2 = 8.

Benefits of Using Higher Order Functions

Using higher order functions has many benefits. First and foremost, it makes code more succinct and easy to read. For example, we could use our higherOrder() function from earlier to calculate the result of a set of operations on a single argument without having to define multiple functions:

val result = higherOrder({ x -> x * x }, { x -> x * 3 })
// result is 18

By using higher order functions, we can also create more modular and reusable code. In the above example, we could easily write a higher order function that takes an arbitrary number of functions and combines their results, reducing the need to repeat code.

Conclusion

Higher order functions are a powerful tool in Kotlin, enabling developers to write cleaner, more concise code. They allow us to write functions that are more reusable and modular, and encourage us to think about our code from a functional programming standpoint. With the right combination of higher order functions, you can create powerful and efficient applications that are easier to maintain and debug.