Higher-order functions in Kotlin

manish choudhary

2 April 2018

In this blog we are going to cover higher-order functions in kotlin with example. Higher order function can be passed as a parameter or can be returned from a function, the function which does the same is known as a higher-order function. In other words, a higher-order function is a function that takes functions as parameters or returns a function.

What is a Higher Order Function?

A higher-order function is a function that can take other functions as parameters and returns other functions.

How to create a Higher Order Function?

You can create a higher order function like any other function in Kotlin, but you need to create an parameter that has a function as the type.

Let’s take an example:

val repeat: String.(Int) -> String = { times -> repeat(times) }
val twoParameters: (String, Int) -> String = repeat // OK

fun highOrderFunctionCall(f: (String, Int) -> String): String {
    return f("hello", 3)
}
val result = highOrderFunctionCall(twoParameters)

val repeat: String.(Int) -> String = { times -> repeat(times) }

val twoParameters: (String, Int) -> String = repeat // OK

fun highOrderFunctionCall(f: (String, Int) -> String): String {

return f("hello", 3)

}

val result = highOrderFunctionCall(twoParameters)

OUTPUT: hellohellohello

Here, highOrderFunctionCall() is a function which take twoParameters() function as parameter.