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Kotlin Lambdas and Higher-Order Functions

Kotlin Lambdas and Higher-Order Functions

Learn about Kotlin functions, lambdas, and higher-order functions.

We'll cover the following...

Functions

Kotlin uses the keyword fun to declare functions, which can take parameters and return values. Here’s an example of declaring a function in Kotlin:

Kotlin
fun main(){
    greet("Adam", "evening")
}
fun greet(name : String, timeOfDay : String) {
    println("Good $timeOfDay, $name!")
}

In the code above, we declare a greet function which takes two parameters: name and timeOfDay. The function prints a message to the console that includes both parameters.

Function return types

We can also define a return type for a function, which specifies the type of value the function returns. We define the return type after the parameter list, using the colon notation. Here’s an example of a function that returns a string:

Kotlin
fun main(){
    print(getGreeting("Adam", "evening"))
}
fun getGreeting(name : String, timeOfDay : String) : String {
    return "Good $timeOfDay!, $name."
}

In the code above, we define a getGreeting function that takes two parameters, name and timeOfDay, to return a ...