Kotlin Lambda

We can use lambda expressions to create a shortened function in Kotlin. It is a type anonymous function.

Lambda syntax is

val lambdaname = {arg1 -> expression, ... argn -> expression}

Example of a lambda in Kotlin
In the following example, we created a lambda expression to print a Hi message, and we used that to print a couple of messages.

fun main(args: Array<String>)
{
	val sayHi = { x: String -> print("Hi $x\n")}
    sayHi("Mugambo!")
    sayHi("Kush Hua!")
}

Output:
Hi Mugambo!
Hi Kush Hua!

Lambda Expressions in filter
Let us see another example of lambda in action. Let's say I have an Array of country names.
I only want those countries which start with U.
We can use filter function in Array with lambda as given below.

fun main(args: Array<String>)
{
    var countryNames: List<String> = arrayListOf("United States", "United Kingdom", "India")
    println("Before Filter: ")
    println(countryNames)
    
	var countryNamesFilter: List<String> = countryNames.filter { s -> s.startsWith("U") }
    
    println("After Filter: ")
    println(countryNamesFilter)
}

Output:
Before Filter:
[United States, United Kingdom, India]
After Filter:
[United States, United Kingdom]