only expressions, no statements

acts as switch

i.e
val result = when(money) {
100 -> 'broke'
200 -> 'nice'
else -> 'idk'
}

i.e
fun(money: Int = 100) { ... }

can also be a function

single-expression functions

i.e
fun addByTwo(num: Int) = num + 2
fun isLoggedIn(username: String) = username.length > 0

complex logics

simple value manipuilation

paired with functional programming functions syntax

acts as an array

i.e
val myArray = listOf(1, 2, 3)

method of a list

does selection of elimination of a list

if it returns true, then it does not get eliminated

i.e
myArray.filter {
it <= 20
}

similar to javascript arrow functions

a variable holds an anonymous function

function that is an expression

can be passed as data

i.e
val myLambda: (Int) -> Int = {someInteger -> someInter - 20}