lambdas and higher-order functionshttps://developer.android.com/codelabs/kotlin-bootcamp-functions#6

LambdasAndHighOrderFun.kt

fun main() {
    var dirtyLevel = 30
    val waterFilter: (Int) -> Int = { dirty: Int -> dirty / 2 }
    println(waterFilter(dirtyLevel))

    println(updateDirty(dirtyLevel, waterFilter))

    println(updateDirty(dirtyLevel, ::increaseDirty))

    dirtyLevel = updateDirty(dirtyLevel) { it + 23 }

    println(dirtyLevel)
}

fun updateDirty(dirty: Int, operation: (Int) -> Int): Int = operation(dirty)

fun increaseDirty(start: Int) = start + 1