TransformationFunctionsExample.kt

data class Address(var addressLine1: String, var city: String)
data class Person(var name: String, var address: Address)

fun main() {
    // map
    val listOfPeople = listOf<Person>(
        Person("Jane", Address("Manjalpur", "Vadodara")),
        Person("John", Address("Vastrapur", "Ahmedabad")),
        Person("Bob", Address("Bandra", "Mumbai"))
    )

    val people = listOfPeople.map { it.name to it.address.city }
    print("List of Pair of each person and their city = $people")

    // flatmap
    val listOfMumbaiPeople = listOf<Person>(
        Person("John", Address("Thane", "Mumbai")),
        Person("Bob", Address("Bandra", "Mumbai"))
    )
    val listOfVadodaraPeople = listOf<Person>(
        Person("Jane", Address("Manjalpur", "Vadodara")),
        Person("Alice", Address("Akota", "Vadodara"))
    )

    val allPeople = listOf(listOfMumbaiPeople, listOfVadodaraPeople)
    val names = allPeople.flatMap { it.map { it.name } }
    print("\nAll names from all lists = $names")

    // flattten() - combine list of lists into one single list
    print("\nSingle list of all people = ${allPeople.flatten()}")
}