let, also dan run dengan Penerima Boleh-Nol

fun main() {
    val name: String? = null
    val result = name?.let {
        println("never printed")
        it.length
    }
    println(result) // null
}

fun main() {
    val raw: String? = "  hello "
    val cleaned = raw?.let { it.trim().uppercase() } ?: "(empty)"
    println(cleaned) // HELLO
}

fun main() {
    val name: String? = "Alice"
    val len = name?.also { println("Processing: $it") }?.length
    println("len = $len")
}

fun main() {
    val items: List<Int>? = listOf(1, 2, 3)
    items?.also { println("Got list of size ${it.size}") }
           ?.forEach { println(it) }
}

fun main() {
    val name: String? = "Kotlin"
    val info = name?.run {
        "len=$length upper=${uppercase()}"
    }
    println(info)
}

class User(val name: String, val age: Int)
fun main() {
    val user: User? = User("Ada", 35)
    user?.let { "${it.name} age ${it.age}" }.also(::println)
    user?.run { "$name age $age" }.also(::println)
}

fun main() {
    val raw: String? = "  hello  "
    val result = raw
        ?.also { println("raw: '$it'") }
        ?.let { it.trim() }
        ?.also { println("trimmed: '$it'") }
        ?.uppercase()
    println(result) // HELLO
}

fun main() {
    val name: String? = "Kotlin"
    name?.takeIf { it.length > 3 }
        ?.let { println("Long name: $it") }
}

fun main() {
    val name: String? = "Alice"
    // OLD WAY:
    if (name != null) {
        val upper = name.uppercase()
        println(upper)
    }
    // NEW WAY:
    name?.let { println(it.uppercase()) }
}