KotlinでScala3のContextual Abstractionsみたいなもの

ContextualAbstractions.kt

// 下記の記事の最後のコード例をKotlinで書いてみた
// https://zenn.dev/hinastory/articles/c8d5267ea43ed6

package hello.kotlin

data class Person(val name: String, val age: Int)
data class Japanese(val name: String, val age: Int, val info: String)

interface CanGreet<T> {
	fun T.hello()
}

object PersonCanGreet: CanGreet<Person> {
	override fun Person.hello() = println("hello!")
}

object JapaneseCanGreet: CanGreet<Japanese> {
	override fun Japanese.hello() = println("こんにちは。実はわたしは、${info}なんです。")
}

context(CanGreet<T>)
fun <T> greeting(a: T) = a.hello()

fun main() {
	val alexa = Person("Alexa", 12)
	val hanako = Japanese("Hanako", 18, "テニスが趣味")
	with(PersonCanGreet) {
		with(JapaneseCanGreet) {
			greeting(alexa)
			greeting(hanako)
		}
	}
}