// Created on savesnippets.com · https://savesnippets.com/DJ4kYm7Ms4SOzx
@JvmInline value class UserId(val raw: Long)
@JvmInline value class PostId(val raw: Long)
@JvmInline value class Email(val raw: String) {
    init { require(raw.contains("@")) { "not an email: $raw" } }
    val domain: String get() = raw.substringAfter("@")
}

fun deleteUser(id: UserId) { println("deleting user ${id.raw}") }

fun main() {
    val u = UserId(42L)
    val p = PostId(99L)

    deleteUser(u)             // ✓
    // deleteUser(p)          // ✗ compile error — different types
    // deleteUser(42L)        // ✗ compile error — Long isn't UserId

    val e = Email("alice@example.com")
    println(e.domain)         // example.com

    // At runtime, UserId is just a Long — zero memory overhead vs raw Long.
}