fun createUser(
    name: String,
    role: Role = Role.MEMBER,
    email: String? = null,
) = transaction {                       // trailing lambda
    val user = Users.insert(name, role, email)
    if (email != null) {                // smart cast: email is now String
        sendWelcome(email.lowercase())
    }
    user
}
 
createUser(name = "Anton", role = Role.ADMIN)   // named args + default

<build>
    <plugins>
         <plugin>
             <groupId>org.jetbrains.kotlin</groupId>
             <artifactId>kotlin-maven-plugin</artifactId>
             <version>2.3.20</version>
             <extensions>true</extensions> <!-- Add this extension  -->
         </plugin>
    </plugins>
</build>

<project>
    <properties>
        <!-- Disable smart defaults via property -->
        <kotlin.smart.defaults.enabled>false</kotlin.smart.defaults.enabled>
    </properties>
</project>

data class User(val username: String, val email: String)
 
fun main() {
    val user = User("alice", "alice@example.com")
 
    val (email, username) = user
 
    println(email)
    // alice
 
    println(username)
    // alice@example.com
}

fun main() {
    val user = User("alice", "alice@example.com")
 
    // Uses name-based destructuring with explicit form
    (val mail = email, val name = username) = user
 
    println(name)
    // alice
 
    println(mail)
    // alice@example.com
}

@OptIn(ExperimentalStdlibApi::class)
fun main() {
    val map = mutableMapOf(1 to 1, 2 to 2, 3 to 3, 4 to 4)
 
    val toRemove = map.entries
        .filter { it.key % 2 == 0 }
        .map { it.copy() }
 
    map.entries.removeAll(toRemove)
 
    println("map = $map")
    // map = {1=1, 3=3}
}

devServer = (devServer ?: KotlinWebpackConfig.DevServer()).apply {
    static = (static ?: mutableListOf()).apply {
        add(project.rootDir.path)
    }
}

config.watchOptions = config.watchOptions || {
    ignored: ["**/*.kt", "**/node_modules"]
}
 
if (config.devServer) {
    config.devServer.static = config.devServer.static.map(file => {
        if (typeof file === "string") {
        return { directory: file,
                 watch: false,
        }
    } else {
        return file
    }
    })
}

kotlin {
    wasmJs {
        ...
        compilerOptions {
            freeCompilerArgs.add("-Xwasm-kclass-fqn")
        }
    }
}