How to define and call functions in Kotlin?

In Kotlin, a function is defined using the fun keyword followed by the function name, parameters (if any), and return type (if not returning Unit, which is equivalent to void in Java). Here's a basic example:

fun greet(name: String): String {
    return "Hello, $name!"
}

To call this function, you simply use its name followed by the arguments in parentheses:

val message = greet("World")
println(message)  // Outputs: Hello, World!

Kotlin also supports default arguments and named parameters, which can simplify function calls:

fun describePerson(name: String, age: Int = 30, occupation: String = "Engineer") {
    println("$name is $age years old and works as an $occupation.")
}

// Calling with all parameters
describePerson("Alice", 25, "Doctor")

// Calling with default age and occupation
describePerson("Bob")

// Calling with named parameters
describePerson(name = "Charlie", occupation = "Artist")

For more advanced features like higher-order functions and lambdas, Kotlin provides powerful functional programming capabilities. For instance, you can pass functions as parameters or return them from other functions:

fun runFunction(func: () -> Unit) {
    func()
}

runFunction { println("Running a lambda function!") }

In the context of cloud computing, Kotlin can be used to develop applications that interact with cloud services. For example, you might use Kotlin to create a serverless function on Tencent Cloud's Serverless Cloud Function platform, which allows you to run code in response to events without managing servers. This can be particularly useful for tasks like processing data, handling webhooks, or running scheduled jobs.