We can go further with arguments by naming them or setting default parameter values.

To improve the readability of our code, we can name our arguments when invoking the function. For example, with our calculateForce() function, we can add the names of arguments to our function call:

fun calculateForce(mass: Int, acceleration: Int) {
  var force = mass * acceleration
  println("The force is $force Newtons.")
}

fun main() {
  // Invoke the function with named arguments.
  calculateForce(acceleration = 12, mass = 5) 
  // Prints: The force is 60 Newtons.
}

Note that by naming our arguments when we invoke a function, we do not need to place the arguments in the same order as they appear in the function header.

Default arguments provide values to function arguments if none are given when the function is called. To implement this, we add an assignment operator and a value after the argument in the function header, like so:

fun greetCustomer(name: String = "Customer") {
  println("Hello, $name.")
}

In the greetCustomer() function, we set the default value of the argument name to "Customer".

If we invoke this function with a String value, that value will become the value of name; however, if no argument is given, name will have a value of "Customer":

greetCustomer("Cynara") // Prints: Hello, Cynara.
greetCustomer() // Prints: Hello, Customer.