Default arguments

Default values to the arguments is a nice way for an API to evolve. If we already have a function with two arguments and we need a third argument, we can make the transition easy by making use of default values to arguments. The existing code still works and, at the same time, we can invoke a function with new arguments. Default values to arguments make the API simple and expressive. 

Let's write an example to provide a default value to an argument to the function.

Consider the code for 6e_DefaultArguments.kts:

fun welcome(name: String, msg:String = "Hey") {
    println("$msg $name")
}
welcome("Bob", "hello")
welcome("Berry")

In this case, we are not providing the second argument, msg, to the welcome() function. It therefore uses a default message instead. The output is as follows:

As shown in the preceding example, a default value to an argument can be specified with an = symbol in the argument declaration. In this case, if we don't pass the second argument while invoking the function, a default value will be provided.