def printName(first: String, last: String): Unit = {
  println(first + " " + last)
}

printName("John", "Smith")  // Prints "John Smith"
printName(first = "John", last = "Smith")  // Prints "John Smith"
printName(last = "Smith", first = "John")  // Prints "John Smith"

printName(last = "Smith", "john") // error: positional after named argument