Scala中更好的函数输入/输出参数样式

def add(a: Int, b: Int): Int = {
  return a + b
}

def add(a: Int, b: Int): Int = a + b

def greet(firstName: String, lastName: String): Unit = {
  println(s"Hello, $firstName $lastName!")
}

greet(lastName = "Smith", firstName = "John")

def greet(name: String, greeting: String = "Hello"): Unit = {
  println(s"$greeting, $name!")
}

greet("John")           // 输出：Hello, John!
greet("Alice", "Hi")    // 输出：Hi, Alice!

def sum(numbers: Int*): Int = {
  numbers.sum
}

sum(1, 2, 3)     // 输出：6
sum(4, 5, 6, 7)  // 输出：22