Hello there, future coder! In this session, we will unravel function overloading in Scala. It's much like a multi-purpose gadget; it has different functionalities, all under one name. By the end of this lesson, you will have a firm understanding of what function overloading is, its purpose, and how to create overloaded functions in Scala. Ready? Let's get rolling!

Function overloading is akin to a chef crafting dishes with unique ingredient combinations — you use different ingredients (parameters), but the dish's name (function name) remains the same.

In Scala, function overloading allows us to define multiple functions with the same name but different parameters. There are three ways you can overload a function:

• By parameter types
• By the number of parameters
• By the order of parameters

Scala chooses the appropriate function to execute based on the type, number, or order of arguments, providing us with effective code organization and improved readability. Notably, overloaded functions cannot differ only by their return type. Now, let's dive into each of these types of overloading one by one!

Let's bring this concept to life.

Suppose we're developing an application for a display board. Sometimes we receive text to display (a String), and other times, a number (an Int).

def display(input: String): Unit =
  println(s"Calling display with String input: $input")

def display(input: Int): Unit =
  println(s"Calling display with Int input: $input")

@main def run: Unit =
  display("Hello, World!") // Prints "Calling display with String input: Hello, World!"
  display(12345) // Prints "Calling display with Int input: 12345"

Our function named display proved useful in both cases, with each function executing as intended. This is function overloading with different parameter types!

In another scenario, let's overload functions with varying numbers of parameters. If we want to add two or three numbers, we can define two add functions, each accepting a different number of parameters.

def add(num1: Int, num2: Int): Int =
  num1 + num2

def add(num1: Int, num2: Int, num3: Int): Int =
  num1 + num2 + num3

@main def run: Unit =
  println(add(1, 2))  // Calls first "add" function
  println(add(1, 2, 3)) // Calls second "add" function

Scala selects the correct overloaded function based on the number of arguments provided.