type aliases in Kotlin

In Kotlin, type aliases are essentially nicknames you give to existing types. They don’t create new types, but rather provide a more descriptive or concise way to refer to them.

Here are some key points about type aliases:

• Readability: They can improve code readability, especially when dealing with long or complex types. For example, instead of writing HashMap<String, ArrayList<Int>>, you could define a type alias like ShoppingList for better clarity.
• Context: Type aliases can add context to a type, making the code more self-explanatory. For instance, typealias CreditCard = String clarifies that a string variable represents a credit card number.
• Generic Types: They can be particularly useful for shortening lengthy generic types. Imagine a Set<Network.Node>, you could define a type alias like NodeSet for a more manageable name.

Here’s an example to illustrate:

typealias Username = String

fun registerUser(username: Username, password: String) {
  // ... perform registration logic ...
}

val myUsername = "Bard"
registerUser(myUsername, "s3cr3tp@ssw0rd")

In this example, Username is a type alias for String. It makes the code more readable and conveys the specific purpose of the string variable.

Remember:

• The compiler rewrites type aliases to their underlying type when processing the code.
• They are not new types, but simply alternative names.