Mastering in Kotlin Generics and Variance

Kotlin is a modern programming language that offers powerful features for building robust and type-safe applications. One such feature is generics, which allows developers to write reusable code that can work with different types. In this blog post, we will delve into the concept of Kotlin generics and explore the intricacies of variance, providing clear explanations and practical examples along the way.

In Kotlin, there are some advanced concepts related to generics that we will explore. These concepts include reified type parameters and declaration-site variance. While they may sound unfamiliar, don’t worry! This blog post will cover them in detail.

Generic type parameters

In Kotlin Generics, you can define types that have type parameters, allowing for more flexible and reusable code. When you create an instance of such a type, you substitute the type parameters with specific types, known as type arguments. This allows you to specify the kind of data that will be stored or processed by the type.

For example, let’s consider the List type. In Kotlin, you can declare a variable of type List<String>, which means it holds a list of strings. Similarly, the Map type has type parameters for the key type (K) and the value type (V). You can instantiate a Map with specific arguments, such…