We have already mentioned that, in Scala, objects are immutable. You can, of course, make sure that a specific class has its fields declared as vars, but this is discouraged and considered bad practice. After all, immutability is good and we should try to aim for it.
The lens design pattern was created specifically for that purpose and allows us to overcome the immutability limitation and at the same time preserve the code's readability. In the following subsections, we will start with some code that doesn't use the lens design pattern and we will go step by step to show how to use it and how it improves our applications.