Modeling States and Structure

The benefits of using types to represent the states and shapes of your entities, and how it makes your code safer, more expressive and easier to maintain.

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THE CURRENT VERSION OF THIS ARTICLE IS PUBLISHED HERE.

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Tags: #FUNDAMENTAL CONCEPT

This article is part of the Kotlin Primer, an opinionated guide to the Kotlin language, which is indented to help facilitate Kotlin adoption inside Java-centric organizations. It was originally written as an organizational learning resource for Etnetera a.s. and I would like to express my sincere gratitude for their support.

It is recommended to read the Introduction before moving on. Check out the Table of Contents for all articles.

In the previous chapter, we discussed how sealed hierarchies could be used to model illegal states (such as invalid data), thereby recovering the ability to reason locally, achieve linear code flow, prevent certain types of errors from ever happening, increase readability and maintainability, and communicate and enforce assumptions explicitly.