layout: series_index
title: “Recursive types and folds”

seriesIndexId: “Recursive types and folds”

In this series, we’ll look at recursive types and how to use them, and on the way, we’ll look at
catamorphisms, tail recursion, the difference between left and right folds, and more.

• Introduction to recursive types. Don’t fear the catamorphism….
• Catamorphism examples. Applying the rules to other domains.
• Introducing Folds. Threading state through a recursive data structure.
• Understanding Folds. Recursion vs. iteration.
• Generic recursive types. Implementing a domain in three ways.
• Trees in the real world. Examples using databases, JSON and error handling.