🔍 Overview - Unit 7

The theme of this unit is “Composition.” We will explain a hierarchical and mathematically beautiful set of APIs for combining multiple Timelines to create a single new Timeline.

This Unit begins with combineLatestWith, the foundation of all composition. This is nothing other than a concrete implementation of the Applicative Functor we learned about in Unit 4.

Next, we will show how to scale this simple binary operation. The key to this is the algebraic structure known as a Monoid. You will witness how intuitive high-level APIs like andOf, orOf, and listOf are naturally derived from a single folding function, foldTimelines, and their respective Monoids.

Through this unit, you will move from the art of manipulating a single Timeline to acquiring the design philosophy of declaratively composing collections of Timelines to elegantly construct complex states.