We build an experimental data type that combines the advantages of both structs and classes. It allows shared mutable state while preserving the features of structs to make easy copies and observe changes.
We build upon the Future type of a previous episode to implement a simple reactive library. Along the way, we dive into debugging a reference cycle in our implementation.
We extend the networking code from the first episode to support POST requests. Besides using Swift's enums with associated values and generics, we get to implement a map function on a custom data type.