Partial is now available in its own Swift package on GitHub. This post is still valid, but somewhat out of date.
Structs are incredibly useful in Swift, especially when representing static read-only data. However, the values of a struct often come from multiple sources, such as view controllers, network requests, and files on disk, which can make the creation of these structs cumbersome.
There are numerous methods to work around this, but each have their downsides. One of these methods is to change the struct to a class and update the properties to vars, but this removes the advantages of read-only structs. Another is to make a "builder" object, but the API of this object must be kept in-sync with the object is wraps.
Partial eliminates these problems by providing a type-safe API for building structs by utilising generics and
KeyPaths. Although I learned of the concept of
Partial through TypeScript – which [provides
Partial as a built-in type] – the Swift implementation supports many more use cases.