State Matters

Any decent-sized client side application quickly develops specific requirements and business logic that cannot be tossed over the fence into the backend.

• Form Validation
• Cart Management
• User grant enforcement

Redux the initial engineering mistake has been supplanted by hooks; but the gains in speed meant losses in testability and control over form and content of data.

Typescript does its best at enforcing tactical control over values, but is not adequate for managing strategic management of values (buy two get one free, max 1 per customer, passwords must match).

State systems that do not actively model structure and form abdicate the responsibility for control over activity and their own content, and that, in my mind, is a copout.

Forest is an attempt to make a strong capable state system that can be used locally or globally, has the capacity for extremely strong type and context-aware constraints, is fault tolerant, and gives the user the ability to write deep, nested mutators. It is highly influenced by RxJS and Immer (and uses both of those libraries) and promotes view-independent testing.

Forest uses a series of nested "Leafs", or nodes, to represent complex states; they can be nested as deep as necessary to give control context to the system. Mutator actions can be written relative to whichever Leaf contains the information they need to execute, and changes in child Leafs percolate to the parent.

Leaf broadcasts to view contexts via RxJS observers. Each Leaf (or the root Leaf) can be monitored for changes.