The biggest difference is in how the state is managed. With OOP, each class is typically its own state machine with its internal behavior. With the FP approach,

The biggest difference is in how the state is managed. With OOP, each class is typically its own state machine with its internal behavior. With the FP approach, you can treat your state like a database, and you can easily inspect the overall state of the application. There is some nice tooling for doing these kinds of inspections in re-frame nowadays https://github.com/Day8/re-frame-10x https://github.com/Day8/re-frame-10x