I've used Reactor and RxJava in pet projects. It was kind of great then, makes it possible to write Java in a very functional way. But the project I'm currently working on is a mess because people start using observables for everything. Also they would wrap imperative code in observables.

If you don't use them properly it becomes very unclear what part is lazy, and what not. And if some observables just return one values, or many, or many never stops. Also testing can be a bit difficult. Partly because of this, that are now building an API with spring boot (without reactor).

If you just put all your pure non-reactive functions in one packages. Combine them to some Io to reactive functions in another. And expose those functions with something like Vert.X could write some high quality and good maintainable Java code I think, but it takes some discipline.

👍 thanks for the insight @U26FJ5FDM