javelin VS subscriptions

An aspect that flex has that is important when using it with UI frameworks is the ability to control when to start listening to something and when something updates. This is why it differentiates between "signals," which are pure calculations that are inert unless actively being listened to, and "effects" which do side effects and can be started/stopped. In React and other GUI frameworks, you need to be able to abide by the lifecycle of the framework, which means you may need to wait to start running updates until the component your effect is used in has actually appeared in the UI. This is provided by effect and listen returning a function that, when called, starts listening and calling the return value of that stops. Javelin does not give you quite this much control; defc= is eager and will start listening and updating immediately. See https://github.com/hoplon/javelin/issues/27 for their discussion about this very topic.

I asked around and there is another option. Something called "Incremental Computations". Here is a Clojure library. I think the examples kinda demo how it works

https://github.com/hoplon/javelin

The subscriptions library is designed to delegate to reagent and has a clojure implementation here which is not reactive right now. It should be straightforward to substitute in the posh implementation in that namespace and achieve parity with cljs. There are already working test cases in clojure for computing derived values here. If you want to take a shot at that I would welcome a PR :D

I have been iterating on new features of my subscriptions library (originally extracted from re-frame) https://github.com/matterandvoid-space/subscriptions and have some major additions: