Circuit – A Compose-driven architecture for Kotlin and Android applications

Circuit is a simple, lightweight, and extensible framework for building Kotlin applications that’s Compose from the ground up.

Compose itself is essentially two libraries – Compose Compiler and Compose UI. Most folks usually think of Compose UI, but the compiler (and associated runtime) are actually not specific to UI at all and offer powerful state management APIs.

It builds upon core principles we already know like Presenters and UDF, and adds native support in its framework for all the other requirements we set out for above. It’s heavily influenced by Cash App’s Broadway architecture (talked about at Droidcon NYC, also very derived from our conversations with them).

Circuit’s core components are its Presenter and Ui interfaces.

1. A Presenter and a Ui cannot directly access each other. They can only communicate through state and event emissions.
2. UIs are compose-first.
3. Presenters are also compose-first. They do not emit Compose UI, but they do use the Compose runtime to manage and emit state.
4. Both Presenter and Ui each have a single composable function.
5. In most cases, Circuit automatically connects presenters and UIs.
6. Presenter and Ui are both generic types, with generics to define the UiState types they communicate with.
7. They are keyed by Screens. One runs a new Presenter/Ui pairing by requesting them with a given Screen that they understand.

Circuit’s repo is being actively developed in the open, which allows us to continue collaborating with external folks too. We have a trivial-but-not-too-trivial sample app that we have been developing in it to serve as a demo for a number of common patterns in Circuit use.

Circuit on GitHub: https://github.com/slackhq/circuit
Web-site: https://slackhq.github.io/circuit/
Platform: Android
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