RxDart
The Reactive Extensions for Dart
...By emphasizing immutability and one-way data flow, RxDart helps isolate side effects and makes complex state transitions easier to reason about. It’s widely used to coordinate UI events, network requests, and caching layers, especially when timing and concurrency are non-trivial. The library aims to stay idiomatic with Dart Streams while giving developers the ergonomic power long associated with the ReactiveX family. In practice, it encourages clear separation between data producers, transformers, and consumers.