Composable Native APIs

Staltz sees React Native as a way to combine ideas from web and native development, with JavaScript reshaping how mobile apps are built. He argues that its challenges extend beyond rendering, state, routing, and requests because teams also work across native APIs, languages, and tools.

React makes rendering declarative, but APIs such as vibration, toasts, the clipboard, and text-to-speech often require imperative calls. Putting those calls in component lifecycle hooks or action creators works, Staltz says, but couples reusable components to singleton services.

Staltz defines composability with a practical test: a component should be useful when moved into its own package and imported elsewhere. His approach has components send requests upward, while singleton drivers handle the real effects, such as triggering vibration. This also allows apps to intercept requests and lets tests check events without a device or emulator.

Staltz describes bottom-up design as building from leaf components without needing to redesign them as the app grows. In Cycle.js, components follow the same pattern at every level: data flows down and requests bubble up. Each component is a function that takes streams of inputs and produces streams of outputs.

Staltz demonstrates the architecture in an alpha peer-to-peer social app, connecting a news feed and other components through streams. Ordinary React components can still be used inside it, while drivers handle native effects such as the Android status bar. He also suggests React Native's message-passing bridge could support similar interception and testing benefits.