1 unstable release
0.1.0 | Sep 4, 2024 |
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#774 in Rust patterns
42 downloads per month
Used in tgpt
35KB
765 lines
The Composable Architecture
Note: that is currently a prototype developed for my own learning Rust sake and couple of terminal-UI apps.
The Composable Architecture (TCA, for short) is a library for building applications in a consistent and understandable way, with composition, testing, and ergonomics in mind.
This library is heavily inspired by TCA implementation for Swift language.
Usage
There are 3 main components. First, define your State
, Action
and Feature
.
#[derive(Clone, Eq)]
struct State {
counter: i32,
}
#[derive(Debug)]
enum Action {
UpdateCounter(i32),
}
struct Feature {}
Then, we need to implement Reducer
trait for Feature
:
impl tca::Reducer<State, Action> for Feature {
fn reduce(state: &mut State, action: Action) -> Effect<Action> {
match action {
Action::UpdateCounter(counter) => {
state.counter = counter;
Effect::none()
}
}
}
}
Now you can create new Store
to use in you main event loop. Let's use ratatui crate as our UI library.
#[tokio::main]
fn main() -> anyhow::Result<()> {
let terminal = /* Creating and preparing terminal here */;
// Instantiate root store.
let store = tca::Store::new::<Feature>(State::default());
// Stream of redraw requests. Called each time `State` is changed by `Reducer`.
let mut redraw_events = store.observe();
// Stream of terminal events (e.g. key presses).
let mut terminal_events = crossterm::event::EventStream::new();
// Our main event loop.
loop {
let crossterm_event = terminal_events.next().fuse();
let redraw_event = redraw_events.recv().fuse();
tokio::select! {
maybe_redraw = redraw_event => {
match maybe_redraw {
Ok(()) => {
terminal.draw(|f| ui(f, &state))?;
},
Err(tokio::sync::broadcast::error::RecvError::Closed) => {
break;
},
Err(tokio::sync::broadcast::error::RecvError::Lagged(_)) => {
continue;
}
}
}
maybe_event = crossterm_event => {
match maybe_event {
Some(Ok(evt)) => store.send(Action::Event(evt)),
Some(Err(err)) => return Err(err.into()),
None => continue,
}
}
}
}
Ok(())
}
Dependencies
~3.5–9.5MB
~94K SLoC