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tui-dispatch

Counter Example

The simplest possible tui-dispatch app - a counter that you can increment and decrement.

Run it

Terminal window
cargo run -p counter-example

Keys

  • k / Up - increment
  • j / Down - decrement
  • q / Esc - quit

What it demonstrates

This ~120 line example shows the core pattern without any extensions:

  1. State - A struct holding what the app knows
  2. Actions - An enum describing what can happen
  3. Reducer - A function that updates state based on actions
  4. Store - Container that holds state and applies reducer
  5. Main loop - Synchronous event polling, action dispatch, conditional render

No async runtime, no EventBus, no debug layer — just the essentials.

Code walkthrough

State

#[derive(Default)]
struct AppState {
    count: i32,
}

Actions

#[derive(Clone, Debug, Action)]
enum Action {
    Increment,
    Decrement,
    Quit,
}

Reducer

fn reducer(state: &mut AppState, action: Action) -> bool {
    match action {
        Action::Increment => {
            state.count += 1;
            true  // state changed, need re-render
        }
        Action::Decrement => {
            state.count -= 1;
            true
        }
        Action::Quit => false,  // handled in main loop
    }
}

The reducer returns bool - true means state changed and UI should re-render.

Store + Main Loop

let mut store = Store::new(AppState::default(), reducer);


loop {
    // Render
    terminal.draw(|frame| {
        // ... render UI using store.state() ...
    })?;


    // Handle input
    if let Event::Key(key) = event::read()? {
        let action = match key.code {
            KeyCode::Char('k') | KeyCode::Up => Action::Increment,
            KeyCode::Char('j') | KeyCode::Down => Action::Decrement,
            KeyCode::Char('q') | KeyCode::Esc => Action::Quit,
            _ => continue,
        };


        if !store.dispatch(action) {
            break;
        }
    }
}

The loop renders, waits for a key event, maps it to an action, and dispatches. When dispatch returns false (the Quit arm), the loop exits.

Next steps