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Putting it all together, we have the function:

/// Application.
pub mod app;
/// Terminal events handler.
pub mod event;
/// Widget renderer.
pub mod ui;
/// Terminal user interface.
pub mod tui;
/// Application updater.
pub mod update;
use app::App;
use color_eyre::Result;
use event::{Event, EventHandler};
use ratatui::{backend::CrosstermBackend, Terminal};
use tui::Tui;
use update::update;
fn main() -> Result<()> {
// Create an application.
let mut app = App::new();
// Initialize the terminal user interface.
let backend = CrosstermBackend::new(std::io::stderr());
let terminal = Terminal::new(backend)?;
let events = EventHandler::new(250);
let mut tui = Tui::new(terminal, events);
// Start the main loop.
while !app.should_quit {
// Render the user interface.
tui.draw(&mut app)?;
// Handle events.
match {
Event::Tick => {}
Event::Key(key_event) => update(&mut app, key_event),
Event::Mouse(_) => {}
Event::Resize(_, _) => {}
// Exit the user interface.

Because we call in a loop, it blocks until there’s an event generated. If there’s a key press, the state updates and the UI is refreshed. If there’s no key press, a Tick event is generated every 250 milliseconds, which causes the UI to be refreshed.

This is what it looks like in practice to:

  • Run the TUI
  • Wait 2.5 seconds
  • Press j 5 times
  • Wait 2.5 seconds
  • Press k 5 times
  • Wait 2.5 seconds
  • Press q

Counter app demo

You can find the full source code for this multiple files tutorial here: