🍵 chai-tea

a minimal Elm-style architecture for egui / eframe apps

Status: early-stage but functional — now with async / background task support. API may change rapidly as development continues.

chai-tea lets you write GUI apps in the same clean loop you’d use in The Elm Architecture (TEA):

use eframe::egui;

#[derive(Default)]
struct Model { counter: i32 }
enum Msg { Inc, Dec }

fn init() -> Model { Model { counter: 0 } }

fn update(m: Model, msg: Msg) -> Model {
    match msg {
        Msg::Inc => Model { counter: m.counter + 1, ..m },
        Msg::Dec => Model { counter: m.counter - 1, ..m },
    }
}

fn view(ctx: &egui::Context, m: &Model, tx: &mut Vec<Msg>) {
    egui::CentralPanel::default().show(ctx, |ui| {
        if ui.button("+").clicked() { tx.push(Msg::Inc); }
        if ui.button("–").clicked() { tx.push(Msg::Dec); }
        ui.label(m.counter.to_string());
    });
}

fn main() -> eframe::Result<()> {
    chai_tea::brew(init, update, view)
}

add eframe to your dependencies, run it and you’ve got a fully working counter app.

cargo run --example counter

🧩 example: async counters

A minimal demonstration of concurrent background workers, shared atomic state, and repaint-on-message behavior is included under

cargo run --example multicounter

Each counter runs in its own thread and reports back through ChaiSender, automatically triggering redraws.

✨ features

• 🍃 Pure Elm-style loop — deterministic, functional, and testable
• 🧵 Async commands via brew_async, SyncState, and ChaiSender
  • spawn background threads or async tasks
  • send messages back safely
  • UI automatically repaints on message arrival
• 🌐 Native + (soon) WASM support
• 🪶 Tiny, dependency-light core
• ☕ Ergonomic aliases — brew = run, brew_async = run_async

🫖 possible roadmap

• async / background command support
• fixed-timestep threaded simulation variant
• wasm runner (chai_tea::run_web)
• macro sugar: #[chai_app]
• theme system (chai-latte someday?)
• time travel debugger?