Actuate

Examples

A high-performance and borrow-checker friendly framework for declarative programming in Rust. This crate provides a generic library that lets you define reactive components (also known as composables).

Features

• Declarative and reactive scenes for Bevy
• Efficient and borrow-checker friendly state management: Manage state with components and hooks, all using zero-cost smart pointers
• Generic core for custom backends

// Counter UI example.

use actuate::prelude::*;
use bevy::prelude::*;

// Counter composable.
#[derive(Data)]
struct Counter {
    start: i32,
}

impl Compose for Counter {
    fn compose(cx: Scope<Self>) -> impl Compose {
        let count = use_mut(&cx, || cx.me().start);

        spawn(Node {
            flex_direction: FlexDirection::Column,
            ..default()
        })
        .content((
            spawn(Text::new(format!("High five count: {}", count))),
            spawn(Text::new("Up high"))
                .observe(move |_: Trigger<Pointer<Click>>| SignalMut::update(count, |x| *x += 1)),
            spawn(Text::new("Down low"))
                .observe(move |_: Trigger<Pointer<Click>>| SignalMut::update(count, |x| *x -= 1)),
            if *count == 0 {
                Some(spawn(Text::new("Gimme five!")))
            } else {
                None
            },
        ))
    }
}

fn setup(mut commands: Commands) {
    commands.spawn(Camera2d::default());

    // Spawn a composition with a `Counter`, adding it to the Actuate runtime.
    commands.spawn((Node::default(), Composition::new(Counter { start: 0 })));
}

fn main() {
    App::new()
        .add_plugins((DefaultPlugins, ActuatePlugin))
        .add_systems(Startup, setup)
        .run();
}

Borrowing

Composables can borrow from their ancestors, as well as state.

use actuate::prelude::*;

#[derive(Data)]
struct User<'a> {
    // `actuate::Cow` allows for either a borrowed or owned value.
    name: Cow<'a, String>,
}

impl Compose for User<'_> {
    fn compose(cx: Scope<Self>) -> impl Compose {
        spawn(Text::new(cx.me().name.to_string()))
    }
}

#[derive(Data)]
struct App {
    name: String
}

impl Compose for App {
    fn compose(cx: Scope<Self>) -> impl Compose {
        // Get a mapped reference to the app's `name` field.
        let name = Signal::map(cx.me(), |me| &me.name).into();

        User { name }
    }
}

Installation

To add this crate to your project:

cargo add actuate --features full

Inspiration

This crate is inspired by Xilem and uses a similar approach to type-safe reactivity. The main difference with this crate is the concept of scopes, components store their state in their own scope and updates to that scope re-render the component.

State management is inspired by React and Dioxus.

Previous implementations were in Concoct but were never very compatible with lifetimes.