Remove sandbox by making application more generic 🎉

examples/arc/src/main.rs

@@ -7,7 +7,7 @@ use iced::widget::canvas::{
 use iced::{Element, Length, Point, Rectangle, Renderer, Subscription, Theme};
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Arc - Iced", Arc::update, Arc::view)
+    iced::application("Arc - Iced", Arc::update, Arc::view)
         .subscription(Arc::subscription)
         .theme(|_| Theme::Dark)
         .antialiased()

examples/bezier_tool/src/main.rs

@@ -3,7 +3,7 @@ use iced::widget::{button, column, text};
 use iced::{Alignment, Element, Length};
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Bezier Tool - Iced", Example::update, Example::view)
+    iced::application("Bezier Tool - Iced", Example::update, Example::view)
         .antialiased()
         .run()
 }

examples/checkbox/src/main.rs

@@ -4,7 +4,7 @@ use iced::{Element, Font, Length};
 const ICON_FONT: Font = Font::with_name("icons");
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Checkbox - Iced", Example::update, Example::view)
+    iced::application("Checkbox - Iced", Example::update, Example::view)
         .font(include_bytes!("../fonts/icons.ttf").as_slice())
         .run()
 }

examples/clock/src/main.rs

@@ -8,7 +8,7 @@ use iced::{
 };
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Clock - Iced", Clock::update, Clock::view)
+    iced::application("Clock - Iced", Clock::update, Clock::view)
         .subscription(Clock::subscription)
         .theme(Clock::theme)
         .antialiased()

examples/color_palette/src/main.rs

@@ -13,7 +13,7 @@ use std::marker::PhantomData;
 use std::ops::RangeInclusive;
 
 pub fn main() -> iced::Result {
-    iced::sandbox(
+    iced::application(
         "Color Palette - Iced",
         ColorPalette::update,
         ColorPalette::view,

examples/custom_shader/src/main.rs

@@ -9,7 +9,11 @@ use iced::window;
 use iced::{Alignment, Color, Element, Length, Subscription};
 
 fn main() -> iced::Result {
-    iced::sandbox("Custom Shader - Iced", IcedCubes::update, IcedCubes::view)
+    iced::application(
+        "Custom Shader - Iced",
+        IcedCubes::update,
+        IcedCubes::view,
+    )
     .subscription(IcedCubes::subscription)
     .run()
 }

examples/download_progress/src/main.rs

@@ -4,7 +4,11 @@ use iced::widget::{button, column, container, progress_bar, text, Column};
 use iced::{Alignment, Element, Length, Subscription};
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Download Progress - Iced", Example::update, Example::view)
+    iced::application(
+        "Download Progress - Iced",
+        Example::update,
+        Example::view,
+    )
     .subscription(Example::subscription)
     .run()
 }

examples/geometry/src/main.rs

@@ -151,7 +151,7 @@ use iced::{Element, Length};
 use rainbow::rainbow;
 
 pub fn main() -> iced::Result {
-    iced::run("Custom 2D Geometry - Iced", |_, _| {}, view)
+    iced::run("Custom 2D Geometry - Iced", |_: &mut _, _| {}, view)
 }
 
 fn view(_state: &()) -> Element<'_, ()> {

examples/layout/src/main.rs

@@ -10,7 +10,7 @@ use iced::{
 };
 
 pub fn main() -> iced::Result {
-    iced::sandbox(Layout::title, Layout::update, Layout::view)
+    iced::application(Layout::title, Layout::update, Layout::view)
         .subscription(Layout::subscription)
         .theme(Layout::theme)
         .run()

examples/loading_spinners/src/main.rs

@@ -11,7 +11,7 @@ use circular::Circular;
 use linear::Linear;
 
 pub fn main() -> iced::Result {
-    iced::sandbox(
+    iced::application(
         "Loading Spinners - Iced",
         LoadingSpinners::update,
         LoadingSpinners::view,

examples/multitouch/src/main.rs

@@ -13,7 +13,7 @@ use std::collections::HashMap;
 pub fn main() -> iced::Result {
     tracing_subscriber::fmt::init();
 
-    iced::sandbox("Multitouch - Iced", Multitouch::update, Multitouch::view)
+    iced::application("Multitouch - Iced", Multitouch::update, Multitouch::view)
         .antialiased()
         .centered()
         .run()

examples/pane_grid/src/main.rs

@@ -7,7 +7,7 @@ use iced::widget::{
 use iced::{Color, Element, Length, Size, Subscription};
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Pane Grid - Iced", Example::update, Example::view)
+    iced::application("Pane Grid - Iced", Example::update, Example::view)
         .subscription(Example::subscription)
         .run()
 }

examples/qr_code/src/main.rs

@@ -4,7 +4,7 @@ use iced::widget::{
 use iced::{Alignment, Element, Length, Theme};
 
 pub fn main() -> iced::Result {
-    iced::sandbox(
+    iced::application(
         "QR Code Generator - Iced",
         QRGenerator::update,
         QRGenerator::view,

examples/sierpinski_triangle/src/main.rs

@@ -8,7 +8,7 @@ use rand::Rng;
 use std::fmt::Debug;
 
 fn main() -> iced::Result {
-    iced::sandbox(
+    iced::application(
         "Sierpinski Triangle - Iced",
         SierpinskiEmulator::update,
         SierpinskiEmulator::view,

examples/solar_system/src/main.rs

@@ -22,7 +22,7 @@ use std::time::Instant;
 pub fn main() -> iced::Result {
     tracing_subscriber::fmt::init();
 
-    iced::sandbox(
+    iced::application(
         "Solar System - Iced",
         SolarSystem::update,
         SolarSystem::view,

examples/stopwatch/src/main.rs

@@ -7,7 +7,7 @@ use iced::{Alignment, Element, Length, Subscription, Theme};
 use std::time::{Duration, Instant};
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Stopwatch - Iced", Stopwatch::update, Stopwatch::view)
+    iced::application("Stopwatch - Iced", Stopwatch::update, Stopwatch::view)
         .subscription(Stopwatch::subscription)
         .theme(Stopwatch::theme)
         .run()

examples/styling/src/main.rs

@@ -6,7 +6,7 @@ use iced::widget::{
 use iced::{Alignment, Element, Length, Theme};
 
 pub fn main() -> iced::Result {
-    iced::sandbox("Styling - Iced", Styling::update, Styling::view)
+    iced::application("Styling - Iced", Styling::update, Styling::view)
         .theme(Styling::theme)
         .run()
 }

examples/tour/src/main.rs

@@ -16,7 +16,7 @@ pub fn main() -> iced::Result {
     #[cfg(not(target_arch = "wasm32"))]
     tracing_subscriber::fmt::init();
 
-    iced::sandbox(Tour::title, Tour::update, Tour::view)
+    iced::application(Tour::title, Tour::update, Tour::view)
         .centered()
         .run()
 }

examples/url_handler/src/main.rs

@@ -3,7 +3,7 @@ use iced::widget::{container, text};
 use iced::{Element, Length, Subscription};
 
 pub fn main() -> iced::Result {
-    iced::sandbox("URL Handler - Iced", App::update, App::view)
+    iced::application("URL Handler - Iced", App::update, App::view)
         .subscription(App::subscription)
         .run()
 }

examples/vectorial_text/src/main.rs

@@ -6,7 +6,7 @@ use iced::widget::{
 use iced::{Element, Length, Point, Rectangle, Renderer, Theme, Vector};
 
 pub fn main() -> iced::Result {
-    iced::sandbox(
+    iced::application(
         "Vectorial Text - Iced",
         VectorialText::update,
         VectorialText::view,

runtime/src/command.rs

@@ -112,6 +112,12 @@ impl<T> Command<T> {
     }
 }
 
+impl<Message> From<()> for Command<Message> {
+    fn from(_value: ()) -> Self {
+        Self::none()
+    }
+}
+
 impl<T> fmt::Debug for Command<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         let Command(command) = self;

src/lib.rs

@@ -363,15 +363,15 @@ pub type Result = std::result::Result<(), Error>;
 /// ```
 pub fn run<State, Message>(
     title: impl program::Title<State> + 'static,
-    update: impl Fn(&mut State, Message) + 'static,
+    update: impl program::Update<State, Message> + 'static,
     view: impl for<'a> program::View<'a, State, Message> + 'static,
 ) -> Result
 where
     State: Default + 'static,
     Message: std::fmt::Debug + Send + 'static,
 {
-    sandbox(title, update, view).run()
+    application(title, update, view).run()
 }
 
 #[doc(inline)]
-pub use program::{application, sandbox};
+pub use program::application;

src/program.rs

@@ -15,7 +15,7 @@
 //! use iced::Theme;
 //!
 //! pub fn main() -> iced::Result {
-//!     iced::sandbox("A counter", update, view)
+//!     iced::application("A counter", update, view)
 //!         .theme(|_| Theme::Dark)
 //!         .centered()
 //!         .run()
@@ -46,14 +46,14 @@ use crate::{Command, Element, Font, Result, Settings, Subscription};
 
 use std::borrow::Cow;
 
-/// Creates the most basic kind of [`Program`] from some update and view logic.
+/// Creates an iced [`Program`] given its title, update, and view logic.
 ///
 /// # Example
 /// ```no_run
 /// use iced::widget::{button, column, text, Column};
 ///
 /// pub fn main() -> iced::Result {
-///     iced::sandbox("A counter", update, view).run()
+///     iced::application("A counter", update, view).run()
 /// }
 ///
 /// #[derive(Debug, Clone)]
@@ -74,78 +74,9 @@ use std::borrow::Cow;
 ///     ]
 /// }
 /// ```
-pub fn sandbox<State, Message>(
-    title: impl Title<State>,
-    update: impl Fn(&mut State, Message),
-    view: impl for<'a> self::View<'a, State, Message>,
-) -> Program<
-    impl Definition<State = State, Message = Message, Theme = crate::Theme>,
->
-where
-    State: Default + 'static,
-    Message: Send + std::fmt::Debug,
-{
-    use std::marker::PhantomData;
-
-    struct Sandbox<State, Message, Update, View> {
-        update: Update,
-        view: View,
-        _state: PhantomData<State>,
-        _message: PhantomData<Message>,
-    }
-
-    impl<State, Message, Update, View> Definition
-        for Sandbox<State, Message, Update, View>
-    where
-        State: Default + 'static,
-        Message: Send + std::fmt::Debug,
-        Update: Fn(&mut State, Message),
-        View: for<'a> self::View<'a, State, Message>,
-    {
-        type State = State;
-        type Message = Message;
-        type Theme = crate::Theme;
-        type Executor = iced_futures::backend::null::Executor;
-
-        fn build(&self) -> (Self::State, Command<Self::Message>) {
-            (State::default(), Command::none())
-        }
-
-        fn update(
-            &self,
-            state: &mut Self::State,
-            message: Self::Message,
-        ) -> Command<Self::Message> {
-            (self.update)(state, message);
-
-            Command::none()
-        }
-
-        fn view<'a>(
-            &self,
-            state: &'a Self::State,
-        ) -> Element<'a, Self::Message, Self::Theme> {
-            self.view.view(state).into()
-        }
-    }
-
-    Program {
-        raw: Sandbox {
-            update,
-            view,
-            _state: PhantomData,
-            _message: PhantomData,
-        },
-        settings: Settings::default(),
-    }
-    .title(title)
-}
-
-/// Creates a [`Program`] that can leverage the [`Command`] API for
-/// concurrent operations.
 pub fn application<State, Message>(
     title: impl Title<State>,
-    update: impl Fn(&mut State, Message) -> Command<Message>,
+    update: impl Update<State, Message>,
     view: impl for<'a> self::View<'a, State, Message>,
 ) -> Program<
     impl Definition<State = State, Message = Message, Theme = crate::Theme>,
@@ -168,7 +99,7 @@ where
     where
         State: Default,
         Message: Send + std::fmt::Debug,
-        Update: Fn(&mut State, Message) -> Command<Message>,
+        Update: self::Update<State, Message>,
         View: for<'a> self::View<'a, State, Message>,
     {
         type State = State;
@@ -185,7 +116,7 @@ where
             state: &mut Self::State,
             message: Self::Message,
         ) -> Command<Self::Message> {
-            (self.update)(state, message)
+            self.update.update(state, message).into()
         }
 
         fn view<'a>(
@@ -704,18 +635,44 @@ where
     }
 }
 
+/// The update logic of some [`Program`].
+///
+/// This trait allows [`application`] to take any closure that
+/// returns any `Into<Command<Message>>`.
+///
+/// [`application`]: self::application()
+pub trait Update<State, Message> {
+    /// Processes the message and updates the state of the [`Program`].
+    fn update(
+        &self,
+        state: &mut State,
+        message: Message,
+    ) -> impl Into<Command<Message>>;
+}
+
+impl<T, State, Message, C> Update<State, Message> for T
+where
+    T: Fn(&mut State, Message) -> C,
+    C: Into<Command<Message>>,
+{
+    fn update(
+        &self,
+        state: &mut State,
+        message: Message,
+    ) -> impl Into<Command<Message>> {
+        self(state, message)
+    }
+}
+
 /// The view logic of some [`Program`].
 ///
-/// This trait allows [`sandbox`] and [`application`] to
-/// take any closure that returns any `Into<Element<'_, Message>>`.
+/// This trait allows [`application`] to take any closure that
+/// returns any `Into<Element<'_, Message>>`.
 ///
 /// [`application`]: self::application()
 pub trait View<'a, State, Message> {
-    /// The widget returned by the view logic.
-    type Widget: Into<Element<'a, Message>>;
-
     /// Produces the widget of the [`Program`].
-    fn view(&self, state: &'a State) -> Self::Widget;
+    fn view(&self, state: &'a State) -> impl Into<Element<'a, Message>>;
 }
 
 impl<'a, T, State, Message, Widget> View<'a, State, Message> for T
@@ -724,9 +681,7 @@ where
     State: 'static,
     Widget: Into<Element<'a, Message>>,
 {
-    type Widget = Widget;
-
-    fn view(&self, state: &'a State) -> Self::Widget {
+    fn view(&self, state: &'a State) -> impl Into<Element<'a, Message>> {
         self(state)
     }
 }