Impl `View` directly on text, and refactor action return types.

Cargo.lock

@@ -1215,6 +1215,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "28999cda5ef6916ffd33fb4a7b87e1de633c47c0dc6d97905fee1cdaa142b94d"
 dependencies = [
  "gloo-events",
+ "gloo-utils",
 ]
 
 [[package]]
@@ -1227,6 +1228,19 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "gloo-utils"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "037fcb07216cb3a30f7292bd0176b050b7b9a052ba830ef7d5d65f6dc64ba58e"
+dependencies = [
+ "js-sys",
+ "serde",
+ "serde_json",
+ "wasm-bindgen",
+ "web-sys",
+]
+
 [[package]]
 name = "glow"
 version = "0.12.2"
@@ -1498,6 +1512,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "453ad9f582a441959e5f0d088b02ce04cfe8d51a8eaf077f12ac6d3e94164ca6"
+
 [[package]]
 name = "js-sys"
 version = "0.3.64"
@@ -2244,6 +2264,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "ryu"
+version = "1.0.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f91339c0467de62360649f8d3e185ca8de4224ff281f66000de5eb2a77a79041"
+
 [[package]]
 name = "scopeguard"
 version = "1.1.0"
@@ -2276,6 +2302,17 @@ dependencies = [
  "syn 2.0.18",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46266871c240a00b8f503b877622fe33430b3c7d963bdc0f2adc511e54a1eae3"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
 [[package]]
 name = "serde_repr"
 version = "0.1.12"

crates/xilem_html/Cargo.toml

@@ -6,68 +6,7 @@ edition = "2021"
 
 [features]
 default = ["typed"]
-typed = [
+typed = ['web-sys/FocusEvent', 'web-sys/HtmlAnchorElement', 'web-sys/HtmlAreaElement', 'web-sys/HtmlAudioElement', 'web-sys/HtmlBrElement', 'web-sys/HtmlButtonElement', 'web-sys/HtmlCanvasElement', 'web-sys/HtmlDataElement', 'web-sys/HtmlDataListElement', 'web-sys/HtmlDetailsElement', 'web-sys/HtmlDialogElement', 'web-sys/HtmlDivElement', 'web-sys/HtmlDListElement', 'web-sys/HtmlEmbedElement', 'web-sys/HtmlFieldSetElement', 'web-sys/HtmlFormElement', 'web-sys/HtmlHeadingElement', 'web-sys/HtmlHrElement', 'web-sys/HtmlIFrameElement', 'web-sys/HtmlImageElement', 'web-sys/HtmlInputElement', 'web-sys/HtmlLabelElement', 'web-sys/HtmlLegendElement', 'web-sys/HtmlLiElement', 'web-sys/HtmlMapElement', 'web-sys/HtmlMenuElement', 'web-sys/HtmlMeterElement', 'web-sys/HtmlModElement', 'web-sys/HtmlObjectElement', 'web-sys/HtmlOListElement', 'web-sys/HtmlOptGroupElement', 'web-sys/HtmlOptionElement', 'web-sys/HtmlOutputElement', 'web-sys/HtmlParagraphElement', 'web-sys/HtmlPictureElement', 'web-sys/HtmlPreElement', 'web-sys/HtmlProgressElement', 'web-sys/HtmlQuoteElement', 'web-sys/HtmlScriptElement', 'web-sys/HtmlSelectElement', 'web-sys/HtmlSlotElement', 'web-sys/HtmlSourceElement', 'web-sys/HtmlSpanElement', 'web-sys/HtmlTableElement', 'web-sys/HtmlTableCellElement', 'web-sys/HtmlTableColElement', 'web-sys/HtmlTableCaptionElement', 'web-sys/HtmlTableRowElement', 'web-sys/HtmlTableSectionElement', 'web-sys/HtmlTemplateElement', 'web-sys/HtmlTextAreaElement', 'web-sys/HtmlTimeElement', 'web-sys/HtmlTrackElement', 'web-sys/HtmlUListElement', 'web-sys/HtmlVideoElement', 'web-sys/InputEvent', 'web-sys/KeyboardEvent', 'web-sys/MouseEvent', 'web-sys/PointerEvent', 'web-sys/WheelEvent']
-    'web-sys/FocusEvent',
-    'web-sys/HtmlAnchorElement',
-    'web-sys/HtmlAreaElement',
-    'web-sys/HtmlAudioElement',
-    'web-sys/HtmlBrElement',
-    'web-sys/HtmlButtonElement',
-    'web-sys/HtmlCanvasElement',
-    'web-sys/HtmlDataElement',
-    'web-sys/HtmlDataListElement',
-    'web-sys/HtmlDetailsElement',
-    'web-sys/HtmlDialogElement',
-    'web-sys/HtmlDivElement',
-    'web-sys/HtmlDListElement',
-    'web-sys/HtmlEmbedElement',
-    'web-sys/HtmlFieldSetElement',
-    'web-sys/HtmlFormElement',
-    'web-sys/HtmlHeadingElement',
-    'web-sys/HtmlHrElement',
-    'web-sys/HtmlIFrameElement',
-    'web-sys/HtmlImageElement',
-    'web-sys/HtmlInputElement',
-    'web-sys/HtmlLabelElement',
-    'web-sys/HtmlLegendElement',
-    'web-sys/HtmlLiElement',
-    'web-sys/HtmlMapElement',
-    'web-sys/HtmlMenuElement',
-    'web-sys/HtmlMeterElement',
-    'web-sys/HtmlModElement',
-    'web-sys/HtmlObjectElement',
-    'web-sys/HtmlOListElement',
-    'web-sys/HtmlOptGroupElement',
-    'web-sys/HtmlOptionElement',
-    'web-sys/HtmlOutputElement',
-    'web-sys/HtmlParagraphElement',
-    'web-sys/HtmlPictureElement',
-    'web-sys/HtmlPreElement',
-    'web-sys/HtmlProgressElement',
-    'web-sys/HtmlQuoteElement',
-    'web-sys/HtmlScriptElement',
-    'web-sys/HtmlSelectElement',
-    'web-sys/HtmlSlotElement',
-    'web-sys/HtmlSourceElement',
-    'web-sys/HtmlSpanElement',
-    'web-sys/HtmlTableElement',
-    'web-sys/HtmlTableCellElement',
-    'web-sys/HtmlTableColElement',
-    'web-sys/HtmlTableCaptionElement',
-    'web-sys/HtmlTableRowElement',
-    'web-sys/HtmlTableSectionElement',
-    'web-sys/HtmlTemplateElement',
-    'web-sys/HtmlTextAreaElement',
-    'web-sys/HtmlTimeElement',
-    'web-sys/HtmlTrackElement',
-    'web-sys/HtmlUListElement',
-    'web-sys/HtmlVideoElement',
-    'web-sys/InputEvent',
-    'web-sys/KeyboardEvent',
-    'web-sys/MouseEvent',
-    'web-sys/PointerEvent',
-    'web-sys/WheelEvent',
-]
 
 [dependencies]
 bitflags = "1.3.2"
@@ -75,7 +14,7 @@ wasm-bindgen = "0.2.87"
 kurbo = "0.9.1"
 xilem_core = { path = "../xilem_core" }
 log = "0.4.19"
-gloo = { version = "0.8.1", default-features = false, features = ["events"] }
+gloo = { version = "0.8.1", default-features = false, features = ["events", "utils"] }
 
 [dependencies.web-sys]
 version = "0.3.4"

crates/xilem_html/src/event/events.rs

@@ -10,19 +10,49 @@ macro_rules! events {
 
 macro_rules! event {
     ($ty_name:ident, $builder_name:ident, $name:literal, $web_sys_ty:ty) => {
-        pub struct $ty_name<V, F>(crate::OnEvent<$web_sys_ty, V, F>);
+        pub struct $ty_name<T, A, V, F, OA>
-
-        pub fn $builder_name<V, F>(child: V, callback: F) -> $ty_name<V, F> {
-            $ty_name(crate::on_event($name, child, callback))
-        }
-
-        impl<V, F> crate::view::ViewMarker for $ty_name<V, F> {}
-
-        impl<T, A, V, F> crate::view::View<T, A> for $ty_name<V, F>
         where
             V: crate::view::View<T, A>,
-            F: Fn(&mut T, &$crate::Event<$web_sys_ty, V::Element>) -> $crate::MessageResult<A>,
+            F: Fn(&mut T, &$crate::Event<$web_sys_ty, V::Element>) -> OA,
             V::Element: 'static,
+            OA: $crate::event::OptionalAction<A>,
+        {
+            inner: crate::OnEvent<$web_sys_ty, V, F>,
+            data: std::marker::PhantomData<T>,
+            action: std::marker::PhantomData<A>,
+            optional_action: std::marker::PhantomData<OA>,
+        }
+
+        pub fn $builder_name<T, A, V, F, OA>(child: V, callback: F) -> $ty_name<T, A, V, F, OA>
+        where
+            V: crate::view::View<T, A>,
+            F: Fn(&mut T, &$crate::Event<$web_sys_ty, V::Element>) -> OA,
+            V::Element: 'static,
+            OA: $crate::event::OptionalAction<A>,
+        {
+            $ty_name {
+                inner: crate::on_event($name, child, callback),
+                data: std::marker::PhantomData,
+                action: std::marker::PhantomData,
+                optional_action: std::marker::PhantomData,
+            }
+        }
+
+        impl<T, A, V, F, OA> crate::view::ViewMarker for $ty_name<T, A, V, F, OA>
+        where
+            V: crate::view::View<T, A>,
+            F: Fn(&mut T, &$crate::Event<$web_sys_ty, V::Element>) -> OA,
+            V::Element: 'static,
+            OA: $crate::event::OptionalAction<A>,
+        {
+        }
+
+        impl<T, A, V, F, OA> crate::view::View<T, A> for $ty_name<T, A, V, F, OA>
+        where
+            V: crate::view::View<T, A>,
+            F: Fn(&mut T, &$crate::Event<$web_sys_ty, V::Element>) -> OA,
+            V::Element: 'static,
+            OA: $crate::event::OptionalAction<A>,
         {
             type State = crate::event::OnEventState<V::State>;
             type Element = V::Element;
@@ -31,7 +61,7 @@ macro_rules! event {
                 &self,
                 cx: &mut crate::context::Cx,
             ) -> (xilem_core::Id, Self::State, Self::Element) {
-                self.0.build(cx)
+                self.inner.build(cx)
             }
 
             fn rebuild(
@@ -42,7 +72,7 @@ macro_rules! event {
                 state: &mut Self::State,
                 element: &mut Self::Element,
             ) -> crate::ChangeFlags {
-                self.0.rebuild(cx, &prev.0, id, state, element)
+                self.inner.rebuild(cx, &prev.inner, id, state, element)
             }
 
             fn message(
@@ -52,7 +82,7 @@ macro_rules! event {
                 message: Box<dyn std::any::Any>,
                 app_state: &mut T,
             ) -> xilem_core::MessageResult<A> {
-                self.0.message(id_path, state, message, app_state)
+                self.inner.message(id_path, state, message, app_state)
             }
         }
     };

crates/xilem_html/src/event/mod.rs

@@ -37,12 +37,13 @@ impl<E, V, F> OnEvent<E, V, F> {
 
 impl<E, V, F> ViewMarker for OnEvent<E, V, F> {}
 
-impl<T, A, E, F, V> View<T, A> for OnEvent<E, V, F>
+impl<T, A, E, F, V, OA> View<T, A> for OnEvent<E, V, F>
 where
-    F: Fn(&mut T, &Event<E, V::Element>) -> MessageResult<A>,
+    F: Fn(&mut T, &Event<E, V::Element>) -> OA,
     V: View<T, A>,
     E: JsCast + 'static,
     V::Element: 'static,
+    OA: OptionalAction<A>,
 {
     type State = OnEventState<V::State>;
 
@@ -90,7 +91,10 @@ where
         app_state: &mut T,
     ) -> MessageResult<A> {
         if let Some(msg) = message.downcast_ref::<EventMsg<Event<E, V::Element>>>() {
-            (self.callback)(app_state, &msg.event)
+            match (self.callback)(app_state, &msg.event).action() {
+                Some(a) => MessageResult::Action(a),
+                None => MessageResult::Nop,
+            }
         } else {
             self.child
                 .message(id_path, &mut state.child_state, message, app_state)
@@ -143,3 +147,39 @@ impl<Evt, El> Deref for Event<Evt, El> {
         &self.raw
     }
 }
+
+/// Implement this trait for types you want to use as actions.
+///
+/// The trait exists because otherwise we couldn't provide versions
+/// of listeners that take `()`, `A` and `Option<A>`.
+pub trait Action {}
+
+/// Trait that allows callbacks to be polymorphic on return type
+/// (`Action`, `Option<Action>` or `()`)
+pub trait OptionalAction<A>: sealed::Sealed {
+    fn action(self) -> Option<A>;
+}
+mod sealed {
+    pub trait Sealed {}
+}
+
+impl sealed::Sealed for () {}
+impl<A> OptionalAction<A> for () {
+    fn action(self) -> Option<A> {
+        None
+    }
+}
+
+impl<A: Action> sealed::Sealed for A {}
+impl<A: Action> OptionalAction<A> for A {
+    fn action(self) -> Option<A> {
+        Some(self)
+    }
+}
+
+impl<A: Action> sealed::Sealed for Option<A> {}
+impl<A: Action> OptionalAction<A> for Option<A> {
+    fn action(self) -> Option<A> {
+        self
+    }
+}

crates/xilem_html/src/lib.rs

@@ -14,7 +14,6 @@ mod context;
 mod event;
 //mod div;
 mod element;
-mod text;
 mod view;
 #[cfg(feature = "typed")]
 mod view_ext;
@@ -29,8 +28,7 @@ pub use element::elements;
 pub use element::{element, Element, ElementState};
 #[cfg(feature = "typed")]
 pub use event::events;
-pub use event::{on_event, Event, OnEvent, OnEventState};
+pub use event::{on_event, Action, Event, OnEvent, OnEventState, OptionalAction};
-pub use text::{text, Text};
 pub use view::{Adapt, AdaptThunk, Pod, View, ViewMarker, ViewSequence};
 #[cfg(feature = "typed")]
 pub use view_ext::ViewExt;

crates/xilem_html/src/text.rs

@@ -1,61 +0,0 @@
-use std::borrow::Cow;
-use wasm_bindgen::JsCast;
-
-use xilem_core::{Id, MessageResult};
-
-use crate::{
-    context::{ChangeFlags, Cx},
-    view::{View, ViewMarker},
-};
-
-pub struct Text {
-    text: Cow<'static, str>,
-}
-
-/// Create a text node
-pub fn text(text: impl Into<Cow<'static, str>>) -> Text {
-    Text { text: text.into() }
-}
-
-impl ViewMarker for Text {}
-
-impl<T, A> View<T, A> for Text {
-    type State = ();
-    type Element = web_sys::Text;
-
-    fn build(&self, _cx: &mut Cx) -> (Id, Self::State, Self::Element) {
-        let el = new_text(&self.text);
-        let id = Id::next();
-        (id, (), el.unchecked_into())
-    }
-
-    fn rebuild(
-        &self,
-        _cx: &mut Cx,
-        prev: &Self,
-        _id: &mut Id,
-        _state: &mut Self::State,
-        element: &mut Self::Element,
-    ) -> ChangeFlags {
-        let mut is_changed = ChangeFlags::empty();
-        if prev.text != self.text {
-            element.set_data(&self.text);
-            is_changed |= ChangeFlags::OTHER_CHANGE;
-        }
-        is_changed
-    }
-
-    fn message(
-        &self,
-        _id_path: &[Id],
-        _state: &mut Self::State,
-        _message: Box<dyn std::any::Any>,
-        _app_state: &mut T,
-    ) -> MessageResult<A> {
-        MessageResult::Nop
-    }
-}
-
-fn new_text(text: &str) -> web_sys::Text {
-    web_sys::Text::new_with_data(text).unwrap()
-}

crates/xilem_html/src/view.rs

@@ -4,7 +4,9 @@
 //! Integration with xilem_core. This instantiates the View and related
 //! traits for DOM node generation.
 
-use std::{any::Any, ops::Deref};
+use std::{any::Any, borrow::Cow, ops::Deref};
+
+use xilem_core::{Id, MessageResult};
 
 use crate::{context::Cx, ChangeFlags};
 
@@ -98,3 +100,121 @@ impl Pod {
 xilem_core::generate_view_trait! {View, DomNode, Cx, ChangeFlags;}
 xilem_core::generate_viewsequence_trait! {ViewSequence, View, ViewMarker, DomNode, Cx, ChangeFlags, Pod;}
 xilem_core::generate_anyview_trait! {View, Cx, ChangeFlags, AnyNode}
+
+impl ViewMarker for &'static str {}
+impl<T, A> View<T, A> for &'static str {
+    type State = ();
+    type Element = web_sys::Text;
+
+    fn build(&self, _cx: &mut Cx) -> (Id, Self::State, Self::Element) {
+        let el = new_text(self);
+        let id = Id::next();
+        (id, (), el.into())
+    }
+
+    fn rebuild(
+        &self,
+        _cx: &mut Cx,
+        prev: &Self,
+        _id: &mut Id,
+        _state: &mut Self::State,
+        element: &mut Self::Element,
+    ) -> ChangeFlags {
+        let mut is_changed = ChangeFlags::empty();
+        if prev != self {
+            element.set_data(self);
+            is_changed |= ChangeFlags::OTHER_CHANGE;
+        }
+        is_changed
+    }
+
+    fn message(
+        &self,
+        _id_path: &[Id],
+        _state: &mut Self::State,
+        _message: Box<dyn std::any::Any>,
+        _app_state: &mut T,
+    ) -> MessageResult<A> {
+        MessageResult::Nop
+    }
+}
+
+impl ViewMarker for String {}
+impl<T, A> View<T, A> for String {
+    type State = ();
+    type Element = web_sys::Text;
+
+    fn build(&self, _cx: &mut Cx) -> (Id, Self::State, Self::Element) {
+        let el = new_text(self);
+        let id = Id::next();
+        (id, (), el.into())
+    }
+
+    fn rebuild(
+        &self,
+        _cx: &mut Cx,
+        prev: &Self,
+        _id: &mut Id,
+        _state: &mut Self::State,
+        element: &mut Self::Element,
+    ) -> ChangeFlags {
+        let mut is_changed = ChangeFlags::empty();
+        if prev != self {
+            element.set_data(self);
+            is_changed |= ChangeFlags::OTHER_CHANGE;
+        }
+        is_changed
+    }
+
+    fn message(
+        &self,
+        _id_path: &[Id],
+        _state: &mut Self::State,
+        _message: Box<dyn std::any::Any>,
+        _app_state: &mut T,
+    ) -> MessageResult<A> {
+        MessageResult::Nop
+    }
+}
+
+impl ViewMarker for Cow<'static, str> {}
+impl<T, A> View<T, A> for Cow<'static, str> {
+    type State = ();
+    type Element = web_sys::Text;
+
+    fn build(&self, _cx: &mut Cx) -> (Id, Self::State, Self::Element) {
+        let el = new_text(self);
+        let id = Id::next();
+        (id, (), el.into())
+    }
+
+    fn rebuild(
+        &self,
+        _cx: &mut Cx,
+        prev: &Self,
+        _id: &mut Id,
+        _state: &mut Self::State,
+        element: &mut Self::Element,
+    ) -> ChangeFlags {
+        let mut is_changed = ChangeFlags::empty();
+        if prev != self {
+            element.set_data(self);
+            is_changed |= ChangeFlags::OTHER_CHANGE;
+        }
+        is_changed
+    }
+
+    fn message(
+        &self,
+        _id_path: &[Id],
+        _state: &mut Self::State,
+        _message: Box<dyn std::any::Any>,
+        _app_state: &mut T,
+    ) -> MessageResult<A> {
+        MessageResult::Nop
+    }
+}
+
+fn new_text(text: &str) -> web_sys::Text {
+    web_sys::Text::new_with_data(text).unwrap()
+}

crates/xilem_html/src/view_ext.rs

@@ -3,61 +3,77 @@
 
 use std::borrow::Cow;
 
-use xilem_core::MessageResult;
+use crate::{class::Class, event::OptionalAction, events as e, view::View, Event};
-
-use crate::{class::Class, events as e, view::View, Event};
 
 pub trait ViewExt<T, A>: View<T, A> + Sized {
-    fn on_click<F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> MessageResult<A>>(
+    fn on_click<
-        self,
+        OA: OptionalAction<A>,
-        f: F,
+        F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> OA,
-    ) -> e::OnClick<Self, F>;
-    fn on_dblclick<F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> MessageResult<A>>(
-        self,
-        f: F,
-    ) -> e::OnDblClick<Self, F>;
-    fn on_input<F: Fn(&mut T, &Event<web_sys::InputEvent, Self::Element>) -> MessageResult<A>>(
-        self,
-        f: F,
-    ) -> e::OnInput<Self, F>;
-    fn on_keydown<
-        F: Fn(&mut T, &Event<web_sys::KeyboardEvent, Self::Element>) -> MessageResult<A>,
     >(
         self,
         f: F,
-    ) -> e::OnKeyDown<Self, F>;
+    ) -> e::OnClick<T, A, Self, F, OA>;
+    fn on_dblclick<
+        OA: OptionalAction<A>,
+        F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> OA,
+    >(
+        self,
+        f: F,
+    ) -> e::OnDblClick<T, A, Self, F, OA>;
+    fn on_input<
+        OA: OptionalAction<A>,
+        F: Fn(&mut T, &Event<web_sys::InputEvent, Self::Element>) -> OA,
+    >(
+        self,
+        f: F,
+    ) -> e::OnInput<T, A, Self, F, OA>;
+    fn on_keydown<
+        OA: OptionalAction<A>,
+        F: Fn(&mut T, &Event<web_sys::KeyboardEvent, Self::Element>) -> OA,
+    >(
+        self,
+        f: F,
+    ) -> e::OnKeyDown<T, A, Self, F, OA>;
     fn class(self, class: impl Into<Cow<'static, str>>) -> Class<Self> {
         crate::class::class(self, class)
     }
 }
 
 impl<T, A, V: View<T, A>> ViewExt<T, A> for V {
-    fn on_click<F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> MessageResult<A>>(
+    fn on_click<
+        OA: OptionalAction<A>,
+        F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> OA,
+    >(
         self,
         f: F,
-    ) -> e::OnClick<Self, F> {
+    ) -> e::OnClick<T, A, Self, F, OA> {
         e::on_click(self, f)
     }
     fn on_dblclick<
-        F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> MessageResult<A>,
+        OA: OptionalAction<A>,
+        F: Fn(&mut T, &Event<web_sys::MouseEvent, Self::Element>) -> OA,
     >(
         self,
         f: F,
-    ) -> e::OnDblClick<Self, F> {
+    ) -> e::OnDblClick<T, A, Self, F, OA> {
         e::on_dblclick(self, f)
     }
-    fn on_input<F: Fn(&mut T, &Event<web_sys::InputEvent, Self::Element>) -> MessageResult<A>>(
+    fn on_input<
+        OA: OptionalAction<A>,
+        F: Fn(&mut T, &Event<web_sys::InputEvent, Self::Element>) -> OA,
+    >(
         self,
         f: F,
-    ) -> e::OnInput<Self, F> {
+    ) -> e::OnInput<T, A, Self, F, OA> {
         crate::events::on_input(self, f)
     }
     fn on_keydown<
-        F: Fn(&mut T, &Event<web_sys::KeyboardEvent, Self::Element>) -> MessageResult<A>,
+        OA: OptionalAction<A>,
+        F: Fn(&mut T, &Event<web_sys::KeyboardEvent, Self::Element>) -> OA,
     >(
         self,
         f: F,
-    ) -> e::OnKeyDown<Self, F> {
+    ) -> e::OnKeyDown<T, A, Self, F, OA> {
         crate::events::on_keydown(self, f)
     }
 }

crates/xilem_html/web_examples/counter/src/lib.rs

@@ -1,7 +1,8 @@
 use wasm_bindgen::{prelude::*, JsValue};
 use xilem_html::{
-    document_body, elements as el, events as evt, text, App, Event, MessageResult, Text, View,
+    document_body, elements as el,
-    ViewExt,
+    events::{self as evt},
+    App, Event, View, ViewExt,
 };
 
 #[derive(Default)]
@@ -12,61 +13,54 @@ struct AppState {
 }
 
 impl AppState {
-    fn increment(&mut self) -> MessageResult<()> {
+    fn increment(&mut self) {
         self.clicks += 1;
-        MessageResult::Nop
     }
-    fn decrement(&mut self) -> MessageResult<()> {
+    fn decrement(&mut self) {
         self.clicks -= 1;
-        MessageResult::Nop
     }
-    fn reset(&mut self) -> MessageResult<()> {
+    fn reset(&mut self) {
         self.clicks = 0;
-        MessageResult::Nop
     }
-    fn change_class(&mut self) -> MessageResult<()> {
+    fn change_class(&mut self) {
         if self.class == "gray" {
             self.class = "green";
         } else {
             self.class = "gray";
         }
-        MessageResult::Nop
     }
 
-    fn change_text(&mut self) -> MessageResult<()> {
+    fn change_text(&mut self) {
         if self.text == "test" {
             self.text = "test2".into();
         } else {
             self.text = "test".into();
         }
-        MessageResult::Nop
     }
 }
 
 /// You can create functions that generate views.
-fn btn<F>(label: &'static str, click_fn: F) -> evt::OnClick<el::Button<Text>, F>
+fn btn<A, F>(
+    label: &'static str,
+    click_fn: F,
+) -> evt::OnClick<AppState, A, el::Button<&'static str>, F, ()>
 where
-    F: Fn(
+    F: Fn(&mut AppState, &Event<web_sys::MouseEvent, web_sys::HtmlButtonElement>),
-        &mut AppState,
-        &Event<web_sys::MouseEvent, web_sys::HtmlButtonElement>,
-    ) -> MessageResult<()>,
 {
-    el::button(text(label)).on_click(click_fn)
+    el::button(label).on_click(click_fn)
 }
 
 fn app_logic(state: &mut AppState) -> impl View<AppState> {
     el::div((
-        el::span(text(format!("clicked {} times", state.clicks))).attr("class", state.class),
+        el::span(format!("clicked {} times", state.clicks)).attr("class", state.class),
         el::br(()),
-        btn("+1 click", |state, _| AppState::increment(state)),
+        btn("+1 click", |state, _| state.increment()),
-        btn("-1 click", |state, _| AppState::decrement(state)),
+        btn("-1 click", |state, _| state.decrement()),
-        btn("reset clicks", |state, _| AppState::reset(state)),
+        btn("reset clicks", |state, _| state.reset()),
-        btn("a different class", |state, _| {
+        btn("a different class", |state, _| state.change_class()),
-            AppState::change_class(state)
+        btn("change text", |state, _| state.change_text()),
-        }),
-        btn("change text", |state, _| AppState::change_text(state)),
         el::br(()),
-        text(state.text.clone()),
+        state.text.clone(),
     ))
 }
 

crates/xilem_html/web_examples/counter_untyped/src/lib.rs

@@ -1,7 +1,5 @@
 use wasm_bindgen::{prelude::*, JsValue};
-use xilem_html::{
+use xilem_html::{document_body, element as el, on_event, App, Event, View, ViewMarker};
-    document_body, element as el, on_event, text, App, Event, MessageResult, View, ViewMarker,
-};
 
 #[derive(Default)]
 struct AppState {
@@ -9,32 +7,35 @@ struct AppState {
 }
 
 impl AppState {
-    fn increment(&mut self) -> MessageResult<()> {
+    fn increment(&mut self) {
         self.clicks += 1;
-        MessageResult::Nop
     }
-    fn decrement(&mut self) -> MessageResult<()> {
+    fn decrement(&mut self) {
         self.clicks -= 1;
-        MessageResult::Nop
     }
-    fn reset(&mut self) -> MessageResult<()> {
+    fn reset(&mut self) {
         self.clicks = 0;
-        MessageResult::Nop
     }
 }
 
 fn btn<F>(label: &'static str, click_fn: F) -> impl View<AppState> + ViewMarker
 where
-    F: Fn(&mut AppState, &Event<web_sys::Event, web_sys::HtmlButtonElement>) -> MessageResult<()>,
+    F: Fn(&mut AppState, &Event<web_sys::Event, web_sys::HtmlButtonElement>),
 {
-    on_event("click", el("button", text(label)), click_fn)
+    on_event(
+        "click",
+        el("button", label),
+        move |state: &mut AppState, evt: &Event<_, _>| {
+            click_fn(state, evt);
+        },
+    )
 }
 
 fn app_logic(state: &mut AppState) -> impl View<AppState> {
     el::<web_sys::HtmlElement, _>(
         "div",
         (
-            el::<web_sys::HtmlElement, _>("span", text(format!("clicked {} times", state.clicks))),
+            el::<web_sys::HtmlElement, _>("span", format!("clicked {} times", state.clicks)),
             btn("+1 click", |state, _| AppState::increment(state)),
             btn("-1 click", |state, _| AppState::decrement(state)),
             btn("reset clicks", |state, _| AppState::reset(state)),

crates/xilem_html/web_examples/todomvc/src/lib.rs

@@ -6,7 +6,8 @@ use state::{AppState, Filter, Todo};
 
 use wasm_bindgen::{prelude::*, JsValue};
 use xilem_html::{
-    elements as el, get_element_by_id, text, Adapt, App, MessageResult, View, ViewExt, ViewMarker,
+    elements as el, events::on_click, get_element_by_id, Action, Adapt, App, Event, MessageResult,
+    View, ViewExt, ViewMarker,
 };
 
 // All of these actions arise from within a `Todo`, but we need access to the full state to reduce
@@ -17,6 +18,8 @@ enum TodoAction {
     Destroy(u64),
 }
 
+impl Action for TodoAction {}
+
 fn todo_item(todo: &mut Todo, editing: bool) -> impl View<Todo, TodoAction> + ViewMarker {
     let mut class = String::new();
     if todo.completed {
@@ -36,16 +39,12 @@ fn todo_item(todo: &mut Todo, editing: bool) -> impl View<Todo, TodoAction> + Vi
         el::div((
             input.on_click(|state: &mut Todo, _| {
                 state.completed = !state.completed;
-                MessageResult::RequestRebuild
-            }),
-            el::label(text(todo.title.clone())).on_dblclick(|state: &mut Todo, _| {
-                MessageResult::Action(TodoAction::SetEditing(state.id))
             }),
+            el::label(todo.title.clone())
+                .on_dblclick(|state: &mut Todo, _| TodoAction::SetEditing(state.id)),
             el::button(())
                 .attr("class", "destroy")
-                .on_click(|state: &mut Todo, _| {
+                .on_click(|state: &mut Todo, _| TodoAction::Destroy(state.id)),
-                    MessageResult::Action(TodoAction::Destroy(state.id))
-                }),
         ))
         .attr("class", "view"),
         el::input(())
@@ -55,18 +54,17 @@ fn todo_item(todo: &mut Todo, editing: bool) -> impl View<Todo, TodoAction> + Vi
                 let key = evt.key();
                 if key == "Enter" {
                     state.save_editing();
-                    MessageResult::Action(TodoAction::CancelEditing)
+                    Some(TodoAction::CancelEditing)
                 } else if key == "Escape" {
-                    MessageResult::Action(TodoAction::CancelEditing)
+                    Some(TodoAction::CancelEditing)
                 } else {
-                    MessageResult::Nop
+                    None
                 }
             })
             .on_input(|state: &mut Todo, evt| {
                 state.title_editing.clear();
                 state.title_editing.push_str(&evt.target().value());
                 evt.prevent_default();
-                MessageResult::Nop
             }),
     ))
     .attr("class", class)
@@ -80,12 +78,12 @@ fn footer_view(state: &mut AppState) -> impl View<AppState> + ViewMarker {
     };
 
     let clear_button = (state.todos.iter().filter(|todo| todo.completed).count() > 0).then(|| {
-        el::button(text("Clear completed"))
+        on_click(
-            .attr("class", "clear-completed")
+            el::button("Clear completed").attr("class", "clear-completed"),
-            .on_click(|state: &mut AppState, _| {
+            |state: &mut AppState, _| {
                 state.todos.retain(|todo| !todo.completed);
-                MessageResult::RequestRebuild
+            },
-            })
+        )
     });
 
     let filter_class = |filter| {
@@ -98,40 +96,37 @@ fn footer_view(state: &mut AppState) -> impl View<AppState> + ViewMarker {
 
     el::footer((
         el::span((
-            el::strong(text(state.todos.len().to_string())),
+            el::strong(state.todos.len().to_string()),
-            text(format!(" {} left", item_str)),
+            format!(" {} left", item_str),
         ))
         .attr("class", "todo-count"),
         el::ul((
-            el::li(
+            el::li(on_click(
-                el::a(text("All"))
+                el::a("All")
                     .attr("href", "#/")
-                    .attr("class", filter_class(Filter::All))
+                    .attr("class", filter_class(Filter::All)),
-                    .on_click(|state: &mut AppState, _| {
+                |state: &mut AppState, _| {
-                        state.filter = Filter::All;
+                    state.filter = Filter::All;
-                        MessageResult::RequestRebuild
+                },
-                    }),
+            )),
-            ),
+            " ",
-            text(" "),
+            el::li(on_click(
-            el::li(
+                el::a("Active")
-                el::a(text("Active"))
                     .attr("href", "#/active")
-                    .attr("class", filter_class(Filter::Active))
+                    .attr("class", filter_class(Filter::Active)),
-                    .on_click(|state: &mut AppState, _| {
+                |state: &mut AppState, _| {
-                        state.filter = Filter::Active;
+                    state.filter = Filter::Active;
-                        MessageResult::RequestRebuild
+                },
-                    }),
+            )),
-            ),
+            " ",
-            text(" "),
+            el::li(on_click(
-            el::li(
+                el::a("Completed")
-                el::a(text("Completed"))
                     .attr("href", "#/completed")
-                    .attr("class", filter_class(Filter::Completed))
+                    .attr("class", filter_class(Filter::Completed)),
-                    .on_click(|state: &mut AppState, _| {
+                |state: &mut AppState, _| {
-                        state.filter = Filter::Completed;
+                    state.filter = Filter::Completed;
-                        MessageResult::RequestRebuild
+                },
-                    }),
+            )),
-            ),
         ))
         .attr("class", "filters"),
         clear_button,
@@ -177,23 +172,26 @@ fn app_logic(state: &mut AppState) -> impl View<AppState> {
     let footer = (!state.todos.is_empty()).then(|| footer_view(state));
     el::div((
         el::header((
-            el::h1(text("TODOs")),
+            el::h1("TODOs"),
             el::input(())
                 .attr("class", "new-todo")
                 .attr("placeholder", "What needs to be done?")
                 .attr("value", state.new_todo.clone())
                 .attr("autofocus", "true")
-                .on_keydown(|state: &mut AppState, evt| {
+            .on_keydown(
+                |state: &mut AppState, evt| {
                     if evt.key() == "Enter" {
                         state.create_todo();
                     }
-                    MessageResult::RequestRebuild
+                },
-                })
+            )
-                .on_input(|state: &mut AppState, evt| {
+            .on_input(
+                |state: &mut AppState,
+                 evt: &Event<web_sys::InputEvent, web_sys::HtmlInputElement>| {
                     state.update_new_todo(&evt.target().value());
                     evt.prevent_default();
-                    MessageResult::RequestRebuild
+                },
-                }),
+            ),
         ))
         .attr("class", "header"),
         main,