diff --git a/gpui/src/app.rs b/gpui/src/app.rs
index 1156ec40d4..0cf1069738 100644
--- a/gpui/src/app.rs
+++ b/gpui/src/app.rs
@@ -57,18 +57,19 @@ pub trait ReadModel {
 }
 
 pub trait ReadModelWith {
-    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
+    fn read_model_with<E: Entity, T>(
         &self,
         handle: &ModelHandle<E>,
-        read: F,
+        read: &mut dyn FnMut(&E, &AppContext) -> T,
     ) -> T;
 }
 
 pub trait UpdateModel {
-    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
-    where
-        T: Entity,
-        F: FnOnce(&mut T, &mut ModelContext<T>) -> S;
+    fn update_model<T: Entity, O>(
+        &mut self,
+        handle: &ModelHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
+    ) -> O;
 }
 
 pub trait UpgradeModelHandle {
@@ -81,17 +82,23 @@ pub trait ReadView {
 }
 
 pub trait ReadViewWith {
-    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
+    fn read_view_with<V, T>(
+        &self,
+        handle: &ViewHandle<V>,
+        read: &mut dyn FnMut(&V, &AppContext) -> T,
+    ) -> T
     where
-        V: View,
-        F: FnOnce(&V, &AppContext) -> T;
+        V: View;
 }
 
 pub trait UpdateView {
-    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
+    fn update_view<T, S>(
+        &mut self,
+        handle: &ViewHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
+    ) -> S
     where
-        T: View,
-        F: FnOnce(&mut T, &mut ViewContext<T>) -> S;
+        T: View;
 }
 
 pub trait Action: 'static + AnyAction {
@@ -531,11 +538,11 @@ impl AsyncAppContext {
 }
 
 impl UpdateModel for AsyncAppContext {
-    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
-    where
-        T: Entity,
-        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
-    {
+    fn update_model<E: Entity, O>(
+        &mut self,
+        handle: &ModelHandle<E>,
+        update: &mut dyn FnMut(&mut E, &mut ModelContext<E>) -> O,
+    ) -> O {
         let mut state = self.0.borrow_mut();
         state.pending_flushes += 1;
         let result = state.update_model(handle, update);
@@ -554,10 +561,10 @@ impl UpgradeModelHandle for AsyncAppContext {
 }
 
 impl ReadModelWith for AsyncAppContext {
-    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
+    fn read_model_with<E: Entity, T>(
         &self,
         handle: &ModelHandle<E>,
-        read: F,
+        read: &mut dyn FnMut(&E, &AppContext) -> T,
     ) -> T {
         let cx = self.0.borrow();
         let cx = cx.as_ref();
@@ -566,10 +573,13 @@ impl ReadModelWith for AsyncAppContext {
 }
 
 impl UpdateView for AsyncAppContext {
-    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
+    fn update_view<T, S>(
+        &mut self,
+        handle: &ViewHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
+    ) -> S
     where
         T: View,
-        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
     {
         let mut state = self.0.borrow_mut();
         state.pending_flushes += 1;
@@ -580,10 +590,13 @@ impl UpdateView for AsyncAppContext {
 }
 
 impl ReadViewWith for AsyncAppContext {
-    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
+    fn read_view_with<V, T>(
+        &self,
+        handle: &ViewHandle<V>,
+        read: &mut dyn FnMut(&V, &AppContext) -> T,
+    ) -> T
     where
         V: View,
-        F: FnOnce(&V, &AppContext) -> T,
     {
         let cx = self.0.borrow();
         let cx = cx.as_ref();
@@ -592,11 +605,11 @@ impl ReadViewWith for AsyncAppContext {
 }
 
 impl UpdateModel for TestAppContext {
-    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
-    where
-        T: Entity,
-        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
-    {
+    fn update_model<T: Entity, O>(
+        &mut self,
+        handle: &ModelHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
+    ) -> O {
         let mut state = self.cx.borrow_mut();
         state.pending_flushes += 1;
         let result = state.update_model(handle, update);
@@ -606,10 +619,10 @@ impl UpdateModel for TestAppContext {
 }
 
 impl ReadModelWith for TestAppContext {
-    fn read_model_with<E: Entity, F: FnOnce(&E, &AppContext) -> T, T>(
+    fn read_model_with<E: Entity, T>(
         &self,
         handle: &ModelHandle<E>,
-        read: F,
+        read: &mut dyn FnMut(&E, &AppContext) -> T,
     ) -> T {
         let cx = self.cx.borrow();
         let cx = cx.as_ref();
@@ -618,10 +631,13 @@ impl ReadModelWith for TestAppContext {
 }
 
 impl UpdateView for TestAppContext {
-    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
+    fn update_view<T, S>(
+        &mut self,
+        handle: &ViewHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
+    ) -> S
     where
         T: View,
-        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
     {
         let mut state = self.cx.borrow_mut();
         state.pending_flushes += 1;
@@ -632,10 +648,13 @@ impl UpdateView for TestAppContext {
 }
 
 impl ReadViewWith for TestAppContext {
-    fn read_view_with<V, F, T>(&self, handle: &ViewHandle<V>, read: F) -> T
+    fn read_view_with<V, T>(
+        &self,
+        handle: &ViewHandle<V>,
+        read: &mut dyn FnMut(&V, &AppContext) -> T,
+    ) -> T
     where
         V: View,
-        F: FnOnce(&V, &AppContext) -> T,
     {
         let cx = self.cx.borrow();
         let cx = cx.as_ref();
@@ -1629,11 +1648,11 @@ impl ReadModel for MutableAppContext {
 }
 
 impl UpdateModel for MutableAppContext {
-    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
-    where
-        T: Entity,
-        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
-    {
+    fn update_model<T: Entity, V>(
+        &mut self,
+        handle: &ModelHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
+    ) -> V {
         if let Some(mut model) = self.cx.models.remove(&handle.model_id) {
             self.pending_flushes += 1;
             let mut cx = ModelContext::new(self, handle.model_id);
@@ -1673,10 +1692,13 @@ impl ReadView for MutableAppContext {
 }
 
 impl UpdateView for MutableAppContext {
-    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
+    fn update_view<T, S>(
+        &mut self,
+        handle: &ViewHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
+    ) -> S
     where
         T: View,
-        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
     {
         self.pending_flushes += 1;
         let mut view = self
@@ -2083,11 +2105,11 @@ impl<M> ReadModel for ModelContext<'_, M> {
 }
 
 impl<M> UpdateModel for ModelContext<'_, M> {
-    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
-    where
-        T: Entity,
-        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
-    {
+    fn update_model<T: Entity, V>(
+        &mut self,
+        handle: &ModelHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> V,
+    ) -> V {
         self.app.update_model(handle, update)
     }
 }
@@ -2344,11 +2366,11 @@ impl<V: View> ReadModel for RenderContext<'_, V> {
 }
 
 impl<V: View> UpdateModel for RenderContext<'_, V> {
-    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
-    where
-        T: Entity,
-        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
-    {
+    fn update_model<T: Entity, O>(
+        &mut self,
+        handle: &ModelHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
+    ) -> O {
         self.app.update_model(handle, update)
     }
 }
@@ -2395,11 +2417,11 @@ impl<V> UpgradeModelHandle for ViewContext<'_, V> {
 }
 
 impl<V: View> UpdateModel for ViewContext<'_, V> {
-    fn update_model<T, F, S>(&mut self, handle: &ModelHandle<T>, update: F) -> S
-    where
-        T: Entity,
-        F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
-    {
+    fn update_model<T: Entity, O>(
+        &mut self,
+        handle: &ModelHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ModelContext<T>) -> O,
+    ) -> O {
         self.app.update_model(handle, update)
     }
 }
@@ -2411,10 +2433,13 @@ impl<V: View> ReadView for ViewContext<'_, V> {
 }
 
 impl<V: View> UpdateView for ViewContext<'_, V> {
-    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
+    fn update_view<T, S>(
+        &mut self,
+        handle: &ViewHandle<T>,
+        update: &mut dyn FnMut(&mut T, &mut ViewContext<T>) -> S,
+    ) -> S
     where
         T: View,
-        F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
     {
         self.app.update_view(handle, update)
     }
@@ -2469,7 +2494,11 @@ impl<T: Entity> ModelHandle<T> {
         C: ReadModelWith,
         F: FnOnce(&T, &AppContext) -> S,
     {
-        cx.read_model_with(self, read)
+        let mut read = Some(read);
+        cx.read_model_with(self, &mut |model, cx| {
+            let read = read.take().unwrap();
+            read(model, cx)
+        })
     }
 
     pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
@@ -2477,7 +2506,11 @@ impl<T: Entity> ModelHandle<T> {
         C: UpdateModel,
         F: FnOnce(&mut T, &mut ModelContext<T>) -> S,
     {
-        cx.update_model(self, update)
+        let mut update = Some(update);
+        cx.update_model(self, &mut |model, cx| {
+            let update = update.take().unwrap();
+            update(model, cx)
+        })
     }
 
     pub fn next_notification(&self, cx: &TestAppContext) -> impl Future<Output = ()> {
@@ -2743,7 +2776,11 @@ impl<T: View> ViewHandle<T> {
         C: ReadViewWith,
         F: FnOnce(&T, &AppContext) -> S,
     {
-        cx.read_view_with(self, read)
+        let mut read = Some(read);
+        cx.read_view_with(self, &mut |view, cx| {
+            let read = read.take().unwrap();
+            read(view, cx)
+        })
     }
 
     pub fn update<C, F, S>(&self, cx: &mut C, update: F) -> S
@@ -2751,7 +2788,11 @@ impl<T: View> ViewHandle<T> {
         C: UpdateView,
         F: FnOnce(&mut T, &mut ViewContext<T>) -> S,
     {
-        cx.update_view(self, update)
+        let mut update = Some(update);
+        cx.update_view(self, &mut |view, cx| {
+            let update = update.take().unwrap();
+            update(view, cx)
+        })
     }
 
     pub fn is_focused(&self, cx: &AppContext) -> bool {
diff --git a/gpui/src/presenter.rs b/gpui/src/presenter.rs
index 8bcdd08aad..354f0a0f82 100644
--- a/gpui/src/presenter.rs
+++ b/gpui/src/presenter.rs
@@ -7,7 +7,7 @@ use crate::{
     platform::Event,
     text_layout::TextLayoutCache,
     Action, AnyAction, AssetCache, ElementBox, Entity, FontSystem, ModelHandle, ReadModel,
-    ReadView, Scene, UpdateView, View, ViewHandle,
+    ReadView, Scene, View, ViewHandle,
 };
 use pathfinder_geometry::vector::{vec2f, Vector2F};
 use serde_json::json;
@@ -264,16 +264,6 @@ impl<'a> ReadView for LayoutContext<'a> {
     }
 }
 
-impl<'a> UpdateView for LayoutContext<'a> {
-    fn update_view<T, F, S>(&mut self, handle: &ViewHandle<T>, update: F) -> S
-    where
-        T: View,
-        F: FnOnce(&mut T, &mut crate::ViewContext<T>) -> S,
-    {
-        self.app.update_view(handle, update)
-    }
-}
-
 impl<'a> ReadModel for LayoutContext<'a> {
     fn read_model<T: Entity>(&self, handle: &ModelHandle<T>) -> &T {
         self.app.read_model(handle)