Merge pull request #1910 from ealmloff/readable-map

Implement Readable for mapped signal

packages/generational-box/src/lib.rs

@@ -228,9 +228,9 @@ pub trait Storage<Data = ()>: AnyStorage + 'static {
 /// A trait for any storage backing type.
 pub trait AnyStorage: Default {
     /// The reference this storage type returns.
-    type Ref<T: ?Sized + 'static>: Deref<Target = T>;
+    type Ref<T: ?Sized + 'static>: Deref<Target = T> + 'static;
     /// The mutable reference this storage type returns.
-    type Mut<T: ?Sized + 'static>: DerefMut<Target = T>;
+    type Mut<T: ?Sized + 'static>: DerefMut<Target = T> + 'static;
 
     /// Try to map the mutable ref.
     fn try_map_mut<T: ?Sized, U: ?Sized + 'static>(
@@ -247,13 +247,16 @@ pub trait AnyStorage: Default {
     }
 
     /// Try to map the ref.
-    fn try_map<T, U: ?Sized + 'static>(
+    fn try_map<T: ?Sized, U: ?Sized + 'static>(
         ref_: Self::Ref<T>,
         f: impl FnOnce(&T) -> Option<&U>,
     ) -> Option<Self::Ref<U>>;
 
     /// Map the ref.
-    fn map<T, U: ?Sized + 'static>(ref_: Self::Ref<T>, f: impl FnOnce(&T) -> &U) -> Self::Ref<U> {
+    fn map<T: ?Sized, U: ?Sized + 'static>(
+        ref_: Self::Ref<T>,
+        f: impl FnOnce(&T) -> &U,
+    ) -> Self::Ref<U> {
         Self::try_map(ref_, |v| Some(f(v))).unwrap()
     }
 

packages/generational-box/src/sync.rs

@@ -23,7 +23,7 @@ impl AnyStorage for SyncStorage {
     type Ref<R: ?Sized + 'static> = GenerationalRef<MappedRwLockReadGuard<'static, R>>;
     type Mut<W: ?Sized + 'static> = GenerationalRefMut<MappedRwLockWriteGuard<'static, W>>;
 
-    fn try_map<I, U: ?Sized + 'static>(
+    fn try_map<I: ?Sized, U: ?Sized + 'static>(
         ref_: Self::Ref<I>,
         f: impl FnOnce(&I) -> Option<&U>,
     ) -> Option<Self::Ref<U>> {

packages/generational-box/src/unsync.rs

@@ -92,7 +92,7 @@ impl AnyStorage for UnsyncStorage {
     type Ref<R: ?Sized + 'static> = GenerationalRef<Ref<'static, R>>;
     type Mut<W: ?Sized + 'static> = GenerationalRefMut<RefMut<'static, W>>;
 
-    fn try_map<I, U: ?Sized + 'static>(
+    fn try_map<I: ?Sized, U: ?Sized + 'static>(
         _self: Self::Ref<I>,
         f: impl FnOnce(&I) -> Option<&U>,
     ) -> Option<Self::Ref<U>> {

packages/signals/Cargo.toml

@@ -26,7 +26,6 @@ flume = { version = "0.11.0", default-features = false, features = ["async"] }
 
 [dev-dependencies]
 dioxus = { workspace = true }
-# dioxus-desktop = { workspace = true }
 tokio = { version = "1", features = ["full"] }
 tracing-subscriber = "0.3.17"
 simple_logger = "4.2.0"

packages/signals/examples/map_signal.rs

@@ -0,0 +1,50 @@
+#![allow(non_snake_case)]
+
+use dioxus::prelude::*;
+
+fn main() {
+    launch(app);
+}
+
+fn app() -> Element {
+    let mut vec = use_signal(|| vec![0]);
+
+    rsx! {
+        button {
+            onclick: move |_| {
+                let mut write = vec.write();
+                let len = write.len() as i32;
+                write.push(len);
+            },
+            "Create"
+        }
+
+        button {
+            onclick: move |_| {
+                vec.write().pop();
+            },
+            "Destroy"
+        }
+
+        for i in 0..vec.len() {
+            Child { count: vec.map(move |v| &v[i]) }
+        }
+    }
+}
+
+#[component]
+fn Child(count: MappedSignal<i32>) -> Element {
+    use_memo({
+        to_owned![count];
+        move || {
+            let value = count.read();
+            println!("Child value: {value}");
+        }
+    });
+
+    rsx! {
+        div {
+            "Child: {count}"
+        }
+    }
+}

packages/signals/src/copy_value.rs

@@ -13,6 +13,7 @@ use dioxus_core::ScopeId;
 
 use generational_box::{GenerationalBox, Owner, Storage};
 
+use crate::ReadableRef;
 use crate::Writable;
 use crate::{ReactiveContext, Readable};
 
@@ -204,40 +205,30 @@ impl<T: 'static, S: Storage<T>> CopyValue<T, S> {
     }
 }
 
-impl<T: 'static, S: Storage<T>> Readable<T> for CopyValue<T, S> {
-    type Ref<R: ?Sized + 'static> = S::Ref<R>;
+impl<T: 'static, S: Storage<T>> Readable for CopyValue<T, S> {
+    type Target = T;
+    type Storage = S;
 
-    fn map_ref<I, U: ?Sized, F: FnOnce(&I) -> &U>(ref_: Self::Ref<I>, f: F) -> Self::Ref<U> {
-        S::map(ref_, f)
-    }
-
-    fn try_map_ref<I, U: ?Sized, F: FnOnce(&I) -> Option<&U>>(
-        ref_: Self::Ref<I>,
-        f: F,
-    ) -> Option<Self::Ref<U>> {
-        S::try_map(ref_, f)
-    }
-
-    fn try_read(&self) -> Result<S::Ref<T>, generational_box::BorrowError> {
+    fn try_read(&self) -> Result<ReadableRef<Self>, generational_box::BorrowError> {
         self.value.try_read()
     }
 
-    fn peek(&self) -> Self::Ref<T> {
+    fn peek(&self) -> ReadableRef<Self> {
         self.value.read()
     }
 }
 
-impl<T: 'static, S: Storage<T>> Writable<T> for CopyValue<T, S> {
+impl<T: 'static, S: Storage<T>> Writable for CopyValue<T, S> {
     type Mut<R: ?Sized + 'static> = S::Mut<R>;
 
-    fn map_mut<I, U: ?Sized, F: FnOnce(&mut I) -> &mut U>(
+    fn map_mut<I: ?Sized, U: ?Sized, F: FnOnce(&mut I) -> &mut U>(
         mut_: Self::Mut<I>,
         f: F,
     ) -> Self::Mut<U> {
         S::map_mut(mut_, f)
     }
 
-    fn try_map_mut<I, U: ?Sized, F: FnOnce(&mut I) -> Option<&mut U>>(
+    fn try_map_mut<I: ?Sized, U: ?Sized, F: FnOnce(&mut I) -> Option<&mut U>>(
         mut_: Self::Mut<I>,
         f: F,
     ) -> Option<Self::Mut<U>> {

packages/signals/src/global/memo.rs

@@ -1,6 +1,6 @@
-use crate::read::Readable;
+use crate::{read::Readable, ReadableRef};
 use dioxus_core::prelude::{IntoAttributeValue, ScopeId};
-use generational_box::{AnyStorage, UnsyncStorage};
+use generational_box::UnsyncStorage;
 use std::{mem::MaybeUninit, ops::Deref};
 
 use crate::{ReadOnlySignal, Signal};
@@ -51,27 +51,17 @@ impl<T: PartialEq + 'static> GlobalMemo<T> {
     }
 }
 
-impl<T: PartialEq + 'static> Readable<T> for GlobalMemo<T> {
-    type Ref<R: ?Sized + 'static> = generational_box::GenerationalRef<std::cell::Ref<'static, R>>;
-
-    fn map_ref<I, U: ?Sized, F: FnOnce(&I) -> &U>(ref_: Self::Ref<I>, f: F) -> Self::Ref<U> {
-        <UnsyncStorage as AnyStorage>::map(ref_, f)
-    }
-
-    fn try_map_ref<I, U: ?Sized, F: FnOnce(&I) -> Option<&U>>(
-        ref_: Self::Ref<I>,
-        f: F,
-    ) -> Option<Self::Ref<U>> {
-        <UnsyncStorage as AnyStorage>::try_map(ref_, f)
-    }
+impl<T: PartialEq + 'static> Readable for GlobalMemo<T> {
+    type Target = T;
+    type Storage = UnsyncStorage;
 
     #[track_caller]
-    fn try_read(&self) -> Result<Self::Ref<T>, generational_box::BorrowError> {
+    fn try_read(&self) -> Result<ReadableRef<Self>, generational_box::BorrowError> {
         self.signal().try_read()
     }
 
     #[track_caller]
-    fn peek(&self) -> Self::Ref<T> {
+    fn peek(&self) -> ReadableRef<Self> {
         self.signal().peek()
     }
 }

packages/signals/src/global/signal.rs

@@ -1,12 +1,12 @@
-use crate::read::Readable;
 use crate::write::Writable;
 use crate::Write;
+use crate::{read::Readable, ReadableRef};
 use dioxus_core::prelude::{IntoAttributeValue, ScopeId};
-use generational_box::{AnyStorage, GenerationalRef, UnsyncStorage};
-use std::{cell::Ref, mem::MaybeUninit, ops::Deref};
+use generational_box::UnsyncStorage;
+use std::{mem::MaybeUninit, ops::Deref};
 
 use super::get_global_context;
-use crate::{MappedSignal, Signal};
+use crate::Signal;
 
 /// A signal that can be accessed from anywhere in the application and created in a static
 pub struct GlobalSignal<T> {
@@ -60,56 +60,42 @@ impl<T: 'static> GlobalSignal<T> {
         self.signal().with_mut(f)
     }
 
-    /// Map the signal to a new type.
-    pub fn map<O>(
-        &self,
-        f: impl Fn(&T) -> &O + 'static,
-    ) -> MappedSignal<GenerationalRef<Ref<'static, O>>> {
-        MappedSignal::new(self.signal(), f)
-    }
-
     /// Get the generational id of the signal.
     pub fn id(&self) -> generational_box::GenerationalBoxId {
         self.signal().id()
     }
 }
 
-impl<T: 'static> Readable<T> for GlobalSignal<T> {
-    type Ref<R: ?Sized + 'static> = generational_box::GenerationalRef<std::cell::Ref<'static, R>>;
-
-    fn map_ref<I, U: ?Sized, F: FnOnce(&I) -> &U>(ref_: Self::Ref<I>, f: F) -> Self::Ref<U> {
-        <UnsyncStorage as AnyStorage>::map(ref_, f)
-    }
-
-    fn try_map_ref<I, U: ?Sized, F: FnOnce(&I) -> Option<&U>>(
-        ref_: Self::Ref<I>,
-        f: F,
-    ) -> Option<Self::Ref<U>> {
-        <UnsyncStorage as AnyStorage>::try_map(ref_, f)
-    }
+impl<T: 'static> Readable for GlobalSignal<T> {
+    type Target = T;
+    type Storage = UnsyncStorage;
 
     #[track_caller]
-    fn try_read(&self) -> Result<Self::Ref<T>, generational_box::BorrowError> {
+    fn try_read(&self) -> Result<ReadableRef<Self>, generational_box::BorrowError> {
         self.signal().try_read()
     }
 
     #[track_caller]
-    fn peek(&self) -> Self::Ref<T> {
+    fn peek(&self) -> ReadableRef<Self> {
         self.signal().peek()
     }
 }
 
-impl<T: 'static> Writable<T> for GlobalSignal<T> {
+impl<T: 'static> Writable for GlobalSignal<T> {
     type Mut<R: ?Sized + 'static> = Write<R, UnsyncStorage>;
 
-    fn map_mut<I, U: ?Sized + 'static, F: FnOnce(&mut I) -> &mut U>(
+    fn map_mut<I: ?Sized, U: ?Sized + 'static, F: FnOnce(&mut I) -> &mut U>(
         ref_: Self::Mut<I>,
         f: F,
     ) -> Self::Mut<U> {
         Write::map(ref_, f)
     }
 
-    fn try_map_mut<I: 'static, U: ?Sized + 'static, F: FnOnce(&mut I) -> Option<&mut U>>(
+    fn try_map_mut<
+        I: ?Sized + 'static,
+        U: ?Sized + 'static,
+        F: FnOnce(&mut I) -> Option<&mut U>,
+    >(
         ref_: Self::Mut<I>,
         f: F,
     ) -> Option<Self::Mut<U>> {
@@ -151,7 +137,7 @@ impl<T: Clone + 'static> Deref for GlobalSignal<T> {
 
         // Then move that value into the closure. We assume that the closure now has a in memory layout of Self.
         let uninit_closure = move || {
-            <GlobalSignal<T> as Readable<T>>::read(unsafe { &*uninit_callable.as_ptr() }).clone()
+            <GlobalSignal<T> as Readable>::read(unsafe { &*uninit_callable.as_ptr() }).clone()
         };
 
         // Check that the size of the closure is the same as the size of Self in case the compiler changed the layout of the closure.

packages/signals/src/impls.rs

@@ -2,15 +2,15 @@ use crate::copy_value::CopyValue;
 use crate::read::Readable;
 use crate::signal::Signal;
 use crate::write::Writable;
-use crate::{GlobalMemo, GlobalSignal, ReadOnlySignal, SignalData};
-use generational_box::Storage;
+use crate::{GlobalMemo, GlobalSignal, MappedSignal, ReadOnlySignal, SignalData};
+use generational_box::{AnyStorage, Storage};
 
 use std::{
     fmt::{Debug, Display},
     ops::{Add, Div, Mul, Sub},
 };
 
-macro_rules! read_impls {
+macro_rules! default_impl {
     ($ty:ident $(: $extra_bounds:path)? $(, $bound_ty:ident : $bound:path, $vec_bound_ty:ident : $vec_bound:path)?) => {
         $(
             impl<T: Default + 'static, $bound_ty: $bound> Default for $ty<T, $bound_ty> {
@@ -20,7 +20,11 @@ macro_rules! read_impls {
                 }
             }
         )?
+    }
+}
 
+macro_rules! read_impls {
+    ($ty:ident $(: $extra_bounds:path)? $(, $bound_ty:ident : $bound:path, $vec_bound_ty:ident : $vec_bound:path)?) => {
         impl<T: $($extra_bounds + )? Display + 'static $(,$bound_ty: $bound)?> Display for $ty<T $(, $bound_ty)?> {
             #[track_caller]
             fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
@@ -113,6 +117,7 @@ macro_rules! write_impls {
 }
 
 read_impls!(CopyValue, S: Storage<T>, S: Storage<Vec<T>>);
+default_impl!(CopyValue, S: Storage<T>, S: Storage<Vec<T>>);
 write_impls!(CopyValue, Storage<T>, Storage<Vec<T>>);
 
 impl<T: 'static, S: Storage<T>> Clone for CopyValue<T, S> {
@@ -124,6 +129,7 @@ impl<T: 'static, S: Storage<T>> Clone for CopyValue<T, S> {
 impl<T: 'static, S: Storage<T>> Copy for CopyValue<T, S> {}
 
 read_impls!(Signal, S: Storage<SignalData<T>>, S: Storage<SignalData<Vec<T>>>);
+default_impl!(Signal, S: Storage<SignalData<T>>, S: Storage<SignalData<Vec<T>>>);
 write_impls!(Signal, Storage<SignalData<T>>, Storage<SignalData<Vec<T>>>);
 
 impl<T: 'static, S: Storage<SignalData<T>>> Clone for Signal<T, S> {
@@ -139,6 +145,11 @@ read_impls!(
     S: Storage<SignalData<T>>,
     S: Storage<SignalData<Vec<T>>>
 );
+default_impl!(
+    ReadOnlySignal,
+    S: Storage<SignalData<T>>,
+    S: Storage<SignalData<Vec<T>>>
+);
 
 impl<T: 'static, S: Storage<SignalData<T>>> Clone for ReadOnlySignal<T, S> {
     fn clone(&self) -> Self {
@@ -149,5 +160,8 @@ impl<T: 'static, S: Storage<SignalData<T>>> Clone for ReadOnlySignal<T, S> {
 impl<T: 'static, S: Storage<SignalData<T>>> Copy for ReadOnlySignal<T, S> {}
 
 read_impls!(GlobalSignal);
+default_impl!(GlobalSignal);
 
 read_impls!(GlobalMemo: PartialEq);
+
+read_impls!(MappedSignal, S: AnyStorage, S: AnyStorage);

packages/signals/src/map.rs

@@ -1,114 +1,86 @@
-use crate::read::Readable;
-use crate::CopyValue;
-use crate::Signal;
-use crate::SignalData;
-use dioxus_core::ScopeId;
-use generational_box::Storage;
-use std::fmt::Debug;
-use std::fmt::Display;
+use std::{ops::Deref, rc::Rc};
+
+use crate::{read::Readable, ReadableRef};
+use dioxus_core::prelude::*;
+use generational_box::{AnyStorage, UnsyncStorage};
 
 /// A read only signal that has been mapped to a new type.
-pub struct MappedSignal<U: 'static + ?Sized> {
-    origin_scope: ScopeId,
-    mapping: CopyValue<Box<dyn Fn() -> U>>,
+pub struct MappedSignal<O: ?Sized + 'static, S: AnyStorage = UnsyncStorage> {
+    try_read: Rc<dyn Fn() -> Result<S::Ref<O>, generational_box::BorrowError> + 'static>,
+    peek: Rc<dyn Fn() -> S::Ref<O> + 'static>,
 }
 
-impl MappedSignal<()> {
-    /// Create a new mapped signal.
-    pub fn new<T, S, U>(
-        signal: Signal<T, S>,
-        mapping: impl Fn(&T) -> &U + 'static,
-    ) -> MappedSignal<S::Ref<U>>
-    where
-        S: Storage<SignalData<T>>,
-        U: ?Sized,
-    {
+impl<O: ?Sized, S: AnyStorage> Clone for MappedSignal<O, S> {
+    fn clone(&self) -> Self {
         MappedSignal {
-            origin_scope: signal.origin_scope(),
-            mapping: CopyValue::new(Box::new(move || S::map(signal.read(), &mapping))),
+            try_read: self.try_read.clone(),
+            peek: self.peek.clone(),
         }
     }
 }
 
-impl<U> MappedSignal<U> {
-    /// Get the scope that the signal was created in.
-    pub fn origin_scope(&self) -> ScopeId {
-        self.origin_scope
-    }
-
-    /// Get the current value of the signal. This will subscribe the current scope to the signal.
-    pub fn read(&self) -> U {
-        (self.mapping.read())()
-    }
-
-    /// Run a closure with a reference to the signal's value.
-    pub fn with<O>(&self, f: impl FnOnce(U) -> O) -> O {
-        f(self.read())
+impl<O, S> MappedSignal<O, S>
+where
+    O: ?Sized,
+    S: AnyStorage,
+{
+    /// Create a new mapped signal.
+    pub(crate) fn new(
+        try_read: Rc<dyn Fn() -> Result<S::Ref<O>, generational_box::BorrowError> + 'static>,
+        peek: Rc<dyn Fn() -> S::Ref<O> + 'static>,
+    ) -> Self {
+        MappedSignal { try_read, peek }
     }
 }
 
-impl<U: ?Sized + Clone> MappedSignal<U> {
-    /// Get the current value of the signal. This will subscribe the current scope to the signal.
-    pub fn value(&self) -> U {
-        self.read().clone()
+impl<O, S> Readable for MappedSignal<O, S>
+where
+    O: ?Sized,
+    S: AnyStorage,
+{
+    type Target = O;
+    type Storage = S;
+
+    fn try_read(&self) -> Result<ReadableRef<Self>, generational_box::BorrowError> {
+        (self.try_read)()
+    }
+
+    fn peek(&self) -> ReadableRef<Self> {
+        (self.peek)()
     }
 }
 
-impl<U: ?Sized> PartialEq for MappedSignal<U> {
+impl<O, S> IntoAttributeValue for MappedSignal<O, S>
+where
+    O: Clone + IntoAttributeValue,
+    S: AnyStorage,
+{
+    fn into_value(self) -> dioxus_core::AttributeValue {
+        self.with(|f| f.clone().into_value())
+    }
+}
+
+impl<O, S> PartialEq for MappedSignal<O, S>
+where
+    O: ?Sized,
+    S: AnyStorage,
+{
     fn eq(&self, other: &Self) -> bool {
-        self.mapping == other.mapping
+        std::ptr::eq(&self.peek, &other.peek) && std::ptr::eq(&self.try_read, &other.try_read)
     }
 }
 
-impl<U> std::clone::Clone for MappedSignal<U> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-
-impl<U> Copy for MappedSignal<U> {}
-
-impl<U: Display> Display for MappedSignal<U> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        self.with(|v| Display::fmt(&v, f))
-    }
-}
-
-impl<U: Debug> Debug for MappedSignal<U> {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        self.with(|v| Debug::fmt(&v, f))
-    }
-}
-
-impl<T> std::ops::Deref for MappedSignal<T> {
-    type Target = dyn Fn() -> T;
+/// Allow calling a signal with signal() syntax
+///
+/// Currently only limited to copy types, though could probably specialize for string/arc/rc
+impl<O, S> Deref for MappedSignal<O, S>
+where
+    O: Clone,
+    S: AnyStorage + 'static,
+{
+    type Target = dyn Fn() -> O;
 
     fn deref(&self) -> &Self::Target {
-        // https://github.com/dtolnay/case-studies/tree/master/callable-types
-
-        // First we create a closure that captures something with the Same in memory layout as Self (MaybeUninit<Self>).
-        let uninit_callable = std::mem::MaybeUninit::<Self>::uninit();
-        // Then move that value into the closure. We assume that the closure now has a in memory layout of Self.
-        let uninit_closure = move || Self::read(unsafe { &*uninit_callable.as_ptr() });
-
-        // Check that the size of the closure is the same as the size of Self in case the compiler changed the layout of the closure.
-        let size_of_closure = std::mem::size_of_val(&uninit_closure);
-        assert_eq!(size_of_closure, std::mem::size_of::<Self>());
-
-        // Then cast the lifetime of the closure to the lifetime of &self.
-        fn cast_lifetime<'a, T>(_a: &T, b: &'a T) -> &'a T {
-            b
-        }
-        let reference_to_closure = cast_lifetime(
-            {
-                // The real closure that we will never use.
-                &uninit_closure
-            },
-            // We transmute self into a reference to the closure. This is safe because we know that the closure has the same memory layout as Self so &Closure == &Self.
-            unsafe { std::mem::transmute(self) },
-        );
-
-        // Cast the closure to a trait object.
-        reference_to_closure as &Self::Target
+        Readable::deref_impl(self)
     }
 }

packages/signals/src/read.rs

@@ -1,66 +1,92 @@
-use std::{mem::MaybeUninit, ops::Deref};
+use std::{mem::MaybeUninit, ops::Index, rc::Rc};
+
+use generational_box::AnyStorage;
+
+use crate::MappedSignal;
+
+/// A reference to a value that can be read from.
+#[allow(type_alias_bounds)]
+pub type ReadableRef<T: Readable, O = <T as Readable>::Target> = <T::Storage as AnyStorage>::Ref<O>;
 
 /// A trait for states that can be read from like [`crate::Signal`], [`crate::GlobalSignal`], or [`crate::ReadOnlySignal`]. You may choose to accept this trait as a parameter instead of the concrete type to allow for more flexibility in your API. For example, instead of creating two functions, one that accepts a [`crate::Signal`] and one that accepts a [`crate::GlobalSignal`], you can create one function that accepts a [`Readable`] type.
-pub trait Readable<T: 'static = ()> {
-    /// The type of the reference.
-    type Ref<R: ?Sized + 'static>: Deref<Target = R>;
+pub trait Readable {
+    /// The target type of the reference.
+    type Target: ?Sized + 'static;
 
-    /// Map the reference to a new type.
-    fn map_ref<I, U: ?Sized, F: FnOnce(&I) -> &U>(ref_: Self::Ref<I>, f: F) -> Self::Ref<U>;
+    /// The type of the storage this readable uses.
+    type Storage: AnyStorage;
 
-    /// Try to map the reference to a new type.
-    fn try_map_ref<I, U: ?Sized, F: FnOnce(&I) -> Option<&U>>(
-        ref_: Self::Ref<I>,
-        f: F,
-    ) -> Option<Self::Ref<U>>;
-
-    /// Try to get the current value of the state. If this is a signal, this will subscribe the current scope to the signal. If the value has been dropped, this will panic.
-    fn try_read(&self) -> Result<Self::Ref<T>, generational_box::BorrowError>;
+    /// Map the readable type to a new type.
+    fn map<O>(self, f: impl Fn(&Self::Target) -> &O + 'static) -> MappedSignal<O, Self::Storage>
+    where
+        Self: Clone + Sized + 'static,
+    {
+        let mapping = Rc::new(f);
+        let try_read = Rc::new({
+            let self_ = self.clone();
+            let mapping = mapping.clone();
+            move || {
+                self_
+                    .try_read()
+                    .map(|ref_| <Self::Storage as AnyStorage>::map(ref_, |r| mapping(r)))
+            }
+        })
+            as Rc<
+                dyn Fn() -> Result<ReadableRef<Self, O>, generational_box::BorrowError> + 'static,
+            >;
+        let peek = Rc::new(move || <Self::Storage as AnyStorage>::map(self.peek(), |r| mapping(r)))
+            as Rc<dyn Fn() -> ReadableRef<Self, O> + 'static>;
+        MappedSignal::new(try_read, peek)
+    }
 
     /// Get the current value of the state. If this is a signal, this will subscribe the current scope to the signal. If the value has been dropped, this will panic.
     #[track_caller]
-    fn read(&self) -> Self::Ref<T> {
+    fn read(&self) -> ReadableRef<Self> {
         self.try_read().unwrap()
     }
 
+    /// Try to get the current value of the state. If this is a signal, this will subscribe the current scope to the signal. If the value has been dropped, this will panic.
+    #[track_caller]
+    fn try_read(&self) -> Result<ReadableRef<Self>, generational_box::BorrowError>;
+
     /// Get the current value of the state without subscribing to updates. If the value has been dropped, this will panic.
-    fn peek(&self) -> Self::Ref<T>;
+    fn peek(&self) -> ReadableRef<Self>;
 
     /// Clone the inner value and return it. If the value has been dropped, this will panic.
     #[track_caller]
-    fn cloned(&self) -> T
+    fn cloned(&self) -> Self::Target
     where
-        T: Clone,
+        Self::Target: Clone,
     {
         self.read().clone()
     }
 
     /// Run a function with a reference to the value. If the value has been dropped, this will panic.
     #[track_caller]
-    fn with<O>(&self, f: impl FnOnce(&T) -> O) -> O {
+    fn with<O>(&self, f: impl FnOnce(&Self::Target) -> O) -> O {
         f(&*self.read())
     }
 
     /// Run a function with a reference to the value. If the value has been dropped, this will panic.
     #[track_caller]
-    fn with_peek<O>(&self, f: impl FnOnce(&T) -> O) -> O {
+    fn with_peek<O>(&self, f: impl FnOnce(&Self::Target) -> O) -> O {
         f(&*self.peek())
     }
 
     /// Index into the inner value and return a reference to the result. If the value has been dropped or the index is invalid, this will panic.
     #[track_caller]
-    fn index<I>(&self, index: I) -> Self::Ref<T::Output>
+    fn index<I>(&self, index: I) -> ReadableRef<Self, <Self::Target as std::ops::Index<I>>::Output>
     where
-        T: std::ops::Index<I>,
+        Self::Target: std::ops::Index<I>,
     {
-        Self::map_ref(self.read(), |v| v.index(index))
+        <Self::Storage as AnyStorage>::map(self.read(), |v| v.index(index))
     }
 
     #[doc(hidden)]
-    fn deref_impl<'a>(&self) -> &'a dyn Fn() -> T
+    fn deref_impl<'a>(&self) -> &'a dyn Fn() -> Self::Target
     where
         Self: Sized + 'a,
-        T: Clone,
+        Self::Target: Clone,
     {
         // https://github.com/dtolnay/case-studies/tree/master/callable-types
 
@@ -92,7 +118,7 @@ pub trait Readable<T: 'static = ()> {
 }
 
 /// An extension trait for Readable<Vec<T>> that provides some convenience methods.
-pub trait ReadableVecExt<T: 'static>: Readable<Vec<T>> {
+pub trait ReadableVecExt<T: 'static>: Readable<Target = Vec<T>> {
     /// Returns the length of the inner vector.
     #[track_caller]
     fn len(&self) -> usize {
@@ -107,45 +133,43 @@ pub trait ReadableVecExt<T: 'static>: Readable<Vec<T>> {
 
     /// Get the first element of the inner vector.
     #[track_caller]
-    fn first(&self) -> Option<Self::Ref<T>> {
-        Self::try_map_ref(self.read(), |v| v.first())
+    fn first(&self) -> Option<ReadableRef<Self, T>> {
+        <Self::Storage as AnyStorage>::try_map(self.read(), |v| v.first())
     }
 
     /// Get the last element of the inner vector.
     #[track_caller]
-    fn last(&self) -> Option<Self::Ref<T>> {
-        Self::try_map_ref(self.read(), |v| v.last())
+    fn last(&self) -> Option<ReadableRef<Self, T>> {
+        <Self::Storage as AnyStorage>::try_map(self.read(), |v| v.last())
     }
 
     /// Get the element at the given index of the inner vector.
     #[track_caller]
-    fn get(&self, index: usize) -> Option<Self::Ref<T>> {
-        Self::try_map_ref(self.read(), |v| v.get(index))
+    fn get(&self, index: usize) -> Option<ReadableRef<Self, T>> {
+        <Self::Storage as AnyStorage>::try_map(self.read(), |v| v.get(index))
     }
 
     /// Get an iterator over the values of the inner vector.
     #[track_caller]
-    fn iter(&self) -> ReadableValueIterator<'_, T, Self>
+    fn iter(&self) -> ReadableValueIterator<'_, Self>
     where
         Self: Sized,
     {
         ReadableValueIterator {
             index: 0,
             value: self,
-            phantom: std::marker::PhantomData,
         }
     }
 }
 
 /// An iterator over the values of a `Readable<Vec<T>>`.
-pub struct ReadableValueIterator<'a, T, R> {
+pub struct ReadableValueIterator<'a, R> {
     index: usize,
     value: &'a R,
-    phantom: std::marker::PhantomData<T>,
 }
 
-impl<'a, T: 'static, R: Readable<Vec<T>>> Iterator for ReadableValueIterator<'a, T, R> {
-    type Item = R::Ref<T>;
+impl<'a, T: 'static, R: Readable<Target = Vec<T>>> Iterator for ReadableValueIterator<'a, R> {
+    type Item = ReadableRef<R, T>;
 
     fn next(&mut self) -> Option<Self::Item> {
         let index = self.index;
@@ -157,12 +181,12 @@ impl<'a, T: 'static, R: Readable<Vec<T>>> Iterator for ReadableValueIterator<'a,
 impl<T, R> ReadableVecExt<T> for R
 where
     T: 'static,
-    R: Readable<Vec<T>>,
+    R: Readable<Target = Vec<T>>,
 {
 }
 
 /// An extension trait for Readable<Option<T>> that provides some convenience methods.
-pub trait ReadableOptionExt<T: 'static>: Readable<Option<T>> {
+pub trait ReadableOptionExt<T: 'static>: Readable<Target = Option<T>> {
     /// Unwraps the inner value and clones it.
     #[track_caller]
     fn unwrap(&self) -> T
@@ -174,14 +198,14 @@ pub trait ReadableOptionExt<T: 'static>: Readable<Option<T>> {
 
     /// Attempts to read the inner value of the Option.
     #[track_caller]
-    fn as_ref(&self) -> Option<Self::Ref<T>> {
-        Self::try_map_ref(self.read(), |v| v.as_ref())
+    fn as_ref(&self) -> Option<ReadableRef<Self, T>> {
+        <Self::Storage as AnyStorage>::try_map(self.read(), |v| v.as_ref())
     }
 }
 
 impl<T, R> ReadableOptionExt<T> for R
 where
     T: 'static,
-    R: Readable<Option<T>>,
+    R: Readable<Target = Option<T>>,
 {
 }

packages/signals/src/read_only_signal.rs

@@ -1,4 +1,4 @@
-use crate::{read::Readable, Signal, SignalData};
+use crate::{read::Readable, ReadableRef, Signal, SignalData};
 use std::ops::Deref;
 
 use dioxus_core::{prelude::IntoAttributeValue, ScopeId};
@@ -54,22 +54,12 @@ impl<T: 'static, S: Storage<SignalData<T>>> ReadOnlySignal<T, S> {
     }
 }
 
-impl<T, S: Storage<SignalData<T>>> Readable<T> for ReadOnlySignal<T, S> {
-    type Ref<R: ?Sized + 'static> = S::Ref<R>;
-
-    fn map_ref<I, U: ?Sized, F: FnOnce(&I) -> &U>(ref_: Self::Ref<I>, f: F) -> Self::Ref<U> {
-        S::map(ref_, f)
-    }
-
-    fn try_map_ref<I, U: ?Sized, F: FnOnce(&I) -> Option<&U>>(
-        ref_: Self::Ref<I>,
-        f: F,
-    ) -> Option<Self::Ref<U>> {
-        S::try_map(ref_, f)
-    }
+impl<T, S: Storage<SignalData<T>>> Readable for ReadOnlySignal<T, S> {
+    type Target = T;
+    type Storage = S;
 
     #[track_caller]
-    fn try_read(&self) -> Result<Self::Ref<T>, generational_box::BorrowError> {
+    fn try_read(&self) -> Result<ReadableRef<Self>, generational_box::BorrowError> {
         self.inner.try_read()
     }
 

packages/signals/src/signal.rs

@@ -1,6 +1,6 @@
 use crate::{
-    read::Readable, write::Writable, CopyValue, GlobalMemo, GlobalSignal, MappedSignal,
-    ReactiveContext, ReadOnlySignal,
+    read::Readable, write::Writable, CopyValue, GlobalMemo, GlobalSignal, ReactiveContext,
+    ReadOnlySignal, ReadableRef,
 };
 use dioxus_core::{
     prelude::{flush_sync, spawn, IntoAttributeValue},
@@ -187,33 +187,18 @@ impl<T: 'static, S: Storage<SignalData<T>>> Signal<T, S> {
         }
     }
 
-    /// Map the signal to a new type.
-    pub fn map<O>(self, f: impl Fn(&T) -> &O + 'static) -> MappedSignal<S::Ref<O>> {
-        MappedSignal::new(self, f)
-    }
-
     /// Get the generational id of the signal.
     pub fn id(&self) -> generational_box::GenerationalBoxId {
         self.inner.id()
     }
 }
 
-impl<T, S: Storage<SignalData<T>>> Readable<T> for Signal<T, S> {
-    type Ref<R: ?Sized + 'static> = S::Ref<R>;
-
-    fn map_ref<I, U: ?Sized, F: FnOnce(&I) -> &U>(ref_: Self::Ref<I>, f: F) -> Self::Ref<U> {
-        S::map(ref_, f)
-    }
-
-    fn try_map_ref<I, U: ?Sized, F: FnOnce(&I) -> Option<&U>>(
-        ref_: Self::Ref<I>,
-        f: F,
-    ) -> Option<Self::Ref<U>> {
-        S::try_map(ref_, f)
-    }
+impl<T, S: Storage<SignalData<T>>> Readable for Signal<T, S> {
+    type Target = T;
+    type Storage = S;
 
     #[track_caller]
-    fn try_read(&self) -> Result<S::Ref<T>, generational_box::BorrowError> {
+    fn try_read(&self) -> Result<ReadableRef<Self>, generational_box::BorrowError> {
         let inner = self.inner.try_read()?;
 
         let reactive_context = ReactiveContext::current();
@@ -225,23 +210,27 @@ impl<T, S: Storage<SignalData<T>>> Readable<T> for Signal<T, S> {
     /// Get the current value of the signal. **Unlike read, this will not subscribe the current scope to the signal which can cause parts of your UI to not update.**
     ///
     /// If the signal has been dropped, this will panic.
-    fn peek(&self) -> S::Ref<T> {
+    fn peek(&self) -> ReadableRef<Self> {
         let inner = self.inner.read();
         S::map(inner, |v| &v.value)
     }
 }
 
-impl<T: 'static, S: Storage<SignalData<T>>> Writable<T> for Signal<T, S> {
+impl<T: 'static, S: Storage<SignalData<T>>> Writable for Signal<T, S> {
     type Mut<R: ?Sized + 'static> = Write<R, S>;
 
-    fn map_mut<I, U: ?Sized + 'static, F: FnOnce(&mut I) -> &mut U>(
+    fn map_mut<I: ?Sized, U: ?Sized + 'static, F: FnOnce(&mut I) -> &mut U>(
         ref_: Self::Mut<I>,
         f: F,
     ) -> Self::Mut<U> {
         Write::map(ref_, f)
     }
 
-    fn try_map_mut<I: 'static, U: ?Sized + 'static, F: FnOnce(&mut I) -> Option<&mut U>>(
+    fn try_map_mut<
+        I: ?Sized + 'static,
+        U: ?Sized + 'static,
+        F: FnOnce(&mut I) -> Option<&mut U>,
+    >(
         ref_: Self::Mut<I>,
         f: F,
     ) -> Option<Self::Mut<U>> {

packages/signals/src/write.rs

@@ -1,40 +1,46 @@
 use std::ops::DerefMut;
+use std::ops::IndexMut;
 
 use crate::read::Readable;
 
 /// A trait for states that can be read from like [`crate::Signal`], or [`crate::GlobalSignal`]. You may choose to accept this trait as a parameter instead of the concrete type to allow for more flexibility in your API. For example, instead of creating two functions, one that accepts a [`crate::Signal`] and one that accepts a [`crate::GlobalSignal`], you can create one function that accepts a [`Writable`] type.
-pub trait Writable<T: 'static>: Readable<T> {
+pub trait Writable: Readable {
     /// The type of the reference.
-    type Mut<R: ?Sized + 'static>: DerefMut<Target = R>;
+    type Mut<R: ?Sized + 'static>: DerefMut<Target = R> + 'static;
 
     /// Map the reference to a new type.
-    fn map_mut<I, U: ?Sized, F: FnOnce(&mut I) -> &mut U>(ref_: Self::Mut<I>, f: F)
-        -> Self::Mut<U>;
+    fn map_mut<I: ?Sized, U: ?Sized, F: FnOnce(&mut I) -> &mut U>(
+        ref_: Self::Mut<I>,
+        f: F,
+    ) -> Self::Mut<U>;
 
     /// Try to map the reference to a new type.
-    fn try_map_mut<I, U: ?Sized, F: FnOnce(&mut I) -> Option<&mut U>>(
+    fn try_map_mut<I: ?Sized, U: ?Sized, F: FnOnce(&mut I) -> Option<&mut U>>(
         ref_: Self::Mut<I>,
         f: F,
     ) -> Option<Self::Mut<U>>;
 
     /// Get a mutable reference to the value. If the value has been dropped, this will panic.
     #[track_caller]
-    fn write(&mut self) -> Self::Mut<T> {
+    fn write(&mut self) -> Self::Mut<Self::Target> {
         self.try_write().unwrap()
     }
 
     /// Try to get a mutable reference to the value. If the value has been dropped, this will panic.
-    fn try_write(&self) -> Result<Self::Mut<T>, generational_box::BorrowMutError>;
+    fn try_write(&self) -> Result<Self::Mut<Self::Target>, generational_box::BorrowMutError>;
 
     /// Run a function with a mutable reference to the value. If the value has been dropped, this will panic.
     #[track_caller]
-    fn with_mut<O>(&mut self, f: impl FnOnce(&mut T) -> O) -> O {
+    fn with_mut<O>(&mut self, f: impl FnOnce(&mut Self::Target) -> O) -> O {
         f(&mut *self.write())
     }
 
     /// Set the value of the signal. This will trigger an update on all subscribers.
     #[track_caller]
-    fn set(&mut self, value: T) {
+    fn set(&mut self, value: Self::Target)
+    where
+        Self::Target: Sized,
+    {
         *self.write() = value;
     }
 
@@ -42,38 +48,41 @@ pub trait Writable<T: 'static>: Readable<T> {
     #[track_caller]
     fn toggle(&mut self)
     where
-        T: std::ops::Not<Output = T> + Clone,
+        Self::Target: std::ops::Not<Output = Self::Target> + Clone,
     {
         self.set(!self.cloned());
     }
 
     /// Index into the inner value and return a reference to the result.
     #[track_caller]
-    fn index_mut<I>(&mut self, index: I) -> Self::Mut<T::Output>
+    fn index_mut<I>(&mut self, index: I) -> Self::Mut<<Self::Target as std::ops::Index<I>>::Output>
     where
-        T: std::ops::IndexMut<I>,
+        Self::Target: std::ops::IndexMut<I>,
     {
         Self::map_mut(self.write(), |v| v.index_mut(index))
     }
 
     /// Takes the value out of the Signal, leaving a Default in its place.
     #[track_caller]
-    fn take(&mut self) -> T
+    fn take(&mut self) -> Self::Target
     where
-        T: Default,
+        Self::Target: Default,
     {
-        self.with_mut(|v| std::mem::take(v))
+        self.with_mut(std::mem::take)
     }
 
     /// Replace the value in the Signal, returning the old value.
     #[track_caller]
-    fn replace(&mut self, value: T) -> T {
+    fn replace(&mut self, value: Self::Target) -> Self::Target
+    where
+        Self::Target: Sized,
+    {
         self.with_mut(|v| std::mem::replace(v, value))
     }
 }
 
 /// An extension trait for Writable<Option<T>> that provides some convenience methods.
-pub trait WritableOptionExt<T: 'static>: Writable<Option<T>> {
+pub trait WritableOptionExt<T: 'static>: Writable<Target = Option<T>> {
     /// Gets the value out of the Option, or inserts the given value if the Option is empty.
     fn get_or_insert(&mut self, default: T) -> Self::Mut<T> {
         self.get_or_insert_with(|| default)
@@ -101,12 +110,12 @@ pub trait WritableOptionExt<T: 'static>: Writable<Option<T>> {
 impl<T, W> WritableOptionExt<T> for W
 where
     T: 'static,
-    W: Writable<Option<T>>,
+    W: Writable<Target = Option<T>>,
 {
 }
 
 /// An extension trait for Writable<Vec<T>> that provides some convenience methods.
-pub trait WritableVecExt<T: 'static>: Writable<Vec<T>> {
+pub trait WritableVecExt<T: 'static>: Writable<Target = Vec<T>> {
     /// Pushes a new value to the end of the vector.
     #[track_caller]
     fn push(&mut self, value: T) {
@@ -175,26 +184,24 @@ pub trait WritableVecExt<T: 'static>: Writable<Vec<T>> {
 
     /// Gets an iterator over the values of the vector.
     #[track_caller]
-    fn iter_mut(&self) -> WritableValueIterator<T, Self>
+    fn iter_mut(&self) -> WritableValueIterator<Self>
     where
         Self: Sized + Clone,
     {
         WritableValueIterator {
             index: 0,
             value: self.clone(),
-            phantom: std::marker::PhantomData,
         }
     }
 }
 
 /// An iterator over the values of a `Writable<Vec<T>>`.
-pub struct WritableValueIterator<T, R> {
+pub struct WritableValueIterator<R> {
     index: usize,
     value: R,
-    phantom: std::marker::PhantomData<T>,
 }
 
-impl<T: 'static, R: Writable<Vec<T>>> Iterator for WritableValueIterator<T, R> {
+impl<T: 'static, R: Writable<Target = Vec<T>>> Iterator for WritableValueIterator<R> {
     type Item = R::Mut<T>;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -207,6 +214,6 @@ impl<T: 'static, R: Writable<Vec<T>>> Iterator for WritableValueIterator<T, R> {
 impl<T, W> WritableVecExt<T> for W
 where
     T: 'static,
-    W: Writable<Vec<T>>,
+    W: Writable<Target = Vec<T>>,
 {
 }