packages/example/src/routes/tests.tsx

@@ -10,6 +10,13 @@ export const Route = createFileRoute("/tests")({
 })
 
 function RouteComponent() {
+    const deepRef = R.useRef({ value: "poulet" })
+    const deepValueRef = R.useSubRefFromGetSet(
+        deepRef,
+        b => b.value,
+        (b, a) => ({ ...b, value: a }),
+    )
+
     // const value = R.useMemoScoped(Effect.addFinalizer(() => Console.log("cleanup")).pipe(
     //     Effect.andThen(makeUuid4),
     //     Effect.provide(GetRandomValues.CryptoRandom),
@@ -32,7 +39,8 @@ function RouteComponent() {
 
     const generateUuid = R.useCallbackSync(() => makeUuid4.pipe(
         Effect.provide(GetRandomValues.CryptoRandom),
-        Effect.flatMap(v => Ref.set(uuidRef, v)),
+        Effect.tap(v => Ref.set(uuidRef, v)),
+        Effect.tap(v => Ref.set(deepValueRef, v)),
     ), [])
 
 
@@ -42,6 +50,10 @@ function RouteComponent() {
                 {(uuid, anotherRef) => <Text>{uuid} / {anotherRef}</Text>}
             </R.SubscribeRefs>
 
+            <R.SubscribeRefs refs={[deepRef, deepValueRef]}>
+                {(deep, deepValue) => <Text>{JSON.stringify(deep)} / {deepValue}</Text>}
+            </R.SubscribeRefs>
+
             <Button onClick={() => logValue("test")}>Log value</Button>
             <Button onClick={() => generateUuid()}>Generate UUID</Button>
         </Flex>

packages/extension-lazyref/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@reffuse/extension-lazyref",
-  "version": "0.1.3",
+  "version": "0.1.4",
   "type": "module",
   "files": [
     "./README.md",
@@ -37,6 +37,6 @@
     "@types/react": "^19.0.0",
     "effect": "^3.13.0",
     "react": "^19.0.0",
-    "reffuse": "^0.1.7"
+    "reffuse": "^0.1.8"
   }
 }

packages/extension-lazyref/src/index.ts

@@ -1,7 +1,8 @@
 import * as LazyRef from "@typed/lazy-ref"
 import { Effect, pipe, Stream } from "effect"
 import * as React from "react"
-import { ReffuseExtension, type ReffuseNamespace, SetStateAction } from "reffuse"
+import { ReffuseExtension, type ReffuseNamespace } from "reffuse"
+import { SetStateAction } from "reffuse/types"
 
 
 export const LazyRefExtension = ReffuseExtension.make(() => ({

packages/reffuse/package.json

@@ -1,6 +1,6 @@
 {
   "name": "reffuse",
-  "version": "0.1.7",
+  "version": "0.1.8",
   "type": "module",
   "files": [
     "./README.md",
@@ -16,6 +16,10 @@
       "types": "./dist/index.d.ts",
       "default": "./dist/index.js"
     },
+    "./types": {
+      "types": "./dist/types/index.d.ts",
+      "default": "./dist/types/index.js"
+    },
     "./*": {
       "types": "./dist/*.d.ts",
       "default": "./dist/*.js"

packages/reffuse/src/Reffuse.ts

@@ -1,7 +1,7 @@
 import type * as ReffuseContext from "./ReffuseContext.js"
 import type * as ReffuseExtension from "./ReffuseExtension.js"
 import * as ReffuseNamespace from "./ReffuseNamespace.js"
-import type { Merge, StaticType } from "./types.js"
+import type { Merge, StaticType } from "./utils.js"
 
 
 export class Reffuse extends ReffuseNamespace.makeClass() {}

packages/reffuse/src/ReffuseNamespace.ts

@@ -2,7 +2,7 @@ import { type Context, Effect, ExecutionStrategy, Exit, type Fiber, type Layer,
 import * as React from "react"
 import * as ReffuseContext from "./ReffuseContext.js"
 import * as ReffuseRuntime from "./ReffuseRuntime.js"
-import * as SetStateAction from "./SetStateAction.js"
+import { SetStateAction, SubscriptionSubRef } from "./types/index.js"
 
 
 export interface RenderOptions {
@@ -384,6 +384,18 @@ export abstract class ReffuseNamespace<R> {
         )
     }
 
+    useSubRefFromGetSet<A, B, R>(
+        this: ReffuseNamespace<R>,
+        parent: SubscriptionRef.SubscriptionRef<B>,
+        getter: (parentValue: B) => A,
+        setter: (parentValue: B, value: A) => B,
+    ): SubscriptionSubRef.SubscriptionSubRef<A, B> {
+        return React.useMemo(
+            () => SubscriptionSubRef.makeFromGetSet(parent, getter, setter),
+            [parent],
+        )
+    }
+
     useSubscribeRefs<
         const Refs extends readonly SubscriptionRef.SubscriptionRef<any>[],
         R,

packages/reffuse/src/index.ts

@@ -3,4 +3,3 @@ export * as ReffuseContext from "./ReffuseContext.js"
 export * as ReffuseExtension from "./ReffuseExtension.js"
 export * as ReffuseNamespace from "./ReffuseNamespace.js"
 export * as ReffuseRuntime from "./ReffuseRuntime.js"
-export * as SetStateAction from "./SetStateAction.js"

packages/reffuse/src/types/SubscriptionSubRef.ts

@@ -0,0 +1,77 @@
+import { Effect, Effectable, Readable, Ref, Stream, Subscribable, SubscriptionRef, SynchronizedRef, type Types } from "effect"
+
+
+export const SubscriptionSubRefTypeId: unique symbol = Symbol.for("reffuse/types/SubscriptionSubRef")
+
+export interface SubscriptionSubRef<in out A, in out B> extends SubscriptionSubRef.Variance<A, B>, SubscriptionRef.SubscriptionRef<A> {
+    readonly parent: SubscriptionRef.SubscriptionRef<B>
+}
+
+export declare namespace SubscriptionSubRef {
+    export interface Variance<in out A, in out B> {
+        readonly [SubscriptionSubRefTypeId]: {
+            readonly _A: Types.Invariant<A>
+            readonly _B: Types.Invariant<B>
+        }
+    }
+}
+
+
+const refVariance = { _A: (_: any) => _ }
+const synchronizedRefVariance = { _A: (_: any) => _ }
+const subscriptionRefVariance = { _A: (_: any) => _ }
+const subscriptionSubRefVariance = { _A: (_: any) => _, _B: (_: any) => _ }
+
+class SubscriptionSubRefImpl<in out A, in out B> extends Effectable.Class<A> implements SubscriptionSubRef<A, B> {
+    readonly [Readable.TypeId]: Readable.TypeId = Readable.TypeId
+    readonly [Subscribable.TypeId]: Subscribable.TypeId = Subscribable.TypeId
+    readonly [Ref.RefTypeId] = refVariance
+    readonly [SynchronizedRef.SynchronizedRefTypeId] = synchronizedRefVariance
+    readonly [SubscriptionRef.SubscriptionRefTypeId] = subscriptionRefVariance
+    readonly [SubscriptionSubRefTypeId] = subscriptionSubRefVariance
+
+    readonly get: Effect.Effect<A>
+
+    constructor(
+        readonly parent: SubscriptionRef.SubscriptionRef<B>,
+        readonly getter: (parentValue: B) => A,
+        readonly setter: (parentValue: B, value: A) => B,
+    ) {
+        super()
+        this.get = Ref.get(this.parent).pipe(Effect.map(this.getter))
+    }
+
+    commit() {
+        return this.get
+    }
+
+    get changes(): Stream.Stream<A> {
+        return this.get.pipe(
+            Effect.map(a => this.parent.changes.pipe(
+                Stream.map(this.getter),
+                s => Stream.concat(Stream.make(a), s),
+            )),
+            Stream.unwrap,
+        )
+    }
+
+    modify<C>(f: (a: A) => readonly [C, A]): Effect.Effect<C> {
+        return this.modifyEffect(a => Effect.succeed(f(a)))
+    }
+
+    modifyEffect<C, E, R>(f: (a: A) => Effect.Effect<readonly [C, A], E, R>): Effect.Effect<C, E, R> {
+        return Effect.Do.pipe(
+            Effect.bind("b", () => Ref.get(this.parent)),
+            Effect.bind("ca", ({ b }) => f(this.getter(b))),
+            Effect.tap(({ b, ca: [, a] }) => Ref.set(this.parent, this.setter(b, a))),
+            Effect.map(({ ca: [c] }) => c),
+        )
+    }
+}
+
+
+export const makeFromGetSet = <A, B>(
+    parent: SubscriptionRef.SubscriptionRef<B>,
+    getter: (parentValue: B) => A,
+    setter: (parentValue: B, value: A) => B,
+): SubscriptionSubRef<A, B> => new SubscriptionSubRefImpl(parent, getter, setter)

packages/reffuse/src/types/index.ts

@@ -0,0 +1,2 @@
+export * as SetStateAction from "./SetStateAction.js"
+export * as SubscriptionSubRef from "./SubscriptionSubRef.js"