store runs produce

Author: jbolda

src/store/schema.ts

@@ -249,16 +249,9 @@ export function createSchema<const O extends FxMap = FxMap>(
         Array.isArray(ctx.updater) ? ctx.updater : [ctx.updater]
       ) as StoreUpdater<SliceFromSchema<O>>[];
 
-      const [nextState, patches, _] = produceWithPatches<SliceFromSchema<O>>(
-        store.getState(),
-        (draft: Draft<SliceFromSchema<O>>) => {
-          upds.forEach((updater) => updater(draft));
-        },
-      );
+      const [_nextState, patches, _inversePatches] = store.setState(upds);
       ctx.patches = patches;
 
-      store.setState(nextState);
-
       yield* next();
     },
   });

src/store/store.ts

@@ -5,7 +5,7 @@ import {
   createScope,
   createSignal,
 } from "effection";
-import { produce } from "immer";
+import { Draft, produce, produceWithPatches } from "immer";
 import { ActionContext, emit } from "../action.js";
 import { parallel } from "../fx/parallel.js";
 import type { AnyAction } from "../types.js";
@@ -17,6 +17,7 @@ import type {
   FxStore,
   Listener,
   SliceFromSchema,
+  StoreUpdater,
 } from "./types.js";
 const stubMsg = "This is merely a stub, not implemented";
 
@@ -148,13 +149,16 @@ export function createStore<O extends FxMap>({
     return state;
   }
 
-  function setState(newState: SliceFromSchema<O>) {
-    // enables merging multiple states from
-    // different schemas without overwriting the whole state
-    // TODO but this means double produce on the default single schema case
-    state = produce(state, (draft) => {
-      Object.assign(draft, newState);
-    });
+  function setState(upds: StoreUpdater<SliceFromSchema<O>>[]) {
+    const nextState = produceWithPatches(
+      state,
+      (draft: Draft<SliceFromSchema<O>>) => {
+        upds.forEach((updater) => updater(draft));
+      },
+    );
+
+    state = nextState[0];
+    return nextState;
   }
 
   function getInitialState() {

src/store/types.ts

@@ -1,5 +1,5 @@
 import type { Operation, Scope } from "effection";
-import type { Draft, Immutable, Patch } from "immer";
+import type { Draft, Immutable, Patch, produceWithPatches } from "immer";
 import type { BaseCtx } from "../compose.js";
 import type { AnyAction, AnyState } from "../types.js";
 import type { createRun } from "./run.js";
@@ -136,7 +136,9 @@ export interface FxStore<O extends FxMap> {
   getScope: () => Scope;
   // part of redux store API
   getState: () => SliceFromSchema<O>;
-  setState: (s: SliceFromSchema<O>) => void;
+  setState: (
+    upds: StoreUpdater<SliceFromSchema<O>>[],
+  ) => ReturnType<typeof produceWithPatches>;
   // part of redux store API
   subscribe: (fn: Listener) => () => void;
   // the default schema for this store