add replaceReducer config

src/StoreClass.ts

@@ -4,13 +4,15 @@ import { StoreInterface } from './StoreInterface'
 import { StoreState } from './State'
 import { MessageHandlers } from './MessageHandler'
 import { DevToolsOptions } from './DevTools'
+import { StoreReducer } from './Reducer'
 
 // Options passed to createStoreClass()
 export interface CreateStoreClassOptions<T extends StoreInterface> {
   initialState: StoreState<T>
   messageHandlers: MessageHandlers<T>
   middleware?: Middleware<T> | Middleware<T>[]
   devToolsOptions?: DevToolsOptions<T>
+  replaceReducer?: (rootReducer: StoreReducer<T>) => StoreReducer<T>
 }
 
 // Defines Shape and Behaviour of a Store.

src/StoreInstance.ts

@@ -51,7 +51,10 @@ export function createStoreInstance<T extends StoreInterface>(
 
   // The Reducer of this store needs access to the dispatch, as individual messageHandlers might want to
   // dispatch additional messages.
-  const reducer = createReducer(options, storeInstance)
+  let reducer = createReducer(options, storeInstance)
+  if (options.replaceReducer) {
+    reducer = options.replaceReducer(reducer)
+  }
 
   // Build up the chain of middlewares
   const executeMiddleware = createExecuteMiddleware(