Mapped type for combineReducers in index.d.ts

index.d.ts

@@ -43,13 +43,13 @@ export interface Action {
  *
  * @template S State object type.
  */
-export type Reducer<S> = <A extends Action>(state: S, action: A) => S;
+export type Reducer<S> = <A extends Action>(state: S | undefined, action: A) => S;
 
 /**
  * Object whose values correspond to different reducer functions.
  */
-export interface ReducersMapObject {
-  [key: string]: Reducer<any>;
+export type ReducersMapObject<S> = {
+  [K in keyof S]: Reducer<S[K]>;
 }
 
 /**
@@ -70,7 +70,7 @@ export interface ReducersMapObject {
  * @returns A reducer function that invokes every reducer inside the passed
  *   object, and builds a state object with the same shape.
  */
-export function combineReducers<S>(reducers: ReducersMapObject): Reducer<S>;
+export function combineReducers<S>(reducers: ReducersMapObject<S>): Reducer<S>;
 
 
 /* store */

package.json

@@ -108,8 +108,8 @@
     "jest": "^15.1.1",
     "rimraf": "^2.3.4",
     "rxjs": "^5.0.0-beta.6",
-    "typescript": "^1.8.0",
-    "typescript-definition-tester": "0.0.4",
+    "typescript": "^2.1.0",
+    "typescript-definition-tester": "0.0.5",
     "webpack": "^1.9.6"
   },
   "npmName": "redux",

test/typescript.spec.js

@@ -6,6 +6,9 @@ describe('TypeScript definitions', function () {
     tt.compileDirectory(
       __dirname + '/typescript',
       fileName => fileName.match(/\.ts$/),
+      {
+        strictNullChecks: true
+      },
       () => done()
     )
   })

test/typescript/actionCreators.ts

@@ -1,7 +1,7 @@
 import {
   ActionCreator, Action, Dispatch,
   bindActionCreators, ActionCreatorsMapObject
-} from "../../index.d.ts";
+} from "../../";
 
 
 interface AddTodoAction extends Action {

test/typescript/actions.ts

@@ -1,4 +1,4 @@
-import {Action as ReduxAction} from "../../index.d.ts";
+import {Action as ReduxAction} from "../../";
 
 
 namespace FSA {

test/typescript/compose.ts

@@ -1,4 +1,4 @@
-import {compose} from "../../index.d.ts";
+import {compose} from "../../";
 
 // copied from DefinitelyTyped/compose-function
 

test/typescript/dispatch.ts

@@ -1,12 +1,12 @@
-import {Dispatch, Action} from "../../index.d.ts";
+import {Dispatch, Action} from "../../";
 
 
 declare const dispatch: Dispatch<any>;
 
 const dispatchResult: Action = dispatch({type: 'TYPE'});
 
 // thunk
-declare module "../../index.d.ts" {
+declare module "../../" {
     export interface Dispatch<S> {
         <R>(asyncAction: (dispatch: Dispatch<S>, getState: () => S) => R): R;
     }

test/typescript/middleware.ts

@@ -1,9 +1,9 @@
 import {
   Middleware, MiddlewareAPI,
   applyMiddleware, createStore, Dispatch, Reducer, Action
-} from "../../index.d.ts";
+} from "../../";
 
-declare module "../../index.d.ts" {
+declare module "../../" {
     export interface Dispatch<S> {
         <R>(asyncAction: (dispatch: Dispatch<S>, getState: () => S) => R): R;
     }

test/typescript/reducers.ts

@@ -1,7 +1,7 @@
 import {
   Reducer, Action, combineReducers,
   ReducersMapObject
-} from "../../index.d.ts";
+} from "../../";
 
 
 type TodosState = string[];
@@ -47,8 +47,7 @@ type RootState = {
   counter: CounterState;
 }
 
-
-const rootReducer: Reducer<RootState> = combineReducers<RootState>({
+const rootReducer: Reducer<RootState> = combineReducers({
   todos: todosReducer,
   counter: counterReducer,
 })

test/typescript/store.ts

@@ -1,7 +1,7 @@
 import {
   Store, createStore, Reducer, Action, StoreEnhancer, GenericStoreEnhancer,
   StoreCreator, StoreEnhancerStoreCreator, Unsubscribe
-} from "../../index.d.ts";
+} from "../../";
 
 
 type State = {