Convert types dispatcher to TS

Summary: Convert file to TS

Reviewed By: passy

Differential Revision: D16687880

fbshipit-source-id: d3d8712fa4298f8124717ae98239ed63d3282b12

src/dispatcher/index.js

@@ -17,7 +17,7 @@ import user from './user.tsx';
 
 import type {Logger} from '../fb-interfaces/Logger.js';
 import type {Store} from '../reducers/index.tsx';
-import type {Dispatcher} from './types';
+import type {Dispatcher} from './types.tsx';
 
 export default function(store: Store, logger: Logger): () => Promise<void> {
   const dispatchers: Array<Dispatcher> = [

src/dispatcher/types.js

@@ -1,10 +0,0 @@
-/**
- * Copyright 2018-present Facebook.
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- * @format
- */
-import type {Store} from '../reducers/index.tsx';
-import type {Logger} from '../fb-interfaces/Logger';
-
-export type Dispatcher = (store: Store, logger: Logger) => ?() => Promise<void>;

src/dispatcher/types.tsx

@@ -0,0 +1,13 @@
+/**
+ * Copyright 2018-present Facebook.
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ * @format
+ */
+import {Store} from '../reducers/index.js';
+import {Logger} from '../fb-interfaces/Logger';
+
+export type Dispatcher = (
+  store: Store,
+  logger: Logger,
+) => (() => Promise<void>) | null;