Annotate composeMiddleware.js

Author: acdlite

src/utils/composeMiddleware.js

@@ -1,3 +1,9 @@
-export default function compose(...middlewares) {
-  return middlewares.reduceRight((composed, m) => m(composed));
+/* @flow */
+
+import { Middleware, Dispatch } from '../types';
+
+export default function compose(...middlewares: Middleware[]): Middleware {
+  return middlewares.reduceRight(
+    (composed: Middleware | Dispatch, m: Middleware | Dispatch) => m(composed)
+  );
 }