Conditionally import immutable and use either isImmutable or isIterable

demo/server/index.js

@@ -84,7 +84,7 @@ app.get('/*', (req, res) => {
   const initialState = {};
   const initialStateJSON = encode(JSON.stringify(initialState));
   // const initialState = Map();
-  // const initialStateJSON = JSON.stringify(initialState.toJSON()),
+  // const initialStateJSON = JSON.stringify(initialState.toJSON());
 
   const router = routerForExpress({ routes, request: req });
   const store = createStore(

src/immutable/components/props-to-js.js

@@ -2,7 +2,7 @@
 import type { Component } from 'react';
 
 import React from 'react';
-import { Iterable } from 'immutable';
+import { isImmutable } from '../util/immutable';
 
 type Props = {
   [key: string]: any
@@ -12,7 +12,7 @@ export default (WrappedComponent: Class<Component<*, *, *>>) =>
   (wrappedProps: Props) => {
     const propsJS = Object.keys(wrappedProps).reduce((props, key) => ({
       ...props,
-      [key]: Iterable.isIterable(wrappedProps[key]) ? wrappedProps[key].toJS() : wrappedProps[key]
+      [key]: isImmutable(wrappedProps[key]) ? wrappedProps[key].toJS() : wrappedProps[key]
     }), {});
 
     return (<WrappedComponent {...propsJS} />);

src/immutable/reducer.js

@@ -5,7 +5,7 @@ import type { Map as MapType } from 'immutable';
 import type { ReducerArgs } from '../reducer';
 import type { Location, LocationAction } from '../types';
 
-import { List, Map, fromJS } from 'immutable';
+import { List, Map, fromJS } from './util/immutable';
 
 import {
   LOCATION_CHANGED,

src/immutable/util/immutable.js

@@ -0,0 +1,31 @@
+// @flow
+/* eslint-disable import/no-mutable-exports, no-empty */
+const throwError = (...args) => {
+  throw new Error(
+    `immutable.js was not imported. Make sure you have it installed. Was called with ${args}.`
+  );
+};
+
+let immutable;
+let Map = throwError;
+let List = throwError;
+let fromJS = throwError;
+let isImmutable = throwError;
+
+try {
+  immutable = require('immutable');
+  Map = immutable.Map;
+  List = immutable.List;
+  fromJS = immutable.fromJS;
+  // To account for immutable versions 3.8.x -> 4.x.x
+  isImmutable = immutable.isImmutable ? immutable.isImmutable : immutable.Iterable.isIterable;
+} catch (e) {}
+
+export {
+  Map,
+  List,
+  fromJS,
+  isImmutable
+};
+
+export default immutable;

src/index.js

@@ -26,8 +26,8 @@ import routerForExpress from './environment/express-router';
 import routerForHapi from './environment/hapi-router';
 
 import immutableRouterForBrowser from './immutable/environment/browser-router';
-import immutableRouterForHash from './immutable/environment/hash-router';
 import immutableRouterForExpress from './immutable/environment/express-router';
+import immutableRouterForHash from './immutable/environment/hash-router';
 import immutableRouterForHapi from './immutable/environment/hapi-router';
 
 import { Link, PersistentQueryLink } from './components/link';