document the mapping behavior of a '*' subdux

README.md

@@ -123,6 +123,59 @@ const {
 } = updux;
 ```
 
+## Mapping a mutation to all values of a state
+
+Say you have a `todos` state that is an array of `todo` sub-states. It's easy
+enough to have the main reducer maps away all items to the sub-reducer:
+
+```
+const todo = new Updux({
+    mutations: {
+        review: () => u({ reviewed: true}),
+        done: () => u({done: true}),
+    },
+});
+
+const todos = new Updux({ initial: [] });
+
+todos.addMutation( 
+    todo.actions.review, 
+    (_,action) => state => state.map( todo.upreducer(action) )  
+);
+todos.addMutation(
+    todo.actions.done, 
+    (id,action) => u.map(u.if(u.is('id',id), todo.upreducer(action))),
+);
+
+```
+
+But `updeep` can iterate through all the items of an array (or the values of
+an object) via the special key `*`. So the todos updux above could also be
+written:
+
+```
+const todo = new Updux({
+    mutations: {
+        review: () => u({ reviewed: true}),
+        done: () => u({done: true}),
+    },
+});
+
+const todos = new Updux({
+    subduxes: { '*': todo },
+});
+
+todos.addMutation(
+    todo.actions.done, 
+    (id,action) => u.map(u.if(u.is('id',id), todo.upreducer(action))), 
+    true
+);
+```
+
+The advantages being that the actions/mutations/effects of the subdux will be
+imported by the root updux as usual, and all actions that aren't being 
+overridden by a sink mutation will trickle down automatically.
+
 ## Usage with Immer
 
 While Updux was created with Updeep in mind, it also plays very

src/buildMutations/index.ts

@@ -50,8 +50,6 @@ function buildMutations(
   nonGlobby.forEach(([slice, {mutations = {}, reducer = {}}]:any[]) => {
     Object.entries(mutations).forEach(([type, mutation]) => {
       const localized = (payload = null, action :Action) => {
-          console.log(slice);
-
         return u.updateIn(slice)((mutation as Mutation)(payload, action));
       }
 

src/mappedUpdux.test.ts

@@ -0,0 +1,29 @@
+import Updux from './updux';
+import u from 'updeep';
+
+const todo = new Updux({
+    mutations: {
+        review: () => u({ reviewed: true}),
+        done: () => u({done: true}),
+    },
+});
+
+const todos = new Updux({
+    subduxes: { '*': todo },
+});
+
+todos.addMutation(
+    todo.actions.done, (id,action) => u.map(u.if(u.is('id',id), todo.upreducer(action))), true
+);
+
+test( '* for mapping works', () => {
+    const reducer = todos.reducer;
+    let state = [ { id: 0 }, {id: 1 } ];
+    state = reducer( state, todos.actions.review() );
+    state = reducer( state, todos.actions.done(1) );
+
+    expect(state).toEqual([
+        { id: 0, reviewed: true },
+        { id: 1, reviewed: true, done: true },
+    ]);
+});