diff --git a/.gitignore b/.gitignore
index c05203a..03995cf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 node_modules/
 tsconfig.tsbuildinfo
+**/*.orig
diff --git a/docs/_sidebar.md b/docs/_sidebar.md
index 67ee16e..dfdd5c5 100644
--- a/docs/_sidebar.md
+++ b/docs/_sidebar.md
@@ -1,5 +1,6 @@
 <!-- docs/_sidebar.md -->
 
 * [Home](/)
+* [Concepts](concepts.md)
 * API Reference
     * [Updux](updux.md)
diff --git a/docs/concepts.md b/docs/concepts.md
new file mode 100644
index 0000000..65cbbc6
--- /dev/null
+++ b/docs/concepts.md
@@ -0,0 +1,30 @@
+ # Updux concepts
+
+## effects
+
+Updux effects are a superset of redux middleware. I kept that format, and the
+use of `next` mostly because I wanted to give myself a way to alter 
+actions before they hit the reducer, something that `redux-saga` and 
+`rematch` don't allow.
+
+An effect has the signature
+
+```js
+const effect = ({ getState, dispatch, getRootState, selectors}) 
+                => next => action => { ... }
+```
+
+The first argument is like the usual redux middlewareApi, except
+for the availability of selectors and of the root updux's state. 
+
+Also, the function `dispatch` is augmented to be able to be called 
+with the allowed actions as props. For example, assuming that the action
+`complete_todo` has been declared somewhere, then it's possible to do:
+
+```js
+updux.addEffect( 'todo_bankrupcy',
+    ({ getState, dispatch }) => next => action => {
+        getState.forEach( todo => dispatch.complete_todo( todo.id ) );
+    }
+)
+```
diff --git a/docs/updux.md b/docs/updux.md
index d95ba2c..debb225 100644
--- a/docs/updux.md
+++ b/docs/updux.md
@@ -36,6 +36,23 @@ const { actions } = updux({
 
 actions.foo({ x: 1, y: 2 }); // => { type: foo, payload: { x:1, y:2  } }
 actions.bar(1,2);            // => { type: bar, payload: { x:1, y:2  } }
+
+
+#### selectors
+
+Dictionary of selectors for the current updux. The updux also
+inherit its dubduxes' selectors. 
+
+The selectors are available via the class' getter and, for 
+middlewares, the middlewareApi.
+
+```js
+const todoUpdux = new Updux({
+    selectors: {
+        done: state => state.filter( ({done}) => done ),
+        byId: state => targetId => state.find( ({id}) => id === targetId ),
+    }
+}
 ```
 
 #### mutations
@@ -332,3 +349,11 @@ baz();         // => { type: 'baz', payload: undefined }
 
 ```
 
+### selectors
+
+Returns a dictionary of the 
+updux's selectors. Subduxes' selectors 
+are included as well (with the mapping to the sub-state already 
+taken care of you).
+
+
diff --git a/src/buildMiddleware/index.ts b/src/buildMiddleware/index.ts
index 0b1d198..8421869 100644
--- a/src/buildMiddleware/index.ts
+++ b/src/buildMiddleware/index.ts
@@ -10,6 +10,7 @@ import {
   UpduxMiddlewareAPI,
   EffectEntry
 } from "../types";
+import Updux from "..";
 
 const MiddlewareFor = (
   type: any,
@@ -23,12 +24,13 @@ const MiddlewareFor = (
 
 type Next = (action: Action) => any;
 
-function sliceMw(slice: string, mw: Middleware): Middleware {
+function sliceMw(slice: string, mw: Middleware, updux: Updux): Middleware {
   return api => {
     const getSliceState =
       slice.length > 0 ? () => fp.get(slice, api.getState()) : api.getState;
     const getRootState = (api as any).getRootState || api.getState;
-    return mw({ ...api, getState: getSliceState, getRootState } as any);
+    return mw({ ...api, getState: getSliceState, getRootState,
+        selectors: updux.selectors } as any);
   };
 }
 
@@ -37,11 +39,11 @@ function buildMiddleware<S = any>(
   actions: Dictionary<ActionCreator> = {}
 ): UpduxMiddleware<S> {
   let mws = middlewareEntries
-    .map(([slice, actionType, mw, isGen]: any) =>
-      isGen ? [slice, actionType, mw()] : [slice, actionType, mw]
+    .map(([updux, slice, actionType, mw, isGen]: any) =>
+      isGen ? [updux, slice, actionType, mw()] : [updux, slice, actionType, mw]
     )
-    .map(([slice, actionType, mw]) =>
-      MiddlewareFor(actionType, sliceMw(slice, mw))
+    .map(([updux, slice, actionType, mw]) =>
+      MiddlewareFor(actionType, sliceMw(slice, mw, updux))
     );
 
   return (api: UpduxMiddlewareAPI<S>) => {
diff --git a/src/buildSelectors/index.ts b/src/buildSelectors/index.ts
new file mode 100644
index 0000000..217202b
--- /dev/null
+++ b/src/buildSelectors/index.ts
@@ -0,0 +1,26 @@
+import fp from 'lodash/fp';
+import Updux from '..';
+import { Dictionary, Selector } from '../types';
+
+function subSelectors([slice, subdux]: [string, Updux]): [string, Selector][] {
+    const selectors = subdux.selectors;
+    if (!selectors) return [];
+
+    return Object.entries(
+        fp.mapValues(selector => (state: any) =>
+            (selector as any)(state[slice])
+        )(selectors)
+    );
+}
+
+export default function buildSelectors(
+    localSelectors: Dictionary<Selector> = {},
+    subduxes: Dictionary<Updux> = {}
+) {
+    return Object.fromEntries(
+        [
+            Object.entries(subduxes).flatMap(subSelectors),
+            Object.entries(localSelectors),
+        ].flat()
+    );
+}
diff --git a/src/middleware.test.ts b/src/middleware.test.ts
index 54d02a9..e3a0a1c 100644
--- a/src/middleware.test.ts
+++ b/src/middleware.test.ts
@@ -1,228 +1,277 @@
-import Updux, { actionCreator } from ".";
-import u from "updeep";
+import Updux, { actionCreator } from '.';
+import u from 'updeep';
+import mwUpdux from './middleware_aux';
 
-test("simple effect", () => {
-  const tracer = jest.fn();
+test('simple effect', () => {
+    const tracer = jest.fn();
 
-  const store = new Updux({
-    effects: {
-      foo: (api: any) => (next: any) => (action: any) => {
-        tracer();
-        next(action);
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch({ type: "bar" });
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch.foo();
-
-  expect(tracer).toHaveBeenCalled();
-});
-
-test("effect and sub-effect", () => {
-  const tracer = jest.fn();
-
-  const tracerEffect = (signature: string) => (api: any) => (next: any) => (
-    action: any
-  ) => {
-    tracer(signature);
-    next(action);
-  };
-
-  const store = new Updux({
-    effects: {
-      foo: tracerEffect("root")
-    },
-    subduxes: {
-      zzz: {
+    const store = new Updux({
         effects: {
-          foo: tracerEffect("child")
-        }
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch({ type: "bar" });
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch.foo();
-
-  expect(tracer).toHaveBeenNthCalledWith(1, "root");
-  expect(tracer).toHaveBeenNthCalledWith(2, "child");
-});
-
-test('"*" effect', () => {
-  const tracer = jest.fn();
-
-  const store = new Updux({
-    effects: {
-      "*": api => next => action => {
-        tracer();
-        next(action);
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch({ type: "bar" });
-
-  expect(tracer).toHaveBeenCalled();
-});
-
-test("async effect", async () => {
-  function timeout(ms: number) {
-    return new Promise(resolve => setTimeout(resolve, ms));
-  }
-
-  const tracer = jest.fn();
-
-  const store = new Updux({
-    effects: {
-      foo: api => next => async action => {
-        next(action);
-        await timeout(1000);
-        tracer();
-      }
-    }
-  }).createStore();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  store.dispatch.foo();
-
-  expect(tracer).not.toHaveBeenCalled();
-
-  await timeout(1000);
-
-  expect(tracer).toHaveBeenCalled();
-});
-
-test("getState is local", () => {
-  let childState;
-  let rootState;
-  let rootFromChild;
-
-  const child = new Updux({
-    initial: { alpha: 12 },
-    effects: {
-      doIt: ({ getState, getRootState }) => next => action => {
-        childState = getState();
-        rootFromChild = getRootState();
-        next(action);
-      }
-    }
-  });
-
-  const root = new Updux({
-    initial: { beta: 24 },
-    subduxes: { child },
-    effects: {
-      doIt: ({ getState }) => next => action => {
-        rootState = getState();
-        next(action);
-      }
-    }
-  });
-
-  const store = root.createStore();
-  store.dispatch.doIt();
-
-  expect(rootState).toEqual({ beta: 24, child: { alpha: 12 } });
-  expect(rootFromChild).toEqual({ beta: 24, child: { alpha: 12 } });
-  expect(childState).toEqual({ alpha: 12 });
-});
-
-test("middleware as map", () => {
-  let childState;
-  let rootState;
-  let rootFromChild;
-
-  const doIt = actionCreator("doIt");
-
-  const child = new Updux({
-    initial: "",
-    effects: [
-      [
-        doIt,
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "Child" }, action) as any);
-        }
-      ]
-    ]
-  });
-
-  const root = new Updux({
-    initial: { message: "" },
-    subduxes: { child },
-    effects: [
-      [
-        "^",
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "Pre" }, action) as any);
-        }
-      ],
-      [
-        doIt,
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "Root" }, action) as any);
-        }
-      ],
-      [
-        "*",
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "After" }, action) as any);
-        }
-      ],
-      [
-        "$",
-        () => next => action => {
-          next(u({ payload: (p: string) => p + "End" }, action) as any);
-        }
-      ]
-    ],
-    mutations: [[doIt, (message: any) => () => ({ message })]]
-  });
-
-  const store = root.createStore();
-  store.dispatch.doIt("");
-
-  expect(store.getState()).toEqual({ message: "PreRootAfterChildEnd" });
-});
-
-test("generator", () => {
-  const updux = new Updux({
-    initial: 0,
-    mutations: [["doIt", payload => () => payload]],
-    effects: [
-      [
-        "doIt",
-        () => {
-          let i = 0;
-          return () => (next: any) => (action: any) =>
-            next({ ...action, payload: ++i });
+            foo: (api: any) => (next: any) => (action: any) => {
+                tracer();
+                next(action);
+            },
         },
-        true
-      ]
-    ]
-  });
+    }).createStore();
 
-  const store1 = updux.createStore();
-  store1.dispatch.doIt();
-  expect(store1.getState()).toEqual(1);
-  store1.dispatch.doIt();
-  expect(store1.getState()).toEqual(2);
-  updux.actions;
+    expect(tracer).not.toHaveBeenCalled();
 
-  const store2 = updux.createStore();
-  store2.dispatch.doIt();
-  expect(store2.getState()).toEqual(1);
+    store.dispatch({ type: 'bar' });
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch.foo();
+
+    expect(tracer).toHaveBeenCalled();
+});
+
+test('effect and sub-effect', () => {
+    const tracer = jest.fn();
+
+    const tracerEffect = (signature: string) => (api: any) => (next: any) => (
+        action: any
+    ) => {
+        tracer(signature);
+        next(action);
+    };
+
+    const store = new Updux({
+        effects: {
+            foo: tracerEffect('root'),
+        },
+        subduxes: {
+            zzz: {
+                effects: {
+                    foo: tracerEffect('child'),
+                },
+            },
+        },
+    }).createStore();
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch({ type: 'bar' });
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch.foo();
+
+    expect(tracer).toHaveBeenNthCalledWith(1, 'root');
+    expect(tracer).toHaveBeenNthCalledWith(2, 'child');
+});
+
+describe('"*" effect', () => {
+    test('from the constructor', () => {
+        const tracer = jest.fn();
+
+        const store = new Updux({
+            effects: {
+                '*': api => next => action => {
+                    tracer();
+                    next(action);
+                },
+            },
+        }).createStore();
+
+        expect(tracer).not.toHaveBeenCalled();
+
+        store.dispatch({ type: 'bar' });
+
+        expect(tracer).toHaveBeenCalled();
+    });
+
+    test('from addEffect', () => {
+        const tracer = jest.fn();
+
+        const updux = new Updux({});
+
+        updux.addEffect('*', api => next => action => {
+            tracer();
+            next(action);
+        });
+
+        expect(tracer).not.toHaveBeenCalled();
+
+        updux.createStore().dispatch({ type: 'bar' });
+
+        expect(tracer).toHaveBeenCalled();
+    });
+
+    test('action can be modified', () => {
+
+        const mw = mwUpdux.middleware;
+
+        const next = jest.fn();
+
+        mw({dispatch:{}} as any)(next as any)({type: 'bar'});
+
+        expect(next).toHaveBeenCalled();
+
+        expect(next.mock.calls[0][0]).toMatchObject({meta: 'gotcha'});
+    });
+});
+
+test('async effect', async () => {
+    function timeout(ms: number) {
+        return new Promise(resolve => setTimeout(resolve, ms));
+    }
+
+    const tracer = jest.fn();
+
+    const store = new Updux({
+        effects: {
+            foo: api => next => async action => {
+                next(action);
+                await timeout(1000);
+                tracer();
+            },
+        },
+    }).createStore();
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    store.dispatch.foo();
+
+    expect(tracer).not.toHaveBeenCalled();
+
+    await timeout(1000);
+
+    expect(tracer).toHaveBeenCalled();
+});
+
+test('getState is local', () => {
+    let childState;
+    let rootState;
+    let rootFromChild;
+
+    const child = new Updux({
+        initial: { alpha: 12 },
+        effects: {
+            doIt: ({ getState, getRootState }) => next => action => {
+                childState = getState();
+                rootFromChild = getRootState();
+                next(action);
+            },
+        },
+    });
+
+    const root = new Updux({
+        initial: { beta: 24 },
+        subduxes: { child },
+        effects: {
+            doIt: ({ getState }) => next => action => {
+                rootState = getState();
+                next(action);
+            },
+        },
+    });
+
+    const store = root.createStore();
+    store.dispatch.doIt();
+
+    expect(rootState).toEqual({ beta: 24, child: { alpha: 12 } });
+    expect(rootFromChild).toEqual({ beta: 24, child: { alpha: 12 } });
+    expect(childState).toEqual({ alpha: 12 });
+});
+
+test('middleware as map', () => {
+    let childState;
+    let rootState;
+    let rootFromChild;
+
+    const doIt = actionCreator('doIt');
+
+    const child = new Updux({
+        initial: '',
+        effects: [
+            [
+                doIt,
+                () => next => action => {
+                    next(
+                        u(
+                            { payload: (p: string) => p + 'Child' },
+                            action
+                        ) as any
+                    );
+                },
+            ],
+        ],
+    });
+
+    const root = new Updux({
+        initial: { message: '' },
+        subduxes: { child },
+        effects: [
+            [
+                '^',
+                () => next => action => {
+                    next(
+                        u({ payload: (p: string) => p + 'Pre' }, action) as any
+                    );
+                },
+            ],
+            [
+                doIt,
+                () => next => action => {
+                    next(
+                        u({ payload: (p: string) => p + 'Root' }, action) as any
+                    );
+                },
+            ],
+            [
+                '*',
+                () => next => action => {
+                    next(
+                        u(
+                            { payload: (p: string) => p + 'After' },
+                            action
+                        ) as any
+                    );
+                },
+            ],
+            [
+                '$',
+                () => next => action => {
+                    next(
+                        u({ payload: (p: string) => p + 'End' }, action) as any
+                    );
+                },
+            ],
+        ],
+        mutations: [[doIt, (message: any) => () => ({ message })]],
+    });
+
+    const store = root.createStore();
+    store.dispatch.doIt('');
+
+    expect(store.getState()).toEqual({ message: 'PreRootAfterChildEnd' });
+});
+
+test('generator', () => {
+    const updux = new Updux({
+        initial: 0,
+        mutations: [['doIt', payload => () => payload]],
+        effects: [
+            [
+                'doIt',
+                () => {
+                    let i = 0;
+                    return () => (next: any) => (action: any) =>
+                        next({ ...action, payload: ++i });
+                },
+                true,
+            ],
+        ],
+    });
+
+    const store1 = updux.createStore();
+    store1.dispatch.doIt();
+    expect(store1.getState()).toEqual(1);
+    store1.dispatch.doIt();
+    expect(store1.getState()).toEqual(2);
+    updux.actions;
+
+    const store2 = updux.createStore();
+    store2.dispatch.doIt();
+    expect(store2.getState()).toEqual(1);
 });
diff --git a/src/middleware_aux.ts b/src/middleware_aux.ts
new file mode 100644
index 0000000..47ab313
--- /dev/null
+++ b/src/middleware_aux.ts
@@ -0,0 +1,13 @@
+import Updux from '.';
+
+const updux = new Updux({
+    subduxes: {
+        foo: { initial: "banana" }
+    }
+});
+
+updux.addEffect('*', api => next => action => {
+    next({...action, meta: "gotcha" });
+});
+
+export default updux;
diff --git a/src/selectors.test.ts b/src/selectors.test.ts
new file mode 100644
index 0000000..29feabe
--- /dev/null
+++ b/src/selectors.test.ts
@@ -0,0 +1,55 @@
+import Updux from '.';
+
+test('basic selectors', () => {
+    const updux = new Updux({
+        subduxes: {
+            bogeys: {
+                selectors: {
+                    bogey: (bogeys: any) => (id: string) => bogeys[id],
+                },
+            },
+        },
+        selectors: {
+            bogeys: ({ bogeys }: any) => bogeys,
+        },
+    });
+
+    const state = {
+        bogeys: {
+            foo: 1,
+            bar: 2,
+        },
+    };
+
+    expect(updux.selectors.bogeys(state)).toEqual({ foo: 1, bar: 2 });
+    expect((updux.selectors.bogey(state) as any)('foo')).toEqual(1);
+});
+
+test('available in the middleware', () => {
+    const updux = new Updux({
+        subduxes: {
+            bogeys: {
+                initial: { enkidu: 'foo' },
+                selectors: {
+                    bogey: (bogeys: any) => (id: string) => bogeys[id],
+                },
+            },
+        },
+        effects: {
+            doIt: ({ selectors: { bogey }, getState }) => next => action => {
+                next({
+                    ...action,
+                    payload: bogey(getState())('enkidu'),
+                });
+            },
+        },
+        mutations: {
+            doIt: payload => state => ({ ...state, payload }),
+        },
+    });
+
+    const store = updux.createStore();
+    store.dispatch.doIt();
+
+    expect(store.getState()).toMatchObject({ payload: 'foo' });
+});
diff --git a/src/types.ts b/src/types.ts
index ca0da78..98e2bcf 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -98,6 +98,8 @@ export type UpduxConfig<S = any> = {
     [type: string]: ActionCreator;
   };
 
+  selectors?: Dictionary<Selector>;
+
   /**
    * Object mapping actions to the associated state mutation.
    *
@@ -198,7 +200,10 @@ export interface UpduxMiddlewareAPI<S> {
   dispatch: UpduxDispatch;
   getState(): any;
   getRootState(): S;
+  selectors: Dictionary<Selector>;
 }
 export type UpduxMiddleware<S = any> = (
   api: UpduxMiddlewareAPI<S>
 ) => (next: UpduxDispatch) => (action: Action) => any;
+
+export type Selector<S = any> = (state:S) => any;
diff --git a/src/updux.ts b/src/updux.ts
index 2df48c3..9f46c59 100644
--- a/src/updux.ts
+++ b/src/updux.ts
@@ -18,10 +18,12 @@ import {
   UpduxDispatch,
   UpduxMiddleware,
   MutationEntry,
-  EffectEntry
+  EffectEntry,
+  Selector
 } from "./types";
 
 import { Middleware, Store, PreloadedState } from "redux";
+import buildSelectors from "./buildSelectors";
 export { actionCreator } from "./buildActions";
 
 type StoreWithDispatchActions<
@@ -44,26 +46,34 @@ export type Dux<S> = Pick<
 >;
 
 export class Updux<S = any> {
-  subduxes: Dictionary<Updux>;
+   subduxes: Dictionary<Updux> = {};
+
+   private local_selectors: Dictionary<Selector<S>> = {};
 
    initial: S;
 
    groomMutations: (mutation: Mutation<S>) => Mutation<S>;
 
-  private localEffects: EffectEntry<S>[] = [];
 
-  private localActions: Dictionary<ActionCreator> = {};
+   private localEffects: EffectEntry<S>[] = [];
 
-  private localMutations: Dictionary<
+   private localActions: Dictionary<ActionCreator> = {};
+
+   private localMutations: Dictionary<
     Mutation<S> | [Mutation<S>, boolean | undefined]
   > = {};
 
   constructor(config: UpduxConfig = {}) {
     this.groomMutations = config.groomMutations || ((x: Mutation<S>) => x);
 
-    this.subduxes = fp.mapValues((value: UpduxConfig | Updux) =>
-      fp.isPlainObject(value) ? new Updux(value) : value
-    )(fp.getOr({}, "subduxes", config)) as Dictionary<Updux>;
+    const selectors = fp.getOr( {}, 'selectors', config ) as Dictionary<Selector>;
+    Object.entries(selectors).forEach( ([name,sel]: [string,Function]) => this.addSelector(name,sel as Selector) );
+
+    Object.entries( fp.mapValues((value: UpduxConfig | Updux) =>
+      fp.isPlainObject(value) ? new Updux(value as any) : value
+    )(fp.getOr({}, "subduxes", config))).forEach(
+        ([slice,sub]) => this.subduxes[slice] = sub as any
+    );
 
     const actions = fp.getOr({}, "actions", config);
     Object.entries(actions).forEach(([type, payload]: [string, any]): any =>
@@ -96,7 +106,6 @@ export class Updux<S = any> {
   }
 
    get actions(): Dictionary<ActionCreator> {
-
     return buildActions([
       ...(Object.entries(this.localActions) as any),
       ...(fp.flatten(
@@ -108,7 +117,7 @@ export class Updux<S = any> {
     ]);
   }
 
-  get upreducer(): Upreducer<S> {
+   get upreducer(): Upreducer<S> {
     return buildUpreducer(this.initial, this.mutations);
   }
 
@@ -191,22 +200,21 @@ export class Updux<S = any> {
   get _middlewareEntries() {
     const groupByOrder = (mws: any) =>
       fp.groupBy(
-        ([_, actionType]: any) =>
+        ([a,b, actionType]: any) =>
           ["^", "$"].includes(actionType) ? actionType : "middle",
         mws
       );
 
     let subs = fp.flow([
-      fp.mapValues("_middlewareEntries"),
       fp.toPairs,
-      fp.map(([slice, entries]) =>
-        entries.map(([ps, ...args]: any) => [[slice, ...ps], ...args])
+      fp.map(([slice, updux]) =>
+        updux._middlewareEntries.map(([u, ps, ...args]: any) => [u,[slice, ...ps], ...args])
       ),
       fp.flatten,
       groupByOrder
     ])(this.subduxes);
 
-    let local = groupByOrder(this.localEffects.map(x => [[], ...x]));
+    let local = groupByOrder(this.localEffects.map(x => [this,[], ...x]));
 
     return fp.flatten(
       [
@@ -219,6 +227,14 @@ export class Updux<S = any> {
       ].filter(x => x)
     );
   }
+
+  addSelector( name: string, selector: Selector) {
+      this.local_selectors[name] = selector;
+  }
+
+   get selectors() {
+        return buildSelectors(this.local_selectors, this.subduxes);
+  }
 }
 
 export default Updux;