diff --git a/src/redux-arg/constants.js b/src/redux-arg/constants.js
index 8abe6e7..4a771f6 100644
--- a/src/redux-arg/constants.js
+++ b/src/redux-arg/constants.js
@@ -6,11 +6,6 @@ export const PROP_TYPES = {
     _array: '_array',
 };
 
-export const TYPE_DEFAULTS = new Map([
-    [PROP_TYPES._string, ''],
-    [PROP_TYPES._number, 0],
-]);
-
 export const Types = {
     string: () => ({ type: PROP_TYPES._string, structure: PROP_TYPES._string }),
     number: () => ({ type: PROP_TYPES._number, structure: PROP_TYPES._number }),
diff --git a/src/redux-arg/generateReducer.js b/src/redux-arg/generateReducer.js
index 2aa5f01..3080669 100644
--- a/src/redux-arg/generateReducer.js
+++ b/src/redux-arg/generateReducer.js
@@ -1,10 +1,12 @@
 //@flow
+import type { ReducerStructure } from './structure';
+
 import { combineReducers } from 'redux';
 import { reduce, find } from 'lodash';
 import { createReducer } from './reducers';
 import { PROP_TYPES } from './constants';
 
-export function buildReducers(structure) {
+export function buildReducers(structure: ReducerStructure) {
 
     const tmp = combineReducers(reduce(structure, (memo, propValue, propName) => {
         const { structure } = propValue();
diff --git a/src/redux-arg/reducers.js b/src/redux-arg/reducers.js
index b2feb98..50f6f3d 100644
--- a/src/redux-arg/reducers.js
+++ b/src/redux-arg/reducers.js
@@ -3,12 +3,11 @@ import {
     PROP_TYPES,
     TYPE_DEFAULTS,
 } from './constants';
-import {
-    reduce
-} from 'lodash';
-import {
-    compose
-} from 'ramda';
+import { reduce } from 'lodash';
+import { compose } from 'ramda';
+import { primitiveReducer } from './reducers/primitiveReducer';
+import { objectReducer } from './reducers/objectReducer';
+import { arrayReducer } from './reducers/arrayReducer';
 
 const DEFAULTS_FUNCTIONS = new Map([
     [PROP_TYPES._shape, objectDefaults],
@@ -36,9 +35,9 @@ function determineReducerType(reducerDescriptor) {
     const { structure } = reducerDescriptor();
     const { type } = structure();
 
-    let reducerFn = REDUCER_FUNCTIONS.primitiveReducer;
-    if (type === PROP_TYPES._shape) reducerFn = REDUCER_FUNCTIONS.objectReducer;
-    if (type === PROP_TYPES._array) reducerFn = REDUCER_FUNCTIONS.arrayReducer;
+    let reducerFn = primitiveReducer;
+    if (type === PROP_TYPES._shape) reducerFn = objectReducer;
+    if (type === PROP_TYPES._array) reducerFn = arrayReducer;
     return {
         reducerFn,
         reducerStructureDescriptor: structure,
diff --git a/src/redux-arg/reducers/primitiveReducer.js b/src/redux-arg/reducers/primitiveReducer.js
index 3d7de3e..07d68b0 100644
--- a/src/redux-arg/reducers/primitiveReducer.js
+++ b/src/redux-arg/reducers/primitiveReducer.js
@@ -1,17 +1,18 @@
 //@flow
-type Primitive = string | number;
-type PrimitiveReducerAction = {
-    type: string,
-    payload?: string | number,
-};
-type PrimitiveReducer = (Primitive) => (Primitive, PrimitiveReducerAction) => Primitive;
+import type { ReducerStructure } from '../structure';
 
-export function primitiveReducer(reducerStructureDescriptor): PrimitiveReducer {
-    const { structure } = reducerStructureDescriptor();
-    return (state = determineDefaults(reducerStructureDescriptor)(structure), { type, payload } = {}) => {
+export type ObjectReducerAction = {
+    type: string,
+    payload?: Object,
+};
+export type ObjectReducerFactory = (structure: Object) => ObjectReducer;
+export type ObjectReducer = (state: Object, action: ObjectReducerAction) => Object;
+
+export function arrayReducer<ArrayReducerFactory>(reducerStructureDescriptor: ReducerStructure) {
+    return(state: Object = calculateDefaults(reducerSructure), { type, payload = {}}: ObjectReducerAction = {}): Object => {
         switch(type) {
-            case 'BLARG2':
-                return { state, ...structure, ...payload };
+            case 'BLARG3':
+                return [ state, ...payload ];
             default:
                 return state;
         }
diff --git a/src/redux-arg/structure.js b/src/redux-arg/structure.js
index a4a2794..7d7c7d5 100644
--- a/src/redux-arg/structure.js
+++ b/src/redux-arg/structure.js
@@ -4,13 +4,30 @@
 // Flow types
 //==============================
 export type ReducerStructure = {
-    [key: string]: StructureType
+    [key: string]: StructureType|PrimitiveType,
+}
+export type StructureType = () => {
+    type: string,
+    structure: StructureType|ReducerStructure
+};
+export type PrimitiveType = () => {
+    type: string,
+    structure: $Keys<typeof PROP_TYPES>,
+    defaultValue: ?any,
+};
+
+export type TypesObject = {
+    [key: string]: CreateStructure|CreateStringType|CreateNumberType
 }
 
-export type StructureType = (structure: ?ReducerStructure) => {
-    type: string,
-    structure: [StructureType | ReducerStructure]
-};
+export type TypesObjectDefaults = {
+    [key: string]: mixed|TypesArrayDefaults,
+}
+export type TypesArrayDefaults = Array<mixed>|Array<TypesObjectDefaults>;
+
+type CreateStringType = (defaultValue: string) => PrimitiveType;
+type CreateNumberType = (defaultValue: number) => PrimitiveType;
+type CreateStructure = (structure: ReducerStructure, defaultValue: TypesArrayDefaults|TypesObjectDefaults) => StructureType;
 
 //==============================
 // Structure
@@ -23,14 +40,9 @@ export const PROP_TYPES = {
     _array: '_array',
 };
 
-export const TYPE_DEFAULTS = new Map([
-    [PROP_TYPES._string, ''],
-    [PROP_TYPES._number, 0],
-]);
-
-export const Types = {
-    string: () => ({ type: PROP_TYPES._string, structure: PROP_TYPES._string }),
-    number: () => ({ type: PROP_TYPES._number, structure: PROP_TYPES._number }),
+export const Types: TypesObject = {
+    string: (defaultValue: string = '') => () => ({ type: PROP_TYPES._string, structure: PROP_TYPES._string, defaultValue }),
+    number: (defaultValue: number = 0) => () => ({ type: PROP_TYPES._number, structure: PROP_TYPES._number, defaultValue }),
     arrayOf: (structure: ReducerStructure) => () => ({ type: PROP_TYPES._array, structure }),
     reducer: (structure: ReducerStructure) => () => ({ type: PROP_TYPES._reducer, structure }),
     shape: (structure: ReducerStructure) => () => ({ type: PROP_TYPES._shape, structure}),