Reducer to handle created actions

reducer.js

import * as types from "./actionTypes"
import Immutable from "seamless-immutable"

const initialState = Immutable({
    posts: undefined,
    postsIsFetched: false
})


export default function postsReducer(state=initialState, action={}){
    switch (action.type) {
        case types.POSTS_RECEIVED:            
            return state.merge({
                posts: action.payload,
                postsIsFetched: true
            })
        default:
            return state
    }
}