Find Out Functional Programming Style from Redux

Prior to I set my eyes on the Redux source code, I naively believed OOP goes beyond than FP( Practical Programs) as a programs paradigm. This is wrong. As we comprehend that FP is committed to forming a simple to understand and clear workflow without those odd abstracted things and relations. It’s much closer to human’s procedural mode of thinking.

Now React has currently got hooks which can handle the “states” effectively celebration withoutRedux The demand for Redux might be reducing nevertheless its code base is still worth finding. Particularly for those who wishes to inform themselves in usefulprograms I believe it’s never ever a bad principle to acquire from a good example although it is “outdated” (not).

When I started examining out the Redux source code, I right away felt the power of this unidentified use of my familiar showslanguage It feels like monitoring out an acient cavern with a torch lighting up the paintings and found the exceptional trick.

In order to comprehend more about what Redux capitalize of FP, I examined the Redux source code and developed a mini version of it.

Never ever think twice of transforming the wheel.


  • Wrap-up How Redux Functions
  • Redux Technique Contrast: FP vs OOP
  • Fantastic Redux FP Style
    • createStore
    • combineReducers
    • applyMiddleware
  • Redux Middlewares
    • Redux Thunk
    • Redux Logger
  • A presentation app
  • Conclusion
  • Recommendations

Wrap-up How Redux Functions

There are 4 basic key points for Redux:

  1. Produce a store for info and let the view subscribe to it
  2. The view dispatches an action to send out the changs
  3. The reducer changes the state based upon the action type
  4. Last but not least return the new state and triggers the view to modify

This is the conventional diagram going over how Redux works:

redux diagram

From the diagram above, it’s simple to find the keywords: action store reducer view subscribe and dispatch And the next is to handle the relations amongst these keywords.

Redux Strategy Contrast: FP vs OOP

Example use of Redux

 const shop = ((*********************** )createStore(
.(*********************** )combineReducers(),
.(*********************** )applyMiddleware((*********************** )ReduxThunk,(*********************** )ReduxLogger)
.); (

Envision if we do this in OOP, it might look like this:

( The following is just my imagination. Not how older Redux acts)

 const store = ((*********************** )brand name-new(*********************** )Store()
.store(*********************** )setReducers()
shop setMiddlewares(

So, what are the distinctions? Both are good approaches IMO.

FP does an exceptional job on integrating the functions together without side- impacts. The return worth corresponds which made the program returnings foreseeable throughout or after the execution.

OOP made a strong structure which defined all the attributes an info design should consist of. It makes it simple to personalize or set up the information model.

In Redux, the reduers and middlewares are normally defined just when. It indicates, we do not need the ability to update these business or domestic homes and we do not hope them to be altered throughout the runtime. As for FP technique, it makes use of the closure technique that kills the possbility of exposing the internalhomes With some terrific FP strategies (curry, make up, pipeline), it’s even making the program a lot more human-readable than OOP.

I would state FP should be the best fit for such situation. Naturally, the FP I’m going over here is far from the real useful shows like Haskell. At least the concept of making use of FP strategies in Javascript is something to follow.

haskell functional programming

Terrific Redux FP Style

In Redux, there is no class at all (In the earlier variations, it was as soon as based upon Class). All of its core APIs return either worth or function (function factory). And this is precisely what FP anticipates a function to act:

Pure with no unfavorable impacts.

  • createStore: returns new Item getState, dispatch, subscribe
  • combineReducers: returns brand name-new Function
  • applyMiddleware: returns new Function

To discuss the Redux design in a simple way, I carried out just the truly core part of the APIs above. Given that the most current variation’s core concept hasn’t modified much, I composed the source code based upon extremely primitive variation of Redux v1.0.1. Given that I believe the truly first associated version would be the most substantial one to take a look at.

Let’s take a look.


createStore specifies those APIs that can be made use of within aspects. It’s more like setter and getter

  • getState
  • dispatch
  • subscribe
 export default function createStore( reducer, enhancer)
If( enhancer),
 return enhancer( createStore)( reducer);(.(************************

).(*********************** )let(************************ )currentState;(.(*********************** )let currentListeners = ([];(.(*********************** )function(*********************** )getState()
.(*********************** )return(************************ )currentState;(.(************************

).(*********************** )function(*********************** )subscribe((*********************** )listener)
. currentListeners(*********************** )push( listener);(.(*********************** )return()>= >

.(*********************** )const index =( currentListeners indexOf( listener);(.
currentListeners splice( index, 1);(.;(.(************************

).(*********************** )function(*********************** )dispatch((*********************** )action)

.(*********************** )dispatch();(.(*********************** )return
. getState,
. dispatch,

combineReducers(***************************** )

Returns a brand name-new function that can return the new state. Can’t be any purer.

 function mapValues( obj, fn)

 export default function combineReducers( reducers) 


I personally think the applyMiddleware API is the most fantastic part of Redux.

The FP make up in the source code is representing Mathematics’s associative law in my understanding.

( x & lowast; ( y & lowast; z)) = x & lowast; y & lowast; z

The use of applyMiddleware is really a kind of a pipeline that allows us to inject improvement operates that returns the shop Things.

function make up( funcs)
return funcs reduceRight(( made up, f)=>> f( made up));(.(************************

).(*********************** )export(*********************** )default(*********************** )function(*********************** )applyMiddleware( middlewares)

All of the middlewares are curry functions.

funcA=> > funcB=> > funcC

funcB= funcA()

funcC= funcB()

This is extremly useful when I need other contexts to use within the code block.

Redux Thunk

redux- thunk allows to make use of function as dispatch spec so that I may do something right prior to”dispatching”

dispatch( function( dispatch, getState)
console log(‘ redux- thunk’)

Here is the core:

 export default function thunk( dispatch, getState  )
 return next=>> action=>> ;(.

Redux Logger

It’s basic to think what this middleware does. It merely outputs the state(************************************************************************************************************************************************************************************************************************** ).

A demonstration app

I broughtout mini versionofredux and asmall counter application to demostrate the functions.

Repository linkof”mini-redux”:

Demonstration App link:


The app hasone kid component: MiniReduxCompfrom‘ react’;(. importshopfrom‘./(****************************************************************************************************************************************************************************************************************************************** )’ export default class MiniReduxComp extends Aspect(*********************** )(************************ ) Plus/ Minus 1 > -1 Multiply/ Divide 2( 0.3 s hold-up)

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