React Most
A Monadic Reactive State Container for React Components
npm install react-most --save
What
most.js
is very high performance Monadic reactive streams lib. Rich User Interaction App is natively fit Reactive Programming pretty well.
React
is awesome for writing UI Components.
So, what react-most
does is simply making you React Components Reactive.
react-most
is simple and only 90 lines of code. only depends on most and react.
data flow is simple and one way only
- Action will generate value and add it into
Intent Stream
- Sink create new Stream based on action type in
Intent Stream
- Sink transform a value Stream into a
oldState=>newState
mapping Stream - State subscribe to Sinks changes
Why not (just using existing state container e.g.) redux
When I play around with redux, it's awesome but
- it take little time to make it ready.
- it's using too many concept that we probably don't even care, which make it's learning curve a little steep(it take a gitbook to document just a state container?)
- Reducers (long switch statements which are syntactically ugly but semantically ok) -- Andre
- switch statement is ugly and hardly composable
- again, I couldn't agree more on Andre's article about react/redux.
Inspired by Reactive Programming, Cycle.js and Redux, we can do something better to reduce the complexity of managing react state, the reactive way, by only introduce a little bit of reactive programming concepts.
Why indeed?
Redux is awesome, but if you're big fan of Functional Reactive Programming, you would've imaged all user events, actions and data are Streams, then we can map,filter, compose, join those streams to React state.
Pure Functional, Declarative & Monadic
finstead of imperative describe what you want to do with data at certain step, we simple define data transforms and compose them to data flow. No variable, no state, no side effort at all while you composing data flow.
Composable and Reusable Sinks
sinks are composable and reusable, not like reducer in redux, where switch statement are hard to break and compose.
Transducers support
transducer is another high perfomance way to compose data flow other then monadic.
writing actions in transducers improve reusablity.
Time Travel
since we have all action's Stream, we can easyliy reproduce all the action anytime, or get snapshot of state stream and going back in time.
you can pass history as 3rd parameter of connect
connect(App, intent$=>[awesome flow], {history:true})
connect will populate history stream with all state history
then you get a create action to deal with historyStream.
Modular and Easy to Extend
if you're from Rx.js, it's easy to switch rx engine into react-most, by simply pass a props named engine
to Most
component
import rxEngine from 'react-most/engine/rx'
<Most engint={rxEngine}>
<App />
</Most>
How
there's only 3 things you should notice when using react-most
, I'll explain by a simple counter app.
1. Component Wrapper
import Most from 'react-most'
<Most>
<Counter />
</Most>
2. Define How to connect Component and Streams
import {connect} from 'react-most'
import most from 'most'
let RxCounter = connect(Counter, function(intent$){
let defaultState$ = most.of(_=>({value:0}))
let addSink$ = intent$.filter(x=>x.type=='add').map(({increment})=>state=>({value: state.value+increment}))
return {
add: increment=>({type: 'add', increment}),
defaultState$,
addSink$,
}
});
here are things you may need to pay attention to:
2.1. transform intent stream to state mapper stream
the transformer accept a Intetent Stream intent$
(by convention, all Stream type variable name with suffix $), and create and return new Intent Streams(here we call those new stream -- sinks
)
let addSink$ = intent$.filter(x=>x.type=='add').map(({increment})=>state=>({value: state.value+increment}))
here we filter out only add
intent and do something about it.
when I mean something, I mean transform intent to be a state transformer. which means Intent Stream of values
--{value: 1}
--{value: 2}
--{value:3}
-->
becomes a Stream of functions which tranform old state into new state
--state=>({value: state.value+1})
--state=>({value: state.value+2})
--state=>({value: state.value+3})
-->
2.2. define action mapper that can be use to added intent to your Intent Stream.
add: increment=>({type: 'add', increment}),
here it define a add
action mapper, it define how you can use the action. it's pretty clear here that the search action will accept only one arg increment
, and {type: 'add', increment}
is something will be send to Intent Stream when action is called.
3. Use the actions
like redux, but much simpler, when you wrap your App, your App get a actions
props, and you can pass it all along to any child Component.
<button className="add1"
type="checkbox"
onClick={()=>this.props.actions.add(1)} />
More Examples
Performance
react-most
no more than creating stream from your actions, and bind it to state stream. no any other computations happen in react-most
. so please refer to most.js's perf which is realy Great!
I also do a simple benchmark with 8k times of performing counter increase action
Memory Usage Before: { rss: 32501760, heapTotal: 16486912, heapUsed: 11307128 }
Memory Usage After: { rss: 34418688, heapTotal: 18550784, heapUsed: 11932336 }
Elapsed 8ms
basically the same level of performance as redux(which is 10ms in the same testing)