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Rereduce

Simple reducer library for Redux. It's like Reselect but for reducers.

By using aggressive memoization, reducers can depend on each others in an efficient way, without having to query Redux store.

It works fine with time-travel debugging and server-side rendering, because reducers remains totally stateless pure functions.

It permits to replace the imperative waitFor of original Flux implementation by a purely functional approach.

API

The API is a first draft and may change in the future. Don't hesitate to discuss what the API should look like here: https://github.com/slorber/rereduce/issues/1

createReducer( [reducerDependencies], reducerFunction)

[reducerDependencies] is an optional object that looks like {key1: reducer1, key2: reducer2}

If dependencies are provided, reducerFunction will be called with a 3rd argument with the state of the dependency reducers.

Simple Reducers (without dependencies)

Rereduce only add basic memoization on the original reducer. You don't need to use rereduce for those reducers at all. But if you plan to make other reducers depend on your simple reducer, wrapping it with rereduce will be more CPU and memory efficient.

Reducers with dependencies

Example


import {  createReducer  } from 'rereduce'

const firstReducer =  createReducer((state = 0, action) => {
  switch (action.type) {
    case 'increment': return state + 1
    case 'decrement': return state - 1
    default: return state
  }
})

const secondReducer = createReducer({ firstReducer },
  (state = 0,action,{ firstReducer }) => firstReducer + 1
)

const rootReducer = combineReducers({ firstReducer, secondReducer })

const initialState = undefined
const stateInitialized = rootReducer(initialState,{ type: 'init' })
const stateIncremented = rootReducer(stateInitialized,{ type: 'increment' })

assert.equal(stateInitialized.firstReducer, 0)
assert.equal(stateInitialized.secondReducer.value, 1)

assert.equal(stateIncremented.firstReducer, 1)
assert.equal(stateIncremented.secondReducer.value, 2)

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