Functional programming helpers for Redux.
Table of contents
Updater is a type of function that takes an action and returns another function that takes the state and produces a result.
action => state => {
// Do something
}Yes, they are just curried reducers with reversed argument order.
Unlike reducers, updaters compose nicely with existing tools like lodash/fp or Ramda.
Let's create an updater that replaces a part
of the state with the action's payload. We will use lodash/fp's set helper to illustrate the point.
import { set } from 'lodash/fp'
const changeFoo = action => set('foo', action.payload)Note that I've eliminated state from the definition of our updater, and called set with two, not three, arguments.
This works because when set is called without
the third argument, it returns a function that takes the missing argument and produces a result.
That function becomes the inner function of our updater and receives the state.
The paradigm is called point-free style, and if you're not familiar with it, check out Lucas Reis' introductory article.
To create a Redux store, just wrap the root updater in a reducer:
createStore((s, a) => updater(a)(s))redux-fp provides a set of useful utilities and enhancers like combine, withDefaultState or mapState
that help working with updaters.
Check out the API reference for a full list of helpers, complete with descriptions and usage examples.
Node
npm i --save redux-fp
Or as a development dependency:
npm i --save-dev redux-fp
Browser
<script src="https://unpkg.com/redux-fp/dist/redux-fp.min.js"></script>Makes the library available globally as ReduxFp.
See docs/API.md