Compose render props imperatively with async/await/CPS kinda sugar

epita✞h

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Also, we think you may want to take a look on React Hooks API now

import epitath from 'epitath'
...

const App = epitath(function*() {
  const { loading, data } = yield <Query />
  const { time } = yield <Time />

  return (
    <div className="App">
      {loading ? (
        <h1>Loading</h1>
      ) : (
        <div>
          <h1>{`Hello, ${data.user.name}`}</h1>
          <h2>The time is {time.toLocaleString()}!</h2>
        </div>
      )}
    </div>
  )
})

Compose HOCs imperatively like async/await. No callback hell!

Live demo Source of demo

Install

yarn add epitath

or

npm install --save epitath

Why

Render props are amazing for providing more functionality but once you need to stack a bunch of them you get what recalls a painful callback hell.

<Query>
  {({ data }) =>
    <Mutation>
      {({ mutate, result })=>
        <Form>
        etc
        </Form>
      }
    </Mutation>
  }
</Query>

How

Wait, we just mentioned “callback hell”. So what if we had a function that would allow us to have a kind of sugar for continuation-passing-style à la async/await?

And that’s exactly what epitath is, it just takes care of the callbacks for you. The whole code is this:

import React from 'react'
import immutagen from 'immutagen'

export default component => {
  const generator = immutagen(component)

  const compose = context => {
    const value = context.value
    return context.next
      ? React.cloneElement(value, null, values => compose(context.next(values)))
      : value
  }

  function Epitath(props) {
    return compose(generator(props))
  }

  Epitath.displayName = `EpitathContainer(${component.displayName || 'anonymous'})`

  return Epitath
}

Note that epitath will only yield the first argument of the render function. In order to consume multiple arguments, we recommend creating a wrapper component:

const MutationWrapper = ({ children, ...props }) =>
  <Mutation {...props}>{(mutate, result) => children({ mutate, result })}</Mutation>

const { mutate, result } = yield <MutationWrapper />

How is this different from Suspense?

Suspense only allows you to evalulate a promise once. It does not allow you to trigger a re-render for a state update. And with epitath you can even use Formik, Apollo optimistic, React Powerplug and Smalldots tooling and etc!

BTW it’s epitaph not “epitath”

“These Astrocoders dudes simply don’t know how to spell words in English!”

Actually it was intended, for 2 reasons:

1. We wanted to put a cross as icon of the package
2. Epitaph is already taken in NPM

Contributing

Steps to get it running

Install the deps

yarn install

Boot the demo

yarn start

Things missing that we would like a little help

• Tests
• TypeScript support

Acknowledgements

Thanks @jamiebuilds for the suggestions on how simplifying the API

Contributors

Thanks goes to these wonderful people (emoji key):

This project follows the all-contributors specification. Contributions of any kind welcome!