Promise!01!

p.js

const _data = (data) => ({ error: null, data }) 
const _error = (error) => ({ data: null, error })

const mapError = f => ({ error, data }) => ({ error: f(error), data }) 
const mapData = f => ({ error, data }) => ({ data: f(data), error })

const promiseMapData = f => p => p.then(f)
const promiseMapError = f => p => p.catch(f)

const promiseMe = (p) => pipe(
  	p, 
  	promiseMapData(_data), 
  	promiseMapError(_error)
 )

const input = promiseMe(Promise.resolve(1))
// Promise {data: 1, error: null}

const jsonFromRest = pipe(
	fetch('/x'),
  	promiseMapData(r => r.json()),
  	promiseMe,
)

// ✅: Promise { data: {ping: 1}, error: null  } 
// ❌: Promise { data: null, error: "FAFIFUFE" }