const promise = new Promise((resolve, reject) => { console.log(value) })
// promise is not reusable because it's already been called!

const promiseLazy = () => new Promise((resolve, reject) => { console.log(value)})
// wrapping a promise in a function is just a promise getter

// if we allow promises to lazy we can
const promiseAPlusPlus = fetchButBetter('api.cool/123/details').then(parse).then(map)
promiseAPlusPlus.run('adam#123')

// Alternatively Brian McKenna
promiseAPlusPlus.done()

// Assumes promises are lazy
const query = clientDB
	.map(fnMapValue)  // map over value like we would with arrays
	.flatMap(value => anotherAction(value)) // flatten a value like we would arrays

// Run the query
query.run('connection123')

const query = clientDB('connection123')
	.map(fnMapValue)  // map over value like we would with arrays
	.flatMap(value => anotherPromise(value)) // flatten a value like we would arrays

// Run the query
query.done()

// If a promise has an explicit error to be handled
const getDBData = (id) => {
  db.conncet()
  
  return db.query(id)
}

getDBData
  .onRejected((error) => {
    switch error {
      // a more useful switch to handle different errors
    }
  })
  .done(res => {}) // uncaught exceptions prevent the Promise from settling

// Tasks are lazy by default so they can be reused!
// They use Promises under the hood, hence the await (or use .then)
const ioTask = Task.of(1)

await ioTask() // can never fail and returns 1

// or maybe something more practical, also can be resused
// we get common methods for free like map and chain
const result = pipe(
  ioTask,
  T.map(n => n + 1), // map is array.map
  T.chain(n => T.of(n + 2)) // chain is array.flatMap
)

await result() // returns 4

// Under the hood just a Task that returns an Either
const successOnly = TE.right(1)
const failOnly = TE.left(2)

const result = pipe(
  successOnly
  TE.chain(n => failOnly()),
)

await result() // E.left(2)

// Error handling is explicit if you want to get the result
await result()
  .fold(
    error => console.log(error), 
    success => console.log(success)
)