Thenable results

thenable.js

// For bonus points
// * ensure then/catch is always asynchronous
// * flatten f functions that return thenables

class Success {
  constructor(v) {
    this.v = v
  }
  
  then(f) {
    return f(this.v)
  }
  
  catch(f) {
    return this
  }
}

class Failure {
  constructor(v) {
    this.v = v
  }
  
  then(f) {
    return this
  }
  
  catch(f) {
    return f(this.v)
  }
}

/*
const a = () => new Success(1)

const b = (x) => new Promise((r) => {
  r(new Success(x + 1))
})

const c = (x) => x + 1

const d = (x) => Promise.resolve(x + 1)

const err = () => Promise.reject('error')

a()
  .then(b)
  .then(c)
	.then(d)
  .then(x => { console.log(x) })

a()
  .then(b)
	.then(err)
  .then(c)
	.then(d)
  .then(x => { console.log(x) })
	.catch(x => { console.error(x) })
*/