calling willMatchWith on a future() has uncaught error of missing 'listen' of undefined

Hi there,

https://codesandbox.io/s/21o6kqn4zr

I made a simple sandbox here to show the problem, please look at the console, it’s the normale console in your browser.

In a nutshell, if we did

import { task } from "folktale/concurrency/task";

const delay = ms =>
  task(res => {
    setTimeout(() => res.resolve(ms), ms);
  });

const taskA = delay(1000);

console.log('taskA')
taskA.run().future().willMatchWith({
  Resolved: console.log,
  Rejected: console.log,
  Canceled: console.log
})

will throw

Uncaught TypeError: Cannot read property 'listen' of undefined
    at Object.onResolved (VM3955 dll.js:19248)
    at Object.Resolved (VM3955 dll.js:10379)
    at InternalConstructor.matchWith (VM3955 dll.js:419)
    at _loop (VM3955 dll.js:10376)
    at moveToState (VM3955 dll.js:10392)
    at Object.onResolved (VM3955 dll.js:10531)
    at Object.Resolved (VM3955 dll.js:10379)
    at InternalConstructor.matchWith (VM3955 dll.js:419)
    at _loop (VM3955 dll.js:10376)
    at moveToState (VM3955 dll.js:10392)
    at Deferred.resolve (VM3955 dll.js:10432)
    at Object.resolve (VM3955 dll.js:11016)
    at eval

[niksosf]

Gotcha! Thanks again, really appreciate it!

[niksosf]

Hey @robotlolita , nice of the authors to put automated check on even the docs, it seems like. – Oh believe me, even the time I spent on researching this will be minor compared with the time I’ll save with the safer code I’ll write with it 😉

That makes a lot of sense, because the way listen is describe elsewhere on the same doc. The way I understand it is that listen is a straightforward unleashing the value to do some side-effect after a one off async action inside the task. Fair enough.

And willMatchWith will be used for continuing chaining/mapping, like you already said, transforming the data.

here’s that snippet on listen