[Compose] 10. Capture Side Effects in a Task

We examine the data structure Task, see some constructors, familiar methods, and finally how it captures side effects through laziness.

 

We using a 'data.task' library. It is a bit similar to $q library in Angular. Accepts one function, function takes two params, 'reject function' & 'resolve function'. 

import Task from 'data.task';


const launchMissiles = () =>
  new Task((rej, res) => {
    console.log('launch missiles!')
    res('missile')
  })

 

Because this is laziness, therefore, we can compose logic based on that:

const app = launchMissiles().map(x => x + '!')

app
.map(x => x + '!')
.fork(e => console.error('err', e),
      x => console.log('success', x))

 

If inside 'lauchMissiles' call 'reject' function, all the map function chaining on app won't be called anymore.

'fork' is the actually function which trigger it works.

-----

import Task from 'data.task';


const launchMissiles = () =>
  new Task((rej, res) => {
    console.log('launch missiles!')
    res('missile')
  })

const app = launchMissiles().map(x => x + '!')

app
.map(x => x + '!')
.fork(e => console.error('err', e),
      x => console.log('success', x))

//launch missiles!
success