consequence function return type

Consequences can also return a function. When this happens the consequence will be active forever and can only be canceled when the rule is removed (e.g by addUntil) or a concurrency event happens. The returned function will be called after the consequence was canceled.

This is very usefull when it comes to sockets. Let's say we have socket api (like firebase) that listens to the auth-state of the user:

import {addRule} from 'redux-ruleset``
import authApi from 'my-api'

addRule({
  id: 'LOGIN_OBSERVER',
  target: '*',
  concurrency: 'FIRST',
  consequence: (_,{dispatch}) => {
    const unlisten = authApi.onAuthStateChange(user => {
      if(user) dispatch({ type: 'LOGIN', payload: user })
      else dispatch({ type: 'LOGOUT' })
    })
    return unlisten
  }
})

You can read more about handling streams in the handle streams section