define effect creator for hyperapp

fx.js

export default (g => f => (...a) => [g, { f, a }])((d, { f, a }) => f(d, ...a))

/*

Usage like:

import fx from 'fx.js'

const jsonLoader = fx((dispatch, url, then) =>
  fetch(url)
  .then(response => response.json())
  .then(data => dispatch(then, data)
)

...

const LoadAction => (state, url) => [
  {...state, loading: true},
  jsonLoader(url, ResultAction)
]

...or...

const jsonLoader = fx((dispatch, {url, action}) =>
  fetch(url)
  .then(respnse => response.json())
  .then(data => dispatch(action, data))
)

...

const LoadAction => (state, url) => [
  {...state, loading: true},
  jsonLoader({url, action: ResultAction})
]



*/