Currying with ES6 fat arrows

logger-middleware.js

// example taken from redux middleware docs : http://gaearon.github.io/redux/docs/advanced/Middleware.html

// ES5
function logger (store) {
  return function (next) {
    return function (action) {
      console.log('dispatching', action);
      var result = next(action);
      console.log('next state', store.getState());
      return result;
    };
  }
}

// ES6
const logger = store => next => action => {
  console.log('dispatching', action);
  let result = next(action);
  console.log('next state', store.getState());
  return result;
};