Serial execution of functions for flow based programming.

serial.js

/**
 * Take an array of functions that accept one argument and return a value or Promise,
 * and invoke each function serially, passing the resolved value to the next function.
 * 
 * @param {Array} fnArray
 * @param {Mixed} initialValue
 * @return {Promise}
 */
export default (fnArray, initialValue) =>
  fnArray.reduce((chain, fn, index) =>
    index === 0 ? Promise.resolve(fn(initialValue)) :
    chain.then(value => fn(value)))