FP pipe and compose util functions in ES2015

fp.js

// Pipe
const pipe = (...fns) =>
                (...input) =>
                  fns.reduce(function(input, fn) {
                    if (typeof fn !== 'function') {
                      throw Error(`expect a "function" instead got "${typeof fn}".`);
                    }
                    return fn(...[].concat(input));
                  }, input);

// Compose
const compose = (...fns) => pipe(...fns.reverse());