Synchronous chain

syncChain.js

function chain() {
  var queue = []
  function chainer(func) {
    queue.push(function (x) {return func(x)})
    return chainer
  }
  chainer.run = function () {
    queue.reduce(function (previous, func) {return func(previous)}, undefined)
  }
  return chainer
}

// Example
chain()
  (just([1,2,3,4,5,6]))
  (filter(even))
  (map(double))
  (print)
  .run()
  
// Details
function filter(func) {return function (arr) {return arr.filter(func)}}
function map(func)    {return function (arr) {return arr.map(func)}}
function just(x)      {return function () {return x}}

function even(x)   {return x%2==0}
function double(x) {return x*2}

function print(x) {console.log(x)}