Demonstrate CPS for array processing

## demo-cps.js
// ==ClosureCompiler==
// @compilation_level ADVANCED_OPTIMIZATIONS
// @output_file_name cps-demo.js
// @formatting pretty_print
// ==/ClosureCompiler==

function forEach(coll, f) {
  for(var i = 0; i < coll.length; ++i) {
    f(coll[i]);
  }
}

function cps_filter(f, x, next) { if(f(x)) next(x); }
function cps_map(f, x, next) { next(f(x)); }

function m1(x) { return x / 2; }
function f2(x) { return x % 2 == 0; }
function m3(x) { return x * 10; }

var input = [2, 4, 6, 8]
var a = [];
forEach(input, function(x1) {
  cps_map(m1, x1, function(x2) {
    cps_filter(f2, x2, function(x2) {
      cps_map(m3, x2, function(x3) {
        a.push(x3); })})})});