[sketch] Promise as functor in Javascript

promise.js

  var Promise__map = function(g){  // g: a -> b
    var _f = function(){};
    var h = function(f){  // h : (b -> c) -> 0
      _f = f;
    };
    this.fp(function(a){
      var b = g(a);
      _f(b);
      return b;
    });
    return Promise(h);
  }
  var Promise = function(fp){ // fp : (a -> b) -> 0
    return { fp: fp, subscribe: Promise__map };
  };

x = []
function async(f) { x.push(f); }
p = Promise(async);
p1 = p.subscribe(function(n) { return "Number = " + n; });
p2 = p1.subscribe(console.log.bind(console));

x[0](123);