var Future = require ('data.future'),
    R      = require ('ramda'),
    log    = console.log,

    id     = function (x) { return x; },

    trampoline = function (fn) {
      return function () {
        var args = arguments;
        var f = function () { return fn.apply (this, args); }
        while (f && typeof f === 'function') { f = f (); };
        return f;
      };
    },

    sequenceF = function (M, fxs) {
      return R.reduce (_perform, M.of ([]), fxs);

      function _perform (acc, f) {
        var ys,
            setYS = function (v) { ys = v; },
            appYS = function (x) { ys = R.append (x, ys); }

        acc.fork (appYS, setYS)
          f.fork (appYS, appYS);
        return M.of (ys);
      };
    },

    sequence = R.curry (function (M, fxs) {
      return R.reduce (_perform, M.of([]), fxs);

      function _perform (acc, f) {
        return acc.chain (function (xs) {
          return f.chain (function (x) {
            return M.of (R.append (x, xs));
          });
        });
      };
    }),

    nil = null;

(function main () {
  var i = 0, fxs = [];

  for (i = 0; i < 20000 ; i++) {
    fxs = R.append (Future.of (i), fxs);
  }

  sequenceF (Future, fxs).fork (log, log);
//  sequence (Future, fxs).fork (log, log);
})();