SOURCE

// ********************************************************************
// 工具函数
function splat(fun) {
  return function(array) {
    return fun.apply(null, array);
  };
}

function existy(x) {
  return x != null
};

function cat() {
  var head = _.first(arguments);
  if (existy(head)) return head.concat.apply(head, _.rest(arguments));
  else return [];
}

function construct(head, tail) {
  return cat([head], _.toArray(tail));
}

function second(arr) {
  return arr[1];
}

function partial1(fun, arg1) {
  return function(/* args */) {
    var args = construct(arg1, arguments);
    return fun.apply(fun, args);
  };
}
// ********************************************************************
function evenOline(n) {
  if (n === 0)
    return true;
  else
    return partial1(oddOline, Math.abs(n) - 1);
}

function oddOline(n) {
  if (n === 0)
    return false;
  else
    return partial1(evenOline, Math.abs(n) - 1);
}

function trampoline(fun /*, args */) {
  var result = fun.apply(fun, _.rest(arguments));

  while (_.isFunction(result)) {
    result = result();
  }

  return result;
}

var rs = trampoline(evenOline, 6);
console.log(rs);