备忘

http://www.jdon.com/idea/monad.html

http://blog.leichunfeng.com/blog/2015/11/08/functor-applicative-and-monad/

http://www.jdon.com/idea/functor-monad.html

http://www.jdon.com/designpatterns/functional-patterns-identity.html

http://www.jdon.com/46884

http://www.jdon.com/idea/monoid.html

http://www.jdon.com/idea/monad.html

https://www.cnblogs.com/wujy/p/4950591.html

http://blog.leichunfeng.com/blog/2015/12/25/reactivecocoa-v2-dot-5-yuan-ma-jie-xi-zhi-jia-gou-zong-lan/

https://www.jianshu.com/p/e0b0afd0519f

http://blog.csdn.net/chenyin10011991/article/details/51971388

https://www.raywenderlich.com/62699/reactivecocoa-tutorial-pt1