http://learnyouahaskell.com/for-a-few-monads-more http://brandon.si/code/the-state-monad-a-tutorial-for-the-confused/ https://hackernoon.com/the-reader-monad-part-1-1e4d947983a8 https://medium.com/@jonathangfischoff/monad-reader-part-2-d812dda1d03e
https://www.schoolofhaskell.com/user/commercial/content/monad-transformers https://two-wrongs.com/a-gentle-introduction-to-monad-transformers http://book.realworldhaskell.org/read/monad-transformers.html
https://begriffs.com/posts/2017-04-09-monad-tutorial-workshop.html