Haskell Servant http://taylor.fausak.me/static/pages/2015-08-26-type-safe-web-services-in-haskell-with-servant.html#1
A quick intro about Monads https://medium.com/@franzejr/a-quick-intro-about-monads-291e50dda062#.lis76jf2t
Persistent entity syntax https://github.com/yesodweb/persistent/wiki/Persistent-entity-syntax
Adding a UUID Column to a Persistent Table http://michaelxavier.net/posts/2015-04-14-Adding-a-UUID-Column-to-a-Persistent-Table.html
Persistent in Detail https://www.schoolofhaskell.com/school/advanced-haskell/persistent-in-detail
Grasping Haskell: functors, applicatives and monads (part 1) https://medium.com/@xanderdeseyn/grasping-haskell-functors-applicatives-and-monads-part-1-93368e0a7a74#.wpcqgmxwe
Grasping Haskell: functors, applicatives and monads (part 2) https://medium.com/@xanderdeseyn/grasping-haskell-functors-applicatives-and-monads-part-2-65255e3e6a1d#.z4vc630b6
Monads, Haskell, and Elm: A Socratic Dialogue
https://medium.com/@dailydrip/monads-haskell-and-elm-a-socratic-dialogue-c0a1b4f6acb2#.tubrl9xrv
Functors, Applicatives, And Monads In Pictures
http://adit.io/posts/2013-04-17-functors,_applicatives,_and_monads_in_pictures.html