First off, I'm not sure it's even worth it to understand this stuff... Second, someone should be along to slam it soon enough and insist I've missed some gibberishy business that you'll never understand.
With those caveats in mind, here's a more intensive scala-based monad tutorial I made:
But really, don't burn up too much of your short life trying to come to terms with this stuff. There's a reason most languages don't get around to supporting Monads...
It' really worth understanding. I studies Haskell and Scala to write better Python, Typescript, and Java, and it did help.
The whole thing about JS's Promises becomes way clearer when you see that they are a monad, except for one discrepancy (they auto-flatten themselves). It leads to much shorter and clearer code when doing pedestrian frontend stuff.
With those caveats in mind, here's a more intensive scala-based monad tutorial I made:
https://github.com/zaboople/techknow/blob/master/scala/monad...
But really, don't burn up too much of your short life trying to come to terms with this stuff. There's a reason most languages don't get around to supporting Monads...