Comment by danidiaz

Those articles (and the videos https://www.youtube.com/watch?v=I8LbkfSSR58&list=PLbgaMIhjbm...) are great but one doesn't need to learn category theory to understand monads in Haskell.

The Haskell Wikibook is an underrated resource: https://en.wikibooks.org/wiki/Haskell/Understanding_monads