Lecture demistifying monads. After talking a bit about Monoids and Functor I explain a functional design technics which is Monad through the refactoring of a JDBC code. Talk given at The Developper Conference in Porto Alegre in 2014 (http://www.thedevelopersconference.com.br), Code source of the presentation is in my github: https://github.com/toff63/monads-in-practice-tdc