Dive into the world of monad transformers in this 47-minute conference talk from Scala Days Copenhagen 2017. Explore the concept, origins, and effective usage of monad transformers through real-life examples. Learn how to make your code more readable, maintainable, and pleasant to work with. Discover the role of monad transformers in solving "effect stacking" and gain insights into alternative solutions. Navigate through topics such as category theory, functors, futures, flatmap options, and generalization. Examine practical scenarios like user management and error handling using Either types. Gain personal tips, understand potential pitfalls, and explore other related concepts like Free Monads. Be prepared for a deep dive into functional programming concepts, with a touch of humor to lighten the complexity of the subject matter.