Haskell is fantastic. In fact, it is by far my favorite language. Strict types and functional programming come together in a perfect union. Monads are very similar to JavaScript callbacks, actually. After extensive use of the language, I finally decided to give it up for 2 reasons. 1) Stack and package management. Specifically, after building many websites with Haskell's "supposedly" production ready framework, Yesod. After an upgrade, every site I made completely broke and there was almost no documentation on any version changes for this framework. Which leads me into complaint 2) Lack of good documentation. I'm not trying to take sides on the debate of self documenting code, however, when using higher level libraries, it is completely infeasible to rely on reading source code to determine what a function does. Haskell programmers believe that because of such strict typing, the code should speak for itself. Unfortunately, the real side effect of this is you end up coding trying to match up your types instead of focusing on your goal at hand.