“Haskell’s type system really does ensure a higher degree of consistency compared with many mainstream languages. In my experience, bugs in dynamically typed languages are often “silly” mistakes from refactoring: I changed an object field property, but didn’t update all the places it was used. In Haskell, the compiler tells you what you missed, because your change altered the type of the object and now there’s a mismatch between that and what the old usage assumed.

The language also encourages you to program in a style that has strong static guarantees. For example, you could store your configuration in a dictionary from string to string, and then handle missing or invalid entries wherever you use the configuration. It is usually easier however, to specify the configuration type in detail; you state that it MUST have a port that’s an integer for example. You can then rely on that everywhere – you know that port lookup can’t fail. Reading the configuration from disk can of course fail and you might choose to handle that by exiting the program or supplying a default value.”

See: https://www.infoq.com/news/2016/08/haskell-production-retrospective