> Production code should be understandable by an on-call person at 4 am. If business logic is buried under layers of lenses, monad transformers and arrows, good

> Production code should be understandable by an on-call person at 4 am. If business logic is buried under layers of lenses, monad transformers and arrows, good luck troubleshooting it under stress. And real systems do break, no matter type safety. You can say the same thing about production Java code buried under layers of frameworks, factories, facades, proxies, aspects, annotations, etc. I don't see why readable, maintainable code can't be written as easily in Haskell as Java, C++, Python - you just have to make writing clean code a priority.