You can horribly engineer things, regardless if you use haskell or Java.
I've seen Java code like you described, but I've also seen big java projects written in clear, no-nonsense style. For example, look at any open source Java projects released by Google.
I've also seen FP projects that require all engineers to learn category theory. Even when armed with programmers proficient in FP, project did not seem significantly more productive or less buggy from the outside. The approach-ability was lower - you couldn't just quickly glance how something works, even if you knew FP.
The most successful approaches I have seen involved adapting good functional concepts - referential transparency, immutability, compos-ability, minimising local state, functions as objects. They rarely went dogmatically all-in on pure-FP/category-theory/DSL-all-the-things. I strive to write code adhering to those rules, even in non-FP languages, but ultimately favouring practicality and I believe that I get the best of both sides.
I've seen Java code like you described, but I've also seen big java projects written in clear, no-nonsense style. For example, look at any open source Java projects released by Google.
I've also seen FP projects that require all engineers to learn category theory. Even when armed with programmers proficient in FP, project did not seem significantly more productive or less buggy from the outside. The approach-ability was lower - you couldn't just quickly glance how something works, even if you knew FP.
The most successful approaches I have seen involved adapting good functional concepts - referential transparency, immutability, compos-ability, minimising local state, functions as objects. They rarely went dogmatically all-in on pure-FP/category-theory/DSL-all-the-things. I strive to write code adhering to those rules, even in non-FP languages, but ultimately favouring practicality and I believe that I get the best of both sides.