Well, frankly you can get along not knowing the "Gang of Four" design patterns and write Java. By the same token, you don't need to know about iterables and comprehensions to write Python, smart pointers to write C++, Graph theory to use a Graph database, macros to write LISP, etc.
By analogy, you don't need to know abstract algebra and category theory to write Haskell. But as in the other cases, knowing helps.
By analogy, you don't need to know abstract algebra and category theory to write Haskell. But as in the other cases, knowing helps.