> One problem, I believe, is that functional languages encourage more of a bottom-up approach to design Anecdotally, I tend to write Haskell "top-down", e.g. w

> One problem, I believe, is that functional languages encourage more of a bottom-up approach to design Anecdotally, I tend to write Haskell "top-down", e.g. writing QuickCheck tests for top-level functions, writing dummy definitions with `undefined`, and fleshing things out as and when the tests require it.