splitAt is implemented in GHC in this way: splitAt n xs = (take n xs, drop n xs) So does, splitAt do double the work or is there some behind the curtain optimization? Furthermore, take and drop generate a recursive process. Why is that. After all they are library functions and beauty is not as important. Why aren't they implemented to create an iterative process?

GHC splitAt performance

splitAt is implemented in GHC in this way:

splitAt n xs  =  (take n xs, drop n xs)

So does, splitAt do double the work or is there some behind the curtain optimization?
Furthermore, take and drop generate a recursive process. Why is that. After all they are library functions and beauty is not as important. Why aren't they implemented to create an iterative process?