There's a difference between empty strings and Null values imo.

Just "" != Nothing

If you want to handle empty strings as a input in haskell then you have a function of type `f :: String -> b` and you pattern match on your input?

  f "" = someResult
  f ...

Nothing assumes a proper null in that there is genuinely nothing to work with. Still you can make a function to handle it or use `maybe`?