The whole discussion started from the claim that Haskell makes the NullPointerException/NoneType non existent. And I am just saying it isn't any different from how you enforce it in any other language - you either handle nulls or throw exceptions.
> (so throwing an exception is wrong)
I am sorry, but I don't play the "throwing an exception is wrong" game. I use it for actual exceptions, control flow, must-handle scenarios. I don't see how exceptions are defined has to do with how I use it if it makes my program logic clear or translates to my intent. The only reason I think before using exceptions for things which aren't exceptions is the stack which is saved, which most of the times so minuscule that it doesn't matter. Ruby has the best compromise as in it defines catch..throw; most of the languages don't so I resort to using exceptions.