Do you disagree with that assertion? Or are you just saying that the syntax change as I propose it is called "effect analysis"?

Sorry, I thought you were talking about the usability of IO and State monads in particular, not more general ones. When I was talking about effect analysis it was along the same lines as how (fun1 :: a -> IO b) and (fun2 :: a -{IO}> b) are basically equivalent - though IMHO fun2 can be easier to use because it's type is a bit more orthognal to a "pure" function (fun3 :: a -> b). Ben.