[Haskell-cafe] Is it possible to make lazy combinators for IO?

If f :: a -> IO a for some a, and I want to use mfix f then f must not inspect its argument in any way, or the computation will get stuck. In some cases, this seems a bit harsh. For example, mfix (\x -> fmap (3 :) (x `seq` readLn)) looks perfectly reasonable. There is no need to inspect the return [] action to know that the final result of the computation will begin with 3:. Is there a lazy IO mapping function somewhere that can work such magic?