In theory that's true, and I hope Scala eventually makes non-null, immutability and perhaps even I/O visible at the type level. In practice as long as it's clear when you are bypassing these systems, and you have a culture of not doing so (and the language libraries are part of the same culture), you get most of the benefits.

Even in Haskell you can cast out of your type system, or unsafePerformIO, no?