Wow, I really, really like that `?` operator idea. I haven't quite dived into Rust yet (I'm watching and waiting for v1.0), but I would be really excited to work with a language that makes error handing so easy and safe.
No need to wait. You can dive in right now without losing much later (I think changes between now and 1.0 aren't going to be that drastic). The guides are really good.
I have. I've learned a lot, but I just don't have any projects right now that make Haskell a great. That isn't to say I couldn't write them in Haskell, but my current projects are writing code I'm unfamiliar with, so I don't want the double whammy of struggling with the logic and structure AND learning the language.