It is indeed a weird language. I've been rusting heavily for about a week (doing Matasano crypto challenges) and I'm still puzzled at lifetime errors.

Managing lifetimes is hard to reason about (though this is not a problem with Rust, but with lifetimes... Rust just makes it explicit.)

As soon as you start using generics things can quickly get out of control. Here's one of my function signatures:

    pub fn xor_together<'a, 'b, 'r, A, B, R, T, U>(iter_a: T, iter_b: U) -> Map<'r, (&'a A, &'b B), R, Zip<T, U>>
        where A: BitXor<B, R>,
              T: Iterator<&'a A>,
              U: Iterator<&'b B>

If you get those lifetimes wrong, the error propagates and you end up having lifetime errors farther in your call chain, which are quite hard to debug. I'm not even sure those lifetimes are 100% right.

Some other weird things include closures. There are several types of closures, not interchangeable with each other (nor with fn) and honestly I don't understand them (and couldn't find docs to explain them). I hope this changes as Rust stabilizes.

I'm loving it so far, but boy... how hard it is.