Destructors seem to be a 
   pain point 

The problem is not so much typing as such (things that don't return anything but terminate -- as destructors do -- can be typed as Unit) but rather to find a good trade-off between expressivity of the language and simplicity of the typing system.

Basically explicit destructors mean the typing system needs to track lifetimes and ownership in some form or shape. There seem to be two main options.

- Simple lifetime/ownership scheme, but then you need a garbage collector anyway, and that it's mostly pointless to have explicit destructors. Just let every variable be cleaned up by the GC makes for a simpler language (under the hood clever escape analysis might be used for stack allocation of variables that don't escape their activation context).

- Avoid a GC, but then you need a complex typing system with unique owners to have any chance at expressivity (and you still need unsafe blocks and reference counting). This is Rust's choice.

Another issue is how consistently to combine destructors with other effects, in particular exceptions.

   Pointer/backpointer pairs 
   need to be a language level 
   concept.

As "JoshTriplett" also suggests, this is certainly an interesting idea, but I don't think a compelling choice has been found yet.