[racket] Typed Racket Predicate Generation Regression?

On 10/30/2012 05:25 PM, Neil Toronto wrote:
> Obviously, the type of `n' is Integer. But what can its runtime value
> be? What if there were a parallel thread changing its contents? What if,
> in the first "...", you called a thunk with `bx' in its closure that
> happened to change its contents to (list 4)?

How interesting to consider that and the idea of Software Transactional 
Memory at the same time!

(atomic
   (cond [(boxof-integer? bx)
          (define n (unbox bx))
          ...]
         [else
          ...]))

Cheers,
   Tony