[racket] #<undefined> and backward compatibility

On 04/18/2014 09:00 AM, Matthias Felleisen wrote:
>
> On Apr 18, 2014, at 10:48 AM, Neil Toronto <neil.toronto at gmail.com> wrote:
>
>> Another benefit is that Typed Racket will no longer have to consider non-function letrec bindings as having the type (U Undefined A) where A is the "real" type. (Technically, (U Undefined A) *was* the real type.)
>
>
> That was my primary motivation for launching this project, motivated by nearly two decades of coping with such unions or a lack of safety. I knew you'd appreciate it -- Matthias

Aww!

I checked the Northeastern publications page and didn't find anything on 
this. Is there somewhere I can read about the sorcery that accomplishes it?

Neil ⊥