[racket] Doing collision detection in universe.ss

Shriram wrote:

> Yaron, this summer my students, Kathi Fisler, and I built a block-based,
> functional language with types (expressed as colors) and testing. It runs
> in the browser, uses the WeScheme runtime and can express most Bootstrap
> programs.
>
> It needs more polish before we can release it to the world. We would be
> happy to give previews to anyone who wants to see them.

If this is DrBlocket, then Danny Yoo gave a 10-minute talk on it at 
RacketCon this October; slides and video are here:

http://con.racket-lang.org

--PR