[racket] minimum spanning tree

On 12/03/2012 06:24 AM, Pierpaolo Bernardi wrote:
> If nobody precedes me, I'll submit a proposal.

It's probably not suitable as a proposal itself, but about a year ago I 
built https://github.com/tonyg/mixfix/blob/master/graph.rkt, inspired by 
the Erlang standard graph library 
https://github.com/tonyg/mixfix/blob/master/graph.rkt.

(Looking at it again I'm really unsure why I used a hashtable instead of 
a set in a couple of places. Weird.)

Regards,
   Tony