[plt-scheme] Writing a kill-safe data structure

Hi everyone,


I was wondering if someone could give a look at some code I've written to 
maintain a "topological queue".  I've tried to write it to be kill-safe 
according to the techniques in the "Kill Safe Synchronization 
Abstractions" paper by Flatt and Findler.  The code is here:

     http://hashcollision.org/tmp/topological-queue.ss

Is it kill-safe?


I'll eventually put it on PLaneT, as soon as my project I'm using it for 
is finished.  Any code comments would be greatly appreciated.  Thanks!