[racket] Read-only parameters

From: Danny Yoo (dyoo at hashcollision.org)
Date: Mon Feb 11 18:25:37 EST 2013

> Perhaps you can use contracts to enforce this?

Oh, wait: I didn't pay attention to the error message at all.  My
apologies!  So nope, my approach doesn't work here...  I'll think
about this some more.

Posted on the users mailing list.