Yes. The main problem with MzScheme v4.0 and higher, and with Racket, is that cons cells were made immutable by default. This was hacked around in Arc 3.1: h

Yes. The main problem with MzScheme v4.0 and higher, and with Racket, is that cons cells were made immutable by default. This was hacked around in Arc 3.1: http://ycombinator.com/arc/arc3.1.tar http://ycombinator.com/arc/arc3.1.tar The fix is not quite perfect; occasionally it may cause problems. (Bwahaha.) Do consult the following page, which has a link to a description of a proper fix: https://sites.google.com/site/arclanguagewiki/arc-3_1/known-bugs-and-gotchas https://sites.google.com/site/arclanguagewiki/arc-3_1/known-...