Hrvoje> BTW, why do we want Lisp-level readonly objects in the first place? The most obvious is that, with the right dumper and OS support, you can put them in shareable/read-only/EPROM memory. Another is that you can optimize GC with this kind of knowledge. It seems that, since reachability is affected by mutable plists, you want the plists of immutable objects to be immutable as well. Hrvoje> Do other Lisp flavors (such as CL) have them? Scheme has. I've written a portable dumper for Scheme 48 which exploits this, as well, with noticeable gains in efficiency. I'm pretty sure CL has, too. -- Cheers =8-} Chipsy Friede, Völkerverständigung und überhaupt blabla