Hi Peter - yes of course you are right that its malleable, I guess I���m often suprised about the things we leave out and then discover weird things we���ve put in.
I had a quick look at LinkedList (I should have thought of that) - I might be able to do something with that (and this is now more out of curiosity) - but gosh its an easy way to crash your image. Having linked the first to the last, and then tried a quick: list after: $n - I���m now guessing I���m stuck in an infinite loop that even Cmd . won���t break out of!!!! ouch.
If you look at Hier(archy) of LinkList you'll see Semaphore underneath it.
I'm not sure, but there may be some VM magic around Semaphore and Process management that makes it fragile to changes.
I believe there have been some proposals to separate out the Process related LinkedList stuff, but I can't remember the exact arguments.