[evilotto]

The talk about immutabilty and serialization makes me think of tcl, where "everything is a string" also means "everything is serializable" and you don't copy references around, you copy strings around, which are immutable. What's neat is that it always looks like you are just copying things, but you can mutate them, just so long as you can't possibly tell that you have mutated them, meaning that the old value isn't visible from anywhere. With the caveat that sometimes you have to jump through hoops to mutate something.