[kbelder]

Forth behaves the same way. The vocabulary is really a stack, and you can define words, redefine them, and then pop them back off to return to the old value.

It's really not useful for variables, but can be very useful for functions, and since they're pretty much the same thing, you get the behavior for free. Although I haven't touched Lisp, my understanding is that Forth and Lisp have some conceptual similarities, but Forth is written by an engineer and Lisp by a computer scientist. Limit you for your own safety? Not a thing in Forth.