Racket is a Scheme variant and Dr Scheme, now Dr Racket, is a kind of interactive development environment similar to the above ones.

However when I talk about Lisp I seldom think of Scheme, due to their differences, in spite of the common parentheses.

I've barely used Dr Racket and even then it's been years so I might be misremembering, but I don't think it comes with any hot swap capabilities (the main point of this demo) out of the box, even though it had a REPL.

Yeah I was about to say, I can't think of any Scheme implementations or descendents with robust support for hot swapping.

The current transition to Chez Scheme might allow this in the future.