This is very impressive and cool. However I really don't think that parsing source code and manipulating is a very maintainable way to do this (and this as someone who writes Clojure for a living).
You could do exactly the same using very simple Knockout. It wouldn't be as funky, but it would be something you'd be happy to use in production.
I did something like this in my presentation[1] about Ember.
It uses Ember.js to maintain the state of the code samples and proved to be very stable. I don't have interactive sliders on specific values, but the code is parsed and run after every character the user types. e.g. you can change the size of the squid on this page[2] and see it reflected immediately on the right.
It isn't really intended for production use. Personally, I plan to use it to tweak values in games I write, because having to alt+tab, find, edit, alt+tab, refresh, restore state for every tiny tweak to the position of a UI element sucks.
You could do exactly the same using very simple Knockout. It wouldn't be as funky, but it would be something you'd be happy to use in production.