[monokrome]

What do you mean, "finally implemented"? I thought that Bret Victor himself was doing it using his own Tangle.JS library?

http://worrydream.com/Tangle/

[Lutin]

I believe they meant finally implemented in Elm. The title has since been changed to clarify.

[lgas]

Also, for what it's worth, Tangle is more of a DOM/UI binding library that you might use to build something like Elm's debugger into your own JS app.