Cool stuff. I was a bit confused by why the "if (worth < 1000000)" condition line wasn't highlighted for each iteration (though it clearly was executed). Is that a little bug or am I misunderstanding the presentation?<p>Did you watch Bret Victor's talk "Inventing on Principle"? The step-through feedback and stack/heap display of your app reminds me of the javascript tools he shows in that video.<p>I'm going to be going through your examples now. Thanks!