Interesting. I knew VS had been working toward features like that; I wasn't aware they'd come as far as they have. Though from my poking around there appear to be some limitations: no redefining lambdas in a live session, for example. And I'm pretty sure that Instaparse is still out of reach, though that's not really what was being referred to. But thank you for reminding me, it's been a while since I've had an occasion to touch VS.