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Comment by omphalos | Hacker News Reader

One improvement that this has over most of the "conventional" reversible debuggers mentioned in the comments is the ability to instantly see the effect of your change over time. For example, with Mario example, after jumping up and down, you can adjust the gravity parameter to see what paths Mario would have taken with different gravities and the same input stream.

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I'm loathe to say with confidence, but you're right, that does seem to be a relatively novel contribution. It's certainly unusual!

I spent some time reading Hewitt's PLANNER paper recently. I am tempted to think that something drawing from his ideas on hypothetical explorations could be implemented for debugging (more than just numerical adjustments). But it's been a while since I reviewed the debugging literature to say with confidence if such a thing once existed.

Strobing and scrubbing, retroactive update have been done since the 70s. The problem has been scaling up beyond toys.

I'm not familiar with the strobing/scrubbing terminology. I don't think my memories have decayed that badly. :-) I don't suppose you have a paper you'd mind linking to about this?

It is terminology that the live coding and live programming communities (well, at least Alex McLean and myself) are just adopting, and related to analogous capabilities in tools for video editing (like FinalCut Pro, AfterEffects). The terminology is meant to help us describe older work and the newer experiences like those illustrated by Bret Victor.

I use these terms a bit in my recent papers, but I don't go into much detail:

http://research.microsoft.com/apps/pubs/default.aspx?id=2112...

http://research.microsoft.com/apps/pubs/default.aspx?id=1898...

For the first paper, here is an annotated video that perhaps shows it better:

http://youtu.be/xmWJsTTOvkU

You would be correct in thinking they are hardly standard. Time travel is such a sexy term alternative that most people just use that, even if it isn't very descriptive.

Programming with Managed Time takes an fairly novel approach to the semantics of time. I can't say that I've ever really run into a system very much like that before (my MS was on distributed debugging and I did a fairly deep dive into the history and literature).

Anyway, the strobe/scrub terminology I think is worth using, IMO. It describes it well. Time travel is pretty fun to say though. =)

ah well, it inspires me to continue on with my research. :-)

Nice that you like it. We will try to promote it more later with a web essay, many people on HN don't like reading academic papers. Good luck with your research, I'm also involved in some similar distributed systems work (I'm a PL researcher who works in a systems group).

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