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Comment by vinnymac | Hacker News Reader

I wonder if they are working on a time travel debugger. If it is truly deterministic presumably you could visit any point in time after a record is made and replay it.

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Exactly - that's what we've already built for web development at https://replay.io :)

I did a "Learn with Jason" show discussion that covered the concepts of Replay, how to use it, and how it works:

- https://www.learnwithjason.dev/travel-through-time-to-debug-...

Not only is the debugger itself time-traveling, but those time-travel capabilities are exposed by our backend API:

- https://static.replay.io/protocol/

Our entire debugging frontend is built on that API. We've also started to build new advanced features that leverage that API in unique ways, like our React and Redux DevTools integration and "Jump to Code" feature:

- https://blog.replay.io/how-we-rebuilt-react-devtools-with-re...

- https://blog.isquaredsoftware.com/2023/10/presentations-reac...

- https://github.com/Replayio/Protocol-Examples

No comment. :-)

Disclosure: I am a co-founder of Antithesis.

It looks amazing, nice work!

Do you have any plans to let small open source teams use the project for free? Obviously you have bills to pay and your customers are happy to do that, but I was wondering if you'd allow open source projects access to your service once a week or something.

Partly because I want to play with this and I can't see my employer or client paying for it! But also it fits neatly into "DX", the Developer Experience, i.e. making the development cycle as friction free for devs as possible. I'm DevOps with a lifelong interest in UX, so DX is something I'm excited about.

Pricing suitable for small teams, and perhaps even a free tier, is absolutely on the roadmap. We decided to build the "hard", security-obsessed version of the infrastructure first -- single-tenant, with dedicated and physically isolated hardware and networking for every customer. That means there's a bit of per-customer overhead that we have to recoup.

In the future, we will probably have a multi-tenant offering that's easier for open source projects to adopt. In the meantime, if your project is cool and would benefit from our testing, you can try to get our research team interested in using it as part of the curriculum that makes our platform smarter.

Disclosure: I'm an Antithesis co-founder.

We've actually done quite a bit of testing on open source projects as we've built this, and have discussed doing an on-going program of testing open source projects that have interested contributors. We'd probably find some interesting things and could do some write-ups. Reach out to us via our contact page or contact@antithesis.com and let's chat.

That's exactly what Tomorrow Corporation uses for their hand written game engine and compiler: https://www.youtube.com/watch?v=72y2EC5fkcE

[I work at Antithesis]

The system can certainly revisit a previous simulated moment and replay it. And we have some pretty cool things using that capability as a primitive. Check out the probability chart in the bug report linked from the demo page: https://antithesis.com/product/demo

Now I want a simulation-run replay scrubbing slider MIDI-connected to my Pioneer DJ rig to scratch through our troublesome tests as my homies push patched containers.

Seriously: impressive product revelation.

Let's do it.

That’s what rr-project does essentially?

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