clasp VS rr

I accidentally a Common Lisp that interoperates with C++ (https://github.com/clasp-developers/clasp.git). We would also like to move beyond BDWGC and Whiffle looks interesting. I will reach out to you and maybe we can chat about it.

Clasp might be such a language, it seems.

https://github.com/clasp-developers/clasp

/u/jeaye are you aware of CLASP? https://github.com/clasp-developers/clasp https://www.youtube.com/watch?v=mbdXeRBbgDM

Sounds to me like CLASP; it automatically exports C++ objects to be used from Common Lisp also via llvm.

Now, the difference of compiling speed of SBCL and CCL is not so big. Look at cl-benchmark, LispWorks is really fast, CCL is on par with Allegro, SBCL is close to CCL. Or https://github.com/clasp-developers/clasp/wiki/Relative-Compile-Performance-of-clasp, it depends on specific project (SBCL sometimes faster, slower, alike), overall difference is not big.

So..

"Why do you want to make Lisp more popular? If you were sucessful, what would be different in the world, and why is that desirable to you?"

Normally at this point I'd listen to the response, and ask more questions based on that. That would wind up with a very, very deep thread, so I'll break a cardinal rule and pre-guess at some answers.

This kind of question comes up pretty frequently. In many cases, I suspect the motivation behind the question is "Wow! Here's this cool tool I've discovered. I want to make something really useful with it. I want to do it as part of a community effort; share my excitement with others, share in their excitement, and know that what I'm making is useful because others find it desirable and are excited by it." The field could be cooking, sports, old machine tools, tiny homes, or demo scene. Its the fundemental driver for most content on HN, YouTube, Instructables, and such. It is a Good Thing.

If that is your motivator, then my suggestion is to find something that bugs you and fix it. You've already decided you're only interested in code, not other aspects. You said you preferred vim, but the emacs ecosystem has a very rich set of sharp edges that need filing off, and a rich set of tools with which to attack them.

One example: even after 50 years there's no open IDE which allows you to easily globally rename a Lisp identifier. I don't know about LispWorks or other proprietary environments, but you can't in emacs or vim do a right-click on "foo" in "(defun foo ()...)" and select a command which automatically renames it in all invocations. [Queue lots of "but you can..." replies here.] I don't think vim is up to the task of doing this internally. It would be possible in emacs; but would require a huge effort with lots of help from other people. If you emerged alive from that rabbit warren you'd join the company of Certified "How Hard Could it Be?" Mad Scientists such as Dr. "I just want to draw molecules" Meister [1] and "Wouldn't an OS in Lisp be Cool" Froggey [2].

[1] https://github.com/clasp-developers/clasp

[2] Mezzano https://github.com/froggey/Mezzano

But also, there's a reason why most implementations readily make an effort to provide interoperability tools with a variety of runtimes. Clasp much like ABCL gives access to a whole library of other libraries trivially wrapped to interoperate with at little to no performance to cost (depending on how thin you make the wrappers, mainly).

I think this tool must share a lot techniques and use cases with rr. I wonder how it compares in various aspects.

https://rr-project.org/

rr "sells" as a "reversible debugger", but it obviously needs the determinism for its record and replay to work, and AFAIK it employs similar techniques regarding system call interception and serializing on a single CPU. The reversible debugger aspect is built on periodic snapshotting on top of it and replaying from those snapshots, AFAIK. They package it in a gdb compatible interface.

Hermit also lists record/replay as a motivation, although it doesn't list reversible debugging in general.

Interesting. Perhaps you can inspect the disassembly of the function in question when using Graal and HotSpot. It is likely related to that.

Another debugging technique we use for heisenbugs is to see if `rr` [1] can reproduce it. If it can then that's great as it allows you to go back in time to debug what may have caused the bug. But `rr` is often not great for concurrency bugs since it emulates a single-core machine. Though debugging a VM is generally a nightmare. What we desperately need is a debugger that can debug both the VM and the language running on top of it. Usually it's one or the other.

> In general I’d argue you haven’t fixed a bug unless you understand why it happened and why your fix worked, which makes this frustrating, since every indication is that the bug exists within proprietary code that is out of my reach.

Were you using Oracle GraalVM? GraalVM community edition is open source, so maybe it's worth checking if it is reproducible in that.

[1]: https://github.com/rr-debugger/rr

https://rr-project.org/ had the same problem. They use the retired conditional branch counter instead of instruction counter, and then instruction steeping until at the correct address.

That'll work great for your Distributed QSort Incorporated startup, where the only product is a sorting algorithm.

Formal software verification is very useful. But what can be usefully formalized is rather limited, and what can be formalized correctly in practice is even more limited. That means you need to restrict your scope to something sane and useful. As a result, in the real world running thousands of tests is practically useful. (Well, it depends on what those tests are; it's easy to write 1000s of tests that either test the same thing, or only test the things that will pass and not the things that would fail.) They are especially useful if running in a mode where the unexpected happens often, as it sounds like this system can do. (It's reminiscent of rr's chaos mode -- https://rr-project.org/ linking to https://robert.ocallahan.org/2016/02/introducing-rr-chaos-mo... )

The approach of check-pointing computation such that it is resumable and restartable sounds similar to a time-traveling debugger, like rr or WinDbg:

https://rr-project.org/

https://learn.microsoft.com/windows-hardware/drivers/debugge...

https://github.com/rr-debugger/rr?tab=readme-ov-file#system-...