Don't believe me? Re-read the blog post about how a major source of bugs is people making assumptions into silent errors by removing bounds checks. Simply being able to re-run the same code in a slow mode with the bounds checks turned back on would undoubtably catch bugs.
There's been a decent number of posts based around "Julia has these problems". And I don't think that's because the world at large has a vendetta; I think it's because the world at large desperately wants to use Julia, but struggle with hard blocks that are currently preventing adoption.
FWIW I do think there's a growing acceptance in the Julia community that these concerns are real, which is good. (See the parallel discussion on the Julia Discourse.)
You didn't mention speed on Lux, but it is a rewrite. The rule is that a rewrite should be assumed to be buggy until proven otherwise. A culture of having everything permanently under construction comes with upsides and downsides. And unless you have good testing, correctness problems is one of the downsides.
While, by design Enzyme is able to run very fast by operating within the compiler (see https://proceedings.neurips.cc/paper/2020/file/9332c513ef44b... for details) -- it aggressively prioritizes correctness. Of course that doesn't mean that there aren't bugs (we're only human and its a large codebase [https://github.com/EnzymeAD/Enzyme], especially if you're trying out newly-added features).
Notably, this is where the current rough edges for Julia users are -- Enzyme will throw an error saying it couldn't prove correctness, rather than running (there is a flag for "making a best guess, but that's off by default"). The exception to this is garbage collection, for which you can either run a static analysis, or stick to the "officially supported" subset of Julia that Enzyme specifies.
Incidentally, this is also where being a cross-language tool is really nice -- namely we can see edge cases/bug reports from any LLVM-based language (C/C++, Fortran, Swift, Rust, Python, Julia, etc). So far the biggest code we've handled (and verified correctness for) was O(1million) lines of LLVM from some C++ template hell.
I will also add that while I absolutely love (and will do everything I can to support) Enzyme being used throughout arbitrary Julia code: in addition to exposing a nice user-facing interface for custom rules in the Enzyme Julia bindings like Chris mentioned, some Julia-specific features (such as full garbage collection support) also need handling in Enzyme.jl, before Enzyme can be considered an "all Julia AD" framework. We are of course working on all of these things (and the more the merrier), but there's only a finite amount of time in the day. [^]
[^] Incidentally, this is in contrast to say C++/Fortran/Swift/etc, where Enzyme has much closer to whole-language coverage than Julia -- this isn't anything against GC/Julia/etc, but we just have things on our todo list.
[ps sorry if this ended up as a dup, I meant to reply deeper in the tree, so I deleted the older comment and moved it here].
But I maintain my position. If users are choosing packages because of speed without worrying about correctness, then packages will become popular that care less about correctness than what you describe. And when people combine popular packages that make conflicting assumptions, correctness will be lost.
In other words the problem is the attitude, not the specific package. For another example of the same problem, look at how C/C++ compilers prioritizing speed has resulted in their taking advantage of undefined behavior in a way that makes it far harder for any significant C/C++ codebase to be correct.
Running Julia with the command line argument --check-bounds=yes does that, and package testing always uses this option to disable inbounds.
With my programmer hat, the first thing I care is not speed for most cases. Unless there's an explicit need for speed, I don't select the language I gonna use with respect to its performance, and I don't port a tool unless the speed becomes limiting.
It's important to make it run first, then make it fast. Otherwise, things go very wrong, very fast (pun intended).
