Julia 1.12 highlights (julialang.org)

We use it for binary deployments via building simulations into the FMI standard (i.e. building FMUs) https://fmi-standard.org/. We still need to get libraries updated for getting the smallest possible trim when using the more computationally difficult implicit methods, but at least the stack is matured for simple methods like explicit RK and Rosenbrock-type solvers already. For folks interested in --trim on SciML, the PR to watch is https://github.com/SciML/NonlinearSolve.jl/pull/665 which is currently held up by https://github.com/SciML/SciMLBase.jl/pull/1074 which is the last remaining nugget to get the vast majority of the SciML solver set trimming well. So hopefully very soon for anyone interested in this part of the world. Note that does not include inverse problems in the binary as part of small trim.

But all of this is more about maturing the ecosystem to be more amenable to static compilation and analysis. The whole SciML stack had an initiative starting at the beginning of this summer to add JET.jl testing for type inference everywhere and enforcing this to pass as part of standard unit tests, and using AllocCheck.jl for static allocation-free testing of inner solver loops. With this we have been growing the surface of tools that have static and real-time guarantees. Not done yet, some had to be marked as `@test_broken` for having some branch that can allocate if condition number hits a numerical fallback and such, but generally it's getting locked down. Think of it as "prototype in Julia, deploy in Rust", except instead of re-writing into Rust we're just locking down the behavior with incrementally enforcing the package internals to satisfy more and more static guarantees.

for many types of scientific computing, there's a case to be made it is the best language available. often this type of computing would be in scientific/engineering organizations and not in most software companies. this is its best niche, an important one, but not visible to people with SWE jobs making most software.

it can be used for deep learning but you probably shouldn't, currently, except as a small piece of a large problem where you want Julia for other reasons (e.g. scientific machine learning). They do keep improving this and it will probably be great eventually.

i don't know what the experience is like using it for traditional data science tasks. the plotting libraries are actually pretty nicely designed and no longer have horrible compilation delays.

people who like type systems tend to dislike Julia's type system.

they still have the problem of important packages being maintained by PhD students who graduate and disappear.

as a language it promises a lot and mostly delivers, but those compromises where it can't deliver can be really frustrating. this also produces a social dynamic of disillusioned former true believers.

In my experience starting with Julia in 2025, the main thing missing from the ecosystem tends to be boring glue type packages, like a production grade gRPC client/server. I heard HTTP.jl is also slow, but I havn't sufficiently dug into this myself. At least we have an excellent ProtoBuf implementation so you can roll your own performant RPC protocol.

As for the actual numerical stuff I tend to roll my own implementations of most algorithms to better control relevant tradeoffs. There are sometimes issues where a particular algorithm is implemented by a Julia package, but has performance issues / bugs in edge cases. For example, in my testing I wasn't able to get ImageContrastAdjustment CLAHE to run very fast and it had an issue where it throws an exception with an image of all zeros. You also can't easily call the OpenCV version as CLAHE is implemented in OpenCV using an object which doesn't have a binding available in Julia. After not getting anywhere within the ecosystem I just wrote my own optimized CLAHE implementation in Julia which I'm very happy with, this is truly where Julia shines. It's worth noting however that there are many excellent packages to build on such as InterprocessCommunication, ResumableFunctions, StaticArrays, ThreadPinning, Makie, and more. If you don't mind filling in some gaps here and there its completely serviceable.

As for the core language and runtime we are deploying a Julia service to production next release and haven't had any stability/GC/runtime issues after a fairly extensive testing period. All of the Python code we replaced led to a ~40% speedup while improvements to numerical precision led to measurably improved predictions. Development with Revise takes some getting used to but once you get familiar with it you will miss it in other languages. All in all it feels like the language is in a good place currently and is only getting better. I'd like to eventually contribute back to help with some of the ecosystem gaps that impacted me.

Waiting 15+ seconds to test small changes to my PyTorch training code on NFS is rather annoying. I know there are ways to work around it, but sometimes I wish we could have a training workflow similar to how Revise works. Make changes to the code, Revise patches it, then run it via a REPL on the main node. Not sure if Revise actually works in a distributed context, but that would be amazing if it did. No need to start/fork a million new Python processes every single time.

Of course I would also rather be doing all of the above in Julia instead of Python ;)

BOLT isn't on by default. The main problem is that no one has tested it much (because you can only get it by building your own Julia). We should try distributing BOLT by default. It should just work...