[thunkingdeep]

Not the person you’re respond to, but Rust is never going to have a REPL and is likely to never compile very quickly. For a lot of numerical and scientific use cases that’s a fundamentally restraining factor. WRT performance, you’re ofc correct but that’s not always as paramount as it may seem if you need to tweak the data dozens or hundreds or thousands of time. In that case, having to wait more than say 5 seconds or so is prohibitively annoying.

I think something in between Zig and Rust will emerge someday as a sort of optimal compromise between compile speed, safety, and programmability wrt memory and performance tradeoffs.

[kbarros]

Agreed. Julia's combination of REPL + JIT + Revise.jl can feel like magic. The compiler automatically detects changes to your source code and provides hot-code reloading of fully optimized machine code, in the blink of an eye!

Also, it's worth emphasizing that the user experience of Julia has been improving greatly, even in just the last 3 years. Julia 1.9 introduced caching of native code [1], and now at Julia 1.11 the time-to-first-plot in a new Julia process is typically less than a second.

Having said all this, Rust is an absolutely fantastic language too, and might be preferred for large-scale software development efforts where static analysis is prioritized over an interactive development workflow.

[1] https://julialang.org/blog/2023/04/julia-1.9-highlights/#cac...

[Imustaskforhelp]

There is a rust repl by evcxr

There was also some other if I remember correctly I saw it in the comments of https://youtu.be/eRHlFkomZJg, but now I don't see it , I think it was evcxr only.

[catgary]

It is really easy to write python bindings for Rust, which is probably the easiest way to “consume” a high-performance library (e.g. a physics simulator, data-frames, graphing, a type-checker, etc).

[xgdgsc]

Not easier than https://github.com/Suzhou-Tongyuan/jnumpy

[catgary]

Right, but Julia is just not terribly well-suited for large scale software development, which is why I’d rather use Rust.

[kennysoona]

> Julia is just not terribly well-suited for large scale software development

Why not and how so?

[kbarros]

I'll speak as someone who began as a Julia skeptic, but now finds it invaluable for my day-to-day work. Here are some reasons why you might prefer Rust today:

- Julia's lack of formal interface specification. Julia gets a lot of flexibility from its multi-method dispatch. This feature is often considered a major selling point in allowing code reuse. Many Julia packages in the ecosystem can be combined in a way that "just works". Consider, for example, combining CuArrays.jl with KrylovKit.jl to get GPU acceleration of sparse iterative solvers (https://github.com/Jutho/KrylovKit.jl/issues/15). But it's not always clear who actually "owns" such integrations. Because public interfaces aren't always well documented in Julia, things are prone to breakage, and it can sometimes feel like "action at a distance". This was especially painful with the OffsetArrys.jl package, which suddenly introduced arrays that could begin at any integer index. (That was the major theme of Yuri's blog post, and the simple solution for most people was to avoid OffsetArrays.) Rust's community philosophy and formal trait system err on the side of providing static guarantees for correctness. But these constraints also take away flexibility to fit distinct packages together. For example, Julia has always had excellent support for type specialization, and this has been notoriously challenging to fit into Rust, even in a very limited form: https://users.rust-lang.org/t/the-state-of-specialization/11.... Conversely, there have been many discussions about designing a formal interface system in Julia, but it remains a challenge: https://discourse.julialang.org/t/proposal-adding-optional-s...

- Julia is designed around just-in-time compilation. For example, every time a function is called with new argument types, it will be freshly compiled for that specialization. This is great when you care about getting optimal performance. Also, because Julia allows to reify syntax as value-level objects, you can assemble Julia code that is custom optimized to run-time values. All of this is amazingly powerful for certain kinds of number crunching codes. But carrying around a full LLVM system is clearly a blocker for distributing small, precompiled binaries. Hence the LWN discussion about the preview juliac feature, which will offer a mode for fully static compilation.

- Rust's borrow checker is something to envy. In any other language, I miss the ability to safely passing around references to stack allocated variables, or to know that a referenced value cannot be mutated.

Finally, I would probably recommend Python (not Rust!) for most machine learning or data analysis projects that aren't too "bespoke". There's just so much momentum behind PyTorch and JAX. The Julia community is developing some very interesting packages in this space. Notably, Lux.jl, Enzyme.jl, Reactant.jl, and all of SciML. These are super powerful, but still very researchy. For simple things, Python will probably be less friction.

The best language will depend on your use case. Julia serves its niche very well, even if it doesn't fit every possible use case.

[leephillips]

Can you expand on the intriguing comment that “because Julia allows to reify syntax as value-level objects, you can assemble Julia code that is custom optimized to run-time values” (ideally with an example)?

[kennysoona]

Thank you!

[pjmlp]

That isn't why it was designed for anyway, rather scientific computing.