It's written by a Julia fan, so it's a very lucid and measured take on the not so great side of Julia.
I completely agree with Jakob's take in the piece you've shared btw. Personally, I don't think Jakob goes far enough.
I've used Julia professionally too, and worked with large code bases (a 10000 line Julia monorepo project that just keeps growing), and the lack of interfaces, the lack static type checking, the lack of error types, etc would all be show stoppers for me to consider Julia at the start of our project if I knew then what I know now. I've even tried to run static type checkers like JET.jl on our code base and it just keeps spinning or failing. Unfortunately it is a sunk cost for us at this point and we'll just have to use Julia, and deal with these pain points, and hope and pray the language gets better over time.
I can see some improvements such as minor latency improvements happening over time. But (in my opinion) I don't think language features like interfaces are likely to happen until Julia 2.0. In 2018, the core team had laid out priorities in a discourse post, and marked those as done last year (i.e. 2021).
https://discourse.julialang.org/t/compiler-work-priorities/1...
In my opinion, there's a LOT more language features required to help tooling in the ecosystem improve. The fact that they marked this as done (which I just found out while typing this comment) and that there's no follow up priorities outline post (as far as I can find) is a little troubling.
I think a lot of people that pick Julia as their first language really like it, but I believe it is mainly because they haven't experienced something better to compare it to. I'm not saying everyone is this way, and obviously everyone values different things in their programming language / development environment. I do think if you don't know what's out there you tend to just accept that something you are doing is the norm.
And I think a lot of people that come to Julia from languages like Python, R, C++ see value in Julia for solving package development issues (compared to python), better language design (compared to R), performance without verbosity (compared to C++). And I think they weight those issues more heavily than I do. I've dealt with Python packaging issues, and still do on a daily basis but I now know my way around whatever comes up. R's syntax might be kludgy but I'm damn productive if I'm using ggplot. I'd rather use Python for general purpose work and R for plotting, than having to deal with Julia. C++ though I'd never want to touch again, and would just use rust instead. If rust wasn't an option, I think I'd end up using Julia (even though I complain about it so much). This is just were my priorities / skill level lies, and I can completely see how it would be different for others.
I'm much more productive plotting in Python and R than I am in Julia, purely because of compile times, even though Julia has a much better designed plotting package than Python (R's plotting ecosystem is rather convenient even if it is counter intuitive some times).
When you've used Rust, Go, Nim etc, developing in Julia feels so ... antiquated. Just as one example, when using Rust, you can write a unit test function right next to the function you are testing. And you can run just that unit test function from a terminal (e.g. `cargo test -- test_just_this_one_function`). And because you can write a quick little test function pretty much anywhere in your code and run it in the terminal, you don't really feel the need for a REPL all that much. When I'm not writing tests, I would say I'm as productive in Rust as I am in Julia (mainly because of awesome language server features in Rust). But the moment I need to write tests in Julia ... it's a big oof y'all.
In Julia there's NO official way to run just one test. You HAVE to run all of them. And the tests can be scattered in various different tests files in the test folder. Try contributing to the core Julia language itself, and trying running their test suite. You'll have to go get coffee multiple times just to make one single patch.
For projects that I'm working on, I literally have a Julia REPL open with Revise, where I manually include a specific test file after commenting out unnecessarily global state, and then call a the function I want to test that way. It's madness, and I _think_ this is what everyone does (?). If people are saying they prefer this, I can't help but liken it to Stockholm syndrome or something to that effect.
Even more than Rust or Go, I think Julia could take a page from Typescript in terms of tooling because JS is so dynamic and the tooling is so nice.
I do think compiler latency has gotten way better in more recent versions of Julia, but I think better ahead of time compilation, faster interpretation, and code caching are all important.
I think Julia's tooling used to be better in Atom (Juno), however, Atom is dead.
Aside from interfaces, what would those be?
* Better language level support for testing
* Better language level support for docstrings - currently doc strings are just normal strings stored in a global struct, and are missing crucial information about the type signature of structs or functions or methods that are being documented
* A way to type hint without using multiple dispatch / interfaces - I want to be able to say this argument has fields x, y, z but I don’t want to use multiple dispatch to enforce this interface. Multiple dispatch is useful with the implementation details of your code depend on the data structure. But I want better static type checking for a handful of fields or methods. Typescript is absolutely awesome at this.
* Support for using @copied s.x = 1 where s is an immutable struct. Users are literally incentivized to use mutable structs instead of immutable structs because that results in shorter cleaner syntax, even though performance drops through the roof in that case. With immutable structs you’ll have to recreate the struct by calling the constructor. In most cases, the compiler will compile as this away anyway but users are going to prefer shorter cleaner syntax when writing code.
* Better macro support. Currently macros have to be valid Julia code, meaning you end up with weird dsl that only kind of sort of matches the domain being modeled. In rust and nim I can literally copy almost any syntax and paste it in a macro block and it’ll just work. This is more work for macro developers and probably will make inference harder but will improve readability.
* Language level support for extending Array or letting users define arrays that are as efficient as the built in ones.
* Similar request for String buffers.
* Rewrite parser that is currently in scheme in Julia, I suspect better tooling will fall out of this
* Support for a subset of Julia that is fast to compile and run and produces small binaries.
I think more generally I want Julia to be a slightly different language than it is ( or possibly ever can be ). Currently a user of Julia needs to be cognizant of too many things that could accidentally introduce type instability. Almost none of these problems are going to be encountered by someone that understands how compilers work / how computers work, which in my experience is not a lot of domain scientists but is a lot of the core team working on Julia. Domain scientists have PhDs or Masters in highly niche subjects after years of writing Python, R, or Matlab but are more often than not terrible software engineers. I can’t tell how many times in almost a decade of being in this field have I seen 10,000 line scripts in a single file without any comments written by extremely smart scientists. Guiding these folk from the get go to make better software engineering decisions is important imo. Currently, if I’m leading a project, I can’t trust a fresh graduate or junior engineer to write idiomatic type stable fast and extensible Julia code, even if they are the experts of their domain. They have to be experts of their domain AND awesome software engineers which is so rare to find. Given additional constraints about funding, writing proposals, documentation etc, it’s honestly kind of amazing that Julia’s libraries are as good as they are.
In my opinion, Julia really shines when one or two people have to write code to tackle a specific problem. Code is super concise and clean and it all fits in your head and everything is fine and dandy. But when you have an engineering team that needs to work with databases, authentication, logging, deployment, scaling, machine learning, data analysis and plotting, and do most if not all of that in Julia … it’s so easy to write something that gets checked in that passes tests and code review that just destroys performance benchmarks.
I feel like the ideal language would combine the strengths of Rust (static type checking, great LSP, better threading, better package manager, easy compilation without a large runtime, etc.) with the focus on the scientific computing domain and all the associated trade-offs that Julia has. Maybe it's not possible to have the best of both worlds, but it sure would be nice.
* Support for using @copied s.x = 1 where s is an immutable struct.
I believe the standard package for this is this:
https://github.com/jw3126/Setfield.jl#usage
* Currently macros have to be valid Julia code,
There are two kinds of macros, and it sounds like you want `macro foo_str(x)` which accepts anything. But the tradeoff is that you have to parse it, rather than getting an expression tree.
https://docs.julialang.org/en/v1/manual/metaprogramming/#met...
* Similar request for String buffers.
* Rewrite parser that is currently in scheme in Julia, I suspect better tooling will fall out of this
These 3 are all desired and totally doable. They just need some developer time. If anyone wants to help on them, get in touch.
I'd really love a PackageCompiler that would "just work" though. Julia 1.6+ made a lot of progress in pre-compile times. However, nothing beats being able to easily release a binary...
We're a very Spark-heavy shop so I've tried to encourage Scala, but that got no traction, and it would raise its own set of problems. I like Rust but it's simply too complex to expect scientists and data scientists to wrap their heads around; it's hard enough to get them to use Python type hints.
Oh well.
Wrt. static type checking, JET.jl does the job for me. I agree it still feels too immature with slowness and important edge cases it fails to consider. More importantly, the ecosystem itself needs to fully embrace type stability for it to be optimally useful, since otherwise you will get a shitton of false positives from functioning, yet unstable dependencies. The good news is that all of these things are improving quickly for JET.jl - it's getting faster and more robust. It still feeds immature since it's actively being developed.
There is also the linter, which is available in VSCode. It's pretty good. Nowhere near the level of rust-analyzer, but still decent.
You can easily have error types in Julia - see the package ErrorTypes.jl. It's not standard to use it, but I use it in my work code, and it works quite well.
You can absolutely write tests next to code and just run one test - see InlineTests.jl and ReTest.jl
HOWEVER:
* The latency is still terrible, and it really, _really_ hinders development. I don't see that being significantly solved in the next many years, only marginally improved. This can reasonably be a showstopper for some people. You learn tribal knowledge to lessen its blow (wrap things in modules, use Revise etc), but there is no sugarcoating it: It blows.
* The lack of statically enforceable interfaces is a real problem, and I think this will NEVER be solved in Julia. There just doesn't seem to be any real motivation from the core team, and no agreement in the community on what such a solution even should look like.
* The lack of separation of tests is very annoying as well. That might literally be impossible in Julia since part of its promise is that you can dynamically change definitions that affect other modules. It's what contributes to its great composability. But it also means you need to test ALL of Base if you change one thing.
When JET.jl works it is great. But for large projects it didn't even return when I tried it. I must have waited at least half an hour once.
VSCode seems like it is offically blessed and maybe I should just cave and use it for Julia. I use vim/neovim for EVERYTHING else though. Taking me out of my extremely custom tmux + terminal + vim workflow just for Julia development annoys me unnecessarily much. Do you know if there's work on getting this to work in vim/neovim?
ErrorTypes.jl, InlineTests.jl, ReTest.jl, SetField.jl all are awesome and I've used them in personal projects. I want to see them in the core language. Maybe ErrorTypes.jl is asking for too much, but tests sorely needs improvement. A SetField like feature literally had a PR open for years and then was just closed
https://github.com/JuliaLang/julia/pull/21912
Without these features in the base language, adoption is going to be so slow. Convincing my team to add a dependency is a lot of work, including updating internal documents, best practices, internal training for how and when to use a certain feature, etc.
But to be fair also Rust is guilty of keeping the base small and leaving important stuff in external crates (serde, tokio,...).
I'm not sure that this is a good thing? With Julia you can also write doctests which work great, but having a separate test set as a Julia _project_ offers a lot of flexibility. For instance, we're now developing a Julia wrapper for Playwright to build end-to-end/UI tests which themselves have multiple dependencies. Having a test _project_ allows having as complex test cases as needed, with properly managed dependencies out of source. How would you handle that with an approach like Rust's?
A test project means that you can easily extend the testing capabilities of Base Julia - for Genie we use ExtendedTestSet which actually allows us to pick and run only some of the tests. Take a look at that.
I hope this helps.