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From Rust to Ruby(xlii.space)
87 points by xlii 8 hours ago | 53 comments
JSR_FDED 3 hours ago | parent | next [-]

This defies belief. “I wanted to scratch a technical itch. My local AI completed the job in 30 minutes. I never pressed Start to see if it works, but I did write a blog post about it…”

iririririr 20 minutes ago | parent | next [-]

* it wrote a blog post

otabdeveloper4 an hour ago | parent | prev [-]

> This defies belief.

Akshually it's pretty normal for 2026.

sevenzero 12 minutes ago | parent [-]

Yup, since the rise of AI, I still didn't find any product built by it that's even remotely useful to me... People build prototypes a lot, but these are usually buggy and not worth putting money into.

daemin 4 hours ago | parent | prev | next [-]

At first I thought this would be an interesting article, but as soon as they mentioned using an LLM to do the conversion I lost all interest. It's like saying "I wanted this done so I got my underling to do it, here is my story...". Like why would I bother to read it then, as it was clearly not you doing the conversion or putting any thought into it.

pjmlp an hour ago | parent | next [-]

The biggest problem is that this is software development going forward.

Programming languages don't really matter outside craft programming.

As LLM improve, it will eventually be a market to specify in which kind of language the specification should be generated.

The UML and RUP crowd has had their vengeance.

daemin 43 minutes ago | parent [-]

It doesn't have to be, we have the power to change it by just not using LLMs to generate code-like text sequences.

But if anyone is having their revenge it is the "idea guys", not the UML jockeys.

eager_learner 3 hours ago | parent | prev [-]

you sound jealous :)

shevy-java an hour ago | parent [-]

That's an assumption. How do you infer that from written text? I can not infer that.

To me it is super-strange that one uses AI to come to the conclusion that language x is better than language y. In the past people spent some time using both languages for a while, before reaching any conclusion. With AI it seems insta-gratification or insta-evaluation now. I am beginning to see why Google ruined its search engine for real humans - those who control AI rule the world now. People aren't even noticing this how dependent they are becoming on AI in general.

digitaltrees 3 hours ago | parent | prev | next [-]

I built a set of gems (propel_rails) that takes the already terse Ruby on Rails code to the next extreme. It generates a set of top level classes like an API controller and some concerns that then create a full restful resource (model, controller, serializer, unit and e2e tests) with 0 boilerplate code. The controller ends up being only a list of all permitted attributes the api will accept because the restful actions are automatically generated. It’s a bit hard to fully describe but the meta programming power of Ruby really does make amazing things easy.

nine_k 3 hours ago | parent [-]

This sounds like CRUD, distilled.

I suppose it works in terms of your domain model?

october8140 4 hours ago | parent | prev | next [-]

I'm not sure any language + framework prioritizes developer happiness as much as Ruby on Rails.

pjmlp an hour ago | parent | next [-]

I have been pretty happy with Java and .NET frameworks, regardless of the lack of appeal in SV influenced circles.

Happiness doesn't always translate into performance, e.g. famous Twitter logo until they moved into JVM and Scala.

While Ruby on Rails took the fame, we already had similar experiences with AOLServer and Vignette, using Tcl.

We had our own variant at a Portuguese startup, and eventually the founders created OutSystems, one of the first graphical RAD tools for Websites and distributed systems development in low code/no code, targeting JVM or CLR infrastructure.

Now having said all of this, it is great to finally see CRuby getting a JIT in the box.

jdkoeck 2 hours ago | parent | prev | next [-]

It’s short term happiness at best, and at the expense of every other possible architectural characteristic (maintainability, performance, reliability, scalability, you name it).

Gigachad an hour ago | parent [-]

Updating Rails is one of the most painful processes ever. There is no real way to be sure it works. You just have to have 50,000 unit tests, cypress tests, and then hope and pray.

On any sufficiently large and old app, something will always break in a way that isn't caught by your tests or manual testing, and only shows up after it goes out live.

flats an hour ago | parent [-]

Honest question: what’s an example of a fully-featured web framework that makes upgrading a “large & old” application painless? In my experience, upgrading an underlying framework that a piece of complex software depends upon without breaking everything pretty much always requires time & good test coverage.

Gigachad 26 minutes ago | parent | next [-]

Type safety would fix 99% of the issues I've had upgrading Rails.

pjmlp 43 minutes ago | parent | prev [-]

Most Java and .NET ones, not everything breaks, statically compiled, so not as many unit tests required as in dynamic languages.

While it is deprecated, you can do a File=>New Project for Web Forms in 2026.

milch 3 hours ago | parent | prev | next [-]

I don't think I've ever been unhappier than working on a Rails project. See a bug on the site - something is rendering incorrectly. grep to find the view. Great, there's a method that is being called to render the buggy section. Grep for the method name - 0 hits. Amazing, it's something that is synthesized somewhere and I have no idea where. Guess I'll stop what I'm doing and read docs for an hour. If you do nothing but use Rails all day, sure, but the whole convention over configuration thing is such a huge anti pattern to me.

2 hours ago | parent | next [-]
[deleted]
jimbokun 2 hours ago | parent | prev | next [-]

I’ve had similar experiences with Spring Boot Java applications. Methods in stack traces that don’t exist in source code but are magicked into existence by annotations.

cyberpunk an hour ago | parent [-]

Hell with lombok it’s not even uncommon to have entire classes with no defined functions at all. shudder

craigmcnamara 2 hours ago | parent | prev [-]

method(:name).source is your friend

thunderbong 7 minutes ago | parent | prev | next [-]

Ruby? Yes.

Rails? Depends on the project.

tobyhinloopen an hour ago | parent | prev | next [-]

Rails is the worst. It’s so easy to make a mess and it’s hard to debug.

ch4s3 4 hours ago | parent | prev | next [-]

I get a similar feeling from Elixir and Phoenix without the method_missing foot gun.

jimbokun 2 hours ago | parent | prev [-]

I’m sure the LLM that translated the code was ecstatic!

c0balt an hour ago | parent | prev | next [-]

I'm sometimes amazed by project sizes, a 30k line codebase is small? I'm aware that the ceiling is high but 30k lines of code can encode so much information and behavioural nuance.

Maybe this is just my backend/network focus with Golang though. Scaling beyond 10-15k lines of code always was quite intimidating as it is usually where I lose the ability to just keep a model of the codebase fully in my head.

nine_k 3 hours ago | parent | prev | next [-]

If you can switch from Rust to Ruby, and it would make sense, choosing Rust in the beginning was a mistake.

preommr an hour ago | parent | prev | next [-]

> So in the end it seems I have (licks finger and turns to the wind) 1.47x better outcomes if the app were a Ruby on Rails app instead.

Am I reading this right... did this number just come out of thin air?

Is this just generated based on the vibes of the AI?

Also, to just add them up and compare them like that is just compounding nonsense on nonsense.

Ocha an hour ago | parent [-]

Tell me you haven’t actually taken engineering class by not telling me you haven’t taken an engineering class

Ocha an hour ago | parent [-]

Hint: weighted sum

faangguyindia an hour ago | parent | prev | next [-]

People think Ruby is slower than Rust, they'll be surprised to know Ruby is actually now faster than python but slower than Go or Rust.

Gigachad an hour ago | parent | next [-]

Speed has usually mattered less to me than memory usage. Most Ruby applications are speed limited by the database rather than Ruby. But when you have a bunch of background workers, every one chewing 2+ gb of memory stacks up.

I wrote one production Rust service and more impressive than the speed was that the thing ran on 30MB memory.

faangguyindia 11 minutes ago | parent [-]

I use Go for the same reason, but it seems php can use even less memory.

latexr 31 minutes ago | parent | prev [-]

Why would someone who thinks Ruby is slower than Rust (which apparently includes you) be surprised it’s faster than Python? Why does one thing have to do with the other?

rtpg 2 hours ago | parent | prev | next [-]

I do wonder if it'll ever be possible to get Rust tests to feel as nice to write as, say, test suites in Python or Ruby. I might just be missing a lot of helpers, but a part of me really wants to use a test metalanguage that (for example) RC's everything, gives me implicit casts from strings to what ever type I need, and a bunch of other stuff.

I've always found Rust object buildup to be pretty annoying.

aabhay an hour ago | parent [-]

dbg! Is your friend

encodedrose 3 hours ago | parent | prev | next [-]

>But before I did so I researched first. I asked a few instances to analyse the project in terms of gains of complexity, stability, testability, etc., and while (obviously) stability would drop (no types in Ruby) it’s not that awful (Sorbet has types in Ruby!).

Is it not a rage-bait argument to say that not having types implies less stability?

lmm 3 hours ago | parent [-]

No? Maybe the industry can now talk maturely about tradeoffs like that rather than pretending they don't exist.

JSR_FDED 3 hours ago | parent | prev | next [-]

To count lines of rust code:

fd . -e rs -uu | xargs cat | wc -l

Why not just:

find . -name '*.rs' | xargs wc -l

cauterize an hour ago | parent [-]

Or tokei

h4kunamata 3 hours ago | parent | prev | next [-]

From whatever to Go ... hype!

From Go to Rust ... hype!

From Rust to Ruby ... the new hype!?

shotgun 35 minutes ago | parent | prev | next [-]

Next try Elixir.

lmm 4 hours ago | parent | prev | next [-]

"I have no idea if it works or not because I haven’t yet tried running it. But it's 5x shorter!"

october8140 4 hours ago | parent | next [-]

The fact that it doesn't end with what happens when they run `rails server` makes me think they did it and didn't like the results.

pahbloo 3 hours ago | parent | prev [-]

Not a xkcd, but quite relevant:

https://web.archive.org/web/20091015091833/http://www.hackle...

shevy-java an hour ago | parent | prev | next [-]

> So I had to take a look around to remind myself what Ruby and Ruby on Rails are doing nowadays. They’re doing quite well.

Ah really?

Well ... let's look at TIOBE. Now I am aware that TIOBE sucks, it makes little sense, but even with that in mind, the claim that ruby is doing that well is simply factually WRONG, at the least right now:

https://www.tiobe.com/tiobe-index/

Ruby is ranked 23.

Rust is ranked 15.

Again, TIOBE has tons of issues, people pointed that out, but I am pointing here more at a trend. If you look at the graph:

https://www.tiobe.com/tiobe-index/ruby/

It is more obvious.

Now, I think ruby is a great language, I use it daily as the primary glue language to do literally everything. I call it the ultimate wrapper over C, which ruby ultimately is. But the claim "ruby is doing great" is just simply INCORRECT. And we haven't even gotten to RubyCentral mass-purging developers or adding random new corporate-driven rules to rubygems.org and what not. I never understood why I would be under 100k download restrictions when on github I have full control over my own (!!!) code. I call that an illegal hijacking attempt by RubyCentral (this was about a year before they mass-purged developers anyway, so I could nod my head wisely when that happened lateron, even though I had no advance knowledge, but it did not surprise me once the shopify corporate overlord pulled rank; and DHH sitting on the sidelines making joyful comments at the chaotic situation here on his blog. At that time I noticed that DHH indeed became a problem too).

> There are some typing initiatives (Sorbet), and the language itself is terse as ever.

No sane rubyist uses that typing crap, sorry. And matz isn't the biggest fan of slapping down mandatory types onto everything either. People whose brain is addicted to types, want them; I understand that problem. There is no way you can reason with them because they really WANT types. It's like someone starving for food; that person wants food. There is no way around that. Same with types for these people. And they want to change a language to that too. This is the annoying part. Many years ago I was surprised to hear haskell folks not wanting everyone. After that type addiction, I realise the haskell point of view: some people want to ruin languages. (You may debate whether types ruin ruby or not, but the main point here is that some people want to change a language into something that fits their brain more easily. Now I understand the haskell point of view, despite still thinking this is a snobbish elitist view of exclusion. But language integrity is also indeed important, so I understand that point of view these days.)

> while (obviously) stability would drop (no types in Ruby)

Absolute rubbish nonsense. Absolute. Totally incorrect claim made, from A to Z. But again, you can not reason with these type addiction people. Can't they go to PHP or some other language?

Let's reword it more neutrally then. Which claims and proof support the claim that stability drops because of "no types in Ruby"? Because I never ever had that happen in any code I wrote in ruby in the last +20 years. Yes, you need to be able to query what is possible; often you may have to do .is_a? or .respond_to?. Yes, this is not the same as "advance" type checks. I am not saying types are useless either. What I am saying is that the claim of "you lose stability without types" is ABSOLUTELY RUBBISH NONSENSE. But the brain of type-addicted folks is already set towards "types everywhere". This is the problem. They are trapped in their world of assumptions.

> So in the end it seems I have (licks finger and turns to the wind) 1.47x better outcomes if the app were a Ruby on Rails app instead.

Now he is pulling numbers out of ...

> I have a local LLM running on my (bought it for gaming pre-AI craze) 4090 Ti1 - I’m a free man with unlimited tokens2. So I thought: BRING IT ON!

Ah - and AI already deadlocked his brain on top of that. So not even writing any ruby code but just using AI. And using Rails either. Well, you can write web-applications without rails too. And that works extremely well. That also was the first thing I did when I switched from PHP to ruby back then. And I still don't need or use rails either.

> Since it is a relatively small project the conversion took ~30 minutes. I have no idea if it works or not because I haven’t yet tried running it. But there is one thing I checked, and stared at in horror

So he used AI and still has absolutely no idea about anything. These people don't see a problem with that. Oldschool people didn't go that way.

> That’s right folks! 77% decrease in line count; 4.49 lines of Rust code for each line of Ruby.

Well, using python would also have led to a significant decrease, so that is not surprising. C and C++ and Java also require a lot more information. Types in particular require more syntax and words in general, so really - nothing surprising here. That ruby is succinct and still elegant (except for this type crap) is one reason why people often stick to ruby.

> but I must say it’s looking clean and idiomatic for my dated eye.

But he is using AI here. How does he know that it is clean and idiomatic? The ruby code I write is (to me) very simple and straightforward, typical OOP but simple and practical at all times (whenever possible). AI does not generate such code. And a ton of ruby code on the world wide web, written by humans, looks as if someone beat you silly with a club on the head, before you started to write anything. Even well-used projects such as rack - anyone looked at the source code? Or of sinatra? It looks as if someone was drunk when writing the code. I am biased myself though; for instance, I find Jeremy Evans typically writes elegant ruby code. zverok writes fascinating projects, but his writing style is totally alien to me - your mileage may vary. The point is that there is not really a unified "idiomatic" ruby code. Look at this for instance:

https://github.com/ruby/ruby/blob/trunk/test/ruby/test_threa...

The code was as follows (the link no longer worked, I bookmarked it some years ago and now I can not find the new code but I assure everyone that this was that way, because I stored it locally):

    t1&.kill&.join
The safe navigation syntax has use cases, I am not denying that either. You can shorten some code significantly. But I find this syntax utterly horrible and decided that my code base will be protected against safe navigation horror.

Of course this is a subjective opinion. But ruby syntax is not automatically great merely because it is ruby. You need to think what you want and even more importantly what you don't want. And why.

> I can add types using Agents, so probably type safety can be alleviated

Yikes. And the worst part is: type-addicted people can not modify their brain. I've never seen a type-loving person abandon this love for types.

> Ruby/Rails is pretty much batteries+kitchen sink included, which beats 3GiB of compiled deps.

Ok. Not disputing that. But that more says a lot about Rust than Ruby really. Because the main question should be why you need so much code in Rust for that.

> Testing will be SO MUCH EASIER

Not disputing that either.

This is probably one of the strangest blog statements I have ever read. I think ruby is a great programming language, but this AI-powered transition is just ... strange. Basically he is not really using ruby. But praises ruby. While having AI generate the code. Am I the only one to find this extremely awkward?

tail_exchange 2 hours ago | parent | prev | next [-]

[dead]

honeybadger223 3 hours ago | parent | prev [-]

Idk why people are shitting on you. So many LLM haters on here. It’s changed the game completely and some people just don’t want to accept it.

I think this is cool. Verbosity of languages is important when it comes to coding with AI. I’ve found Go to be a happy medium.

xigoi 6 minutes ago | parent | next [-]

They wrote a blog post about code that they have not even tried running. Whether it’s LLM-generated does not matter.

loktarogar 2 hours ago | parent | prev [-]

If you replaced "AI" with "a developer" in this article, it might make more sense why it's being dunked on. It would be an article about someone telling someone to do something, and then when the work was done they were happy with the result. It's just a bit of a nothing all round

cwyers 40 minutes ago | parent [-]

> and then when the work was done they were happy with the result

It's worse than that -- they don't even know the result! They never tried to run it!