Phoenix.new – Remote AI Runtime for Phoenix | Hacker News Reader

Phoenix.new – Remote AI Runtime for Phoenix

fly.io

639 pointswut42272 comments

I am a long time php dev who has been interested in learning elixir/phoenix for a while but never quite motivated enough.

I saw this and thought, if this doesn't get me to give it a go, nothing will.

Less than 45 minutes after signing up for fly.io, I have a multi-room tic tac toe game deployed.

https://tic-tac-toe-cyber.fly.dev/

I had it build the game, opting for a single room at first to see if that worked. Then I had it add multiple rooms on a different git branch in case that didn't work. It worked great.

I learned very little about elixir, phoenix, or deploying to fly.io up to this point, and I already have a nice looking app deployed and running.

I know a lot of devs will hate that this is possible, and it is up to me now to look at the steps it took to create this and really understand what is happening, which are broken down extremely simply for me...

I will do this because I want to learn. I bet a lot of people won't bother to do that. But those people never would have had apps in the first place and now they can. If they are creating fun experiences and not banking apps, I think that is still great.

You guys have been releasing amazing things for years only to be poorly replicated in other languages years later.. but you really outdid yourselves here.

I'm blown away.

edit: is there a way to see how much of my credits were used by building this?

Was the graphic design created from prompts too? It's surprisingly nice, especially considering you spent 45 minutes on it.

I told it that I wanted a two player tic tac toe game.

it give me a selection of "styles" and I chose neon retro.. I probably could have been more creative and typed in my own suggestion.

Other than that, I said absolutely nothing about how I wanted the layout.

It came up with the idea of listing all active games on the homepage, with the number of players in each, all on its own.

I went from "I want a two player tic tac toe game" to having one, and then added multiple rooms, and deployed it all in under 45 minutes, with little input other than that..

This is amazing on multiple fronts! I reset your usage, so the next round is on us! We shipped credits the day before launch, so usage UI is still TBD, but should be out next week. Thanks for the sharing your experience!

Hi Christ, is there any way to get more credits or BYO api key for anthoripic/openai? Im trying to make Kahoot clone and already spend more that 40 in a couple hours.

Based on how much they seem to charge (I blew through the $20 initial in like an hour, equivalent use in Claude Code would have been around $3), they're clearly making a pretty big margin on top of the API calls. I doubt they're going to allow BYOK

Did you figure out how much credit was used? I want to try this out, but $20 of credit can go quick doing agentic work

I'm not sure exactly but I think I used nearly all of it.

I've seen others say they went through the full $20 within 45minutes to an hour.

They are supposed to be adding a way to monitor usage soon.

Phoenix creator here. I'm happy to answer any questions about this! Also worth noting that phoenix.new is a global Elixir cluster that spans the planet. If you sign up in Australia, you get an IDE and agent placed in Sydney.

I know it's early days, but here's a must-have wish list for me:

- ability to run locally somehow. I have my own IDE, tools etc. Browser IDEs are definitely not something I use willingly.

- ability to get all code, and deploy it myself, anywhere

---

Edit: forgot to add. I like that every video in Elixir/Phoenix space is the spiritual successor to "15-minute rails blog" from 20 year ago. No marketing bullshit, just people actually using the stuff they build.

You can push and pull code to and from local desktop already: hamburger menu => copy git clone/copy git push.

You could also have it use GitHub and do PRs for a codex/devin style workflows. Running phoenix.new itself locally isn't something we're planning, but opening the runtime for SSH access is high on our list. Then you could do remote ssh access with local vscode or whatever.

> Running phoenix.new itself locally isn't something we're planning

So no plans to open the source code?

confirm

Everyone has to eat.

For sure. I'm just hesitant to recommend sending one's codebase to a server running code I can't inspect. I suppose that's the status quo with LLM's these days, though.

"15-minute rails blog" changed the game so I definitely resonate with this. My videos are pretty raw, so happy to hear it works for some folks.

run locally or in your private cloud would be amazing. The latter bit would be a great paid option for large enterprises

Amazing work.

Just a clarifying question since I'm confused by the branding use of "Phoenix.new" (since I associate "Phoenix" as a web framework for Elixir apps but this seems to be a lot more than that).

- Is "Phoenix.new" an IDE?

- Is "Phoenix.new" ... AI to help you create an app using the Phoenix web framework for Elixir?

- Does "Phoenix.new" require the app to be hosted/deployed on Fly.io? If that's the case, maybe a naming like "phoenix.flyio.new" would be better and extensible for any type of service Fly.io helps in deployment - Phoenix/Elixir being one)

- Is it all 3 above?

And how does this compare to Tidewave.ai (created as presumably you know, by Elixir creator)

Apologies if I'm possibility conflating topics here.

Yes all 3. It has been weird trying to position/brand this as we started out just going for full-stack Elixir/Phoenix and it became very clear this is already much bigger than a single stack. That said, we wanted to nail a single stack super well to start and the agent is tailored for vibe'd apps atm. I want to introduce a pair mode next for more leveled assistance without having to nag it.

You could absolutely treat phoenix.new as your full dev IDE environment, but I think about it less an IDE, and more a remote runtime where agents get work done that you pop into as needed. Or another way to think about it, the agent doesn't care or need the vscode IDE or xterm. They are purely conveniences for us meaty humans.

For me, something like this is the future of programming. Agents fiddling away and we pop in to see what's going on or work on things they aren't well suited for.

Tidewave is focused on improving your local dev experience while we sit on the infra/remote agent/codex/devin/jules side of the fence. Tidewave also has a MCP server which Phoenix.new could integrate with that runs inside your app itself.

> For me, something like this is the future of programming. Agents fiddling away and we pop in to see what's going on or work on things they aren't well suited for.

Honestly, this is depressing. Pop in from what? Our factory jobs?

Hopefully, from sitting by the pool drinking margaritas ... but I doubt we will get to keep our new found freedom.

Never going to happen. More efficiency and automation won’t lead to more free time and money for the masses, it will lead to fewer people employed, and those that are will be working the same hours for the same money but outputting more. Only the rich people will benefit.

In the long term. In the short term, we get to do the same work but faster.

Indeed, why would an employer pay us a high salary to sit by the pool? The benefits will go to the founders/investors and the customers. They'll benefit greatly from the increased output and lower costs, but the middlemen (SWEs) will be cut out. That's a great thing if you're a founder/investor or a customer, but not if you're the middleman. New opportunities may come around, but I don't think that's inevitable. It remains to be seen.

It will not be easier for founders/investor either. If couple prompts is all it takes to build your product, your potential customers will write those prompts themselves instead of buying your product.

Hot damn, that's a great point! Although I fully expect the models at some point to say stuff like, "I'm sorry I can't generate a <whatever> because that would violate Apple's/Google's/Whatever IP" and then have them enforce it with the power of government (copyright/patent/regulation/etc). There's also lots of industries where compliance requirements create a moat that might be difficult to get past, though that's probably just a short/medium-term problem.

True. But someone at the top will benefit. Either it’s the companies that can produce more of something that the end user can’t easily replicate themselves for whatever reason, or at least the LLM providers.

What I mean is, it will create value. Just not for the masses. And maybe not for the small businesses. If anything, it will let the big corporations do even more: a few big players doing everything and no little players at all.

Some people prefer to pay for others to handle things and take responsibility.

> Pop in from what? Our factory jobs?

Oh, you sweet summer child. ;)

You will pop in from the other 9 projects you are currently popping in on, of course! While running 10 agents at once!

And from which exactly am I earning an income to feed myself? Who's buying what I'm making? Where are they getting their money?

We're building a serfdom again.

LOL, what? Take on 10 projects at once, and start making way more money... if you're not an external-locus-of-control moron at least

You've literally been given an excavator when you currently have a shovel, and you're worried that other excavators will dig you out of a job. That is a literal analogy to your POV, here

How about our software engineering jobs, which will now entail managing a team of agents?

wow that sounds fun /s

Sounds preferable to managing people tbh

I understand that we are slowly taking away our own jobs but I do not find it depressing. I do find it concerning since most people do not talk about this openly. We are not sure how we are restructure so many jobs. If we cannot find jobs, what is the financial future for a large number of people across the world. This needs more thinking, honest acceptance of the situation. It will happen, we should take a positive approach to finding a new future.

Read up on the Jevons Paradox

> In economics, the Jevons paradox (/ˈdʒɛvənz/; sometimes Jevons effect) occurs when technological advancements make a resource more efficient to use (thereby reducing the amount needed for a single application); however, as the cost of using the resource drops, if the price is highly elastic, this results in overall demand increasing, causing total resource consumption to rise. Governments have typically expected efficiency gains to lower resource consumption, rather than anticipating possible increases due to the Jevons paradox.[1]

I do think there will be some Jevons effect going on with this, but I think it's important to recognize that software development as a resource is different than something like coal. For example, if the average iPhone-only teenager can now suddenly start cranking out apps, that may ultimately increase demand for apps and there may be more code than ever getting "written," but there won't necesarily be a need for your CS-grad software engineer anymore, so we could still be fucked. Why would you pay a high salary for a SWE when your business teams can just generate whatever app they need without having to know anything about how it actually works?

I think the arguments about "AI isn't good enough to replace senior engineers" will hold true for a few years, but not much beyond that. Jevon's Paradox will probably hold true for software as a resource, but not for SWEs as a resource. In the coal scenario, imagine that coal gets super cheap to procure because we invent robots that can do it from alpha to omega. Coal demand may go up, but the job for the coal miner is toast, and unless that coal miner has ownership stake, they will be out on their ass.

[1] https://en.wikipedia.org/wiki/Jevons_paradox

The coal miner would have to pivot to being someone who knows a lot about coal instead of someone that actually obtained it, they’d become more of a coal-advisor to the person making decisions about what type of or how much coal to get/what’s even possible with the coal they’re getting.

The future I’m seeing with AI is one where software (i.e. as a way to get hardware to do stuff) is basically a non-issue. The example I wanna work on soon is telling Siri I want my iPhone to work as a touchpad for my computer and have the necessary drivers for that to happen be built automatically because that’s a reasonable thing I could expect my hardware to do. That’s the sort of thing that seems pretty achievable by AI in a couple turns that would take a single dev a year or two. And the thing is, I can’t imagine a software dev that doesn’t have some set of skills that are still applicable in this future, either through general CS skills (knowing what’s within reasonable expectations of hardware, being able to effectively describe more specific behavior/choosing the right abstractions etc) or other more nebulous technical knowledge (e.g. what you want to do with hardware in the first place).

Another thing I will mention is that for things like the iPhone example from earlier, there are usually a lot of optimizations or decisions involved that are derived from the user’s experience as a human which the LLM can’t really use synthetically. As another example if I turned my phone into a second monitor the LLM might generate code that sends full resolution images to the phone when the phone’s screen is much lower, there’s no real point for it to optimize that away if it doesn’t know how eyes work and what screens are used for. So at some point it needs to involve a model of a human, at least for examples like these.

> The coal miner would have to pivot to being someone who knows a lot about coal instead of someone that actually obtained it, they’d become more of a coal-advisor to the person making decisions about what type of or how much coal to get/what’s even possible with the coal they’re getting.

I definitely agree that there will be some jobs/roles like that, and it won't be 100% destruction of SWEs (and many other gigs that will be affected), but I can't imagine that more than a small percentage of consultants will be needed. The top 10% of engineers I think will be just fine for the reasons you've said, but at the lower levels it will be a blood bath (and realistically maybe it should as there are plenty of SWEs that probably shouldn't be writing code that matters, but that feels like a separate discussion). Your point about other skills/knowledge is good too, though I suspect most white collar jobs are on the chopping block too, just maybe shortly behind.

Your future is one that I'm dreaming about too (although I have a hard time believing Apple would allow you to do that, but on Android or some future 3rd option it might be possible). Especially as a Linux user there have been plenty of times I've thought of cool stuff that I'd love to have personally that would take me months of work to build (time I've accepted I'll never have until my kids are all out of the house at least haha). I'm also dreaming of a day when I can just ask the AI to produce more seasons of Star Trek TOS, Have Gun - Will Travel, The Lieutenant, and many other great shows that I'm hungry for more, and have it crank them out. That future would be incredible!

But that feels like the smooth side of the sword, and avoiding a deep cut from the sharp side feels increasingly important. Hopefully it will solve itself but seeing the impacts so far I'm getting worried.

I appreciate the discussion and optimism! There is too much AI doomerism out there and the upsides (like you've mentioned) don't get talked about enough I think.

Computers are not special. They are just a heat engine like everything else. We feed them concentrated energy that they dissipate to do work. They do work on data: we give it data (some of it is called code) and it gives us back data. It's all about the information content, how does that data communicate something and relate to the world?

"Training" is just upfront work. Why on Earth people expect to get from the machine that processes data some novel information that did not exist before?

This whole fantasy hinges on not understand the sheer amount of data these LLMs are being trained on, and some magical thinking about it producing some novel information ex nihilo somehow. I will never understand how intelligent people fall into this patterns of thought.

We can only get from computers what we put into them.

> Why would you pay a high salary for a SWE when your business teams can just generate whatever app they need without having to know anything about how it actually works?

It depends on how good the AI is. The advantage of an SWE is that they have a systems thinking mindset, so they can solve some problems more efficiently. With some apps in won't matter, but with others will.

One potential positive outcome is that we will be able to solve more and bigger problems, since our capacity for solving problems has been augmented with AI.

Thanks for everything you do Chris! Keep crushing it.

Do you have a package for calling LLM services we can use? This service is neat, but I don't need another LLM IDE built in Elixir but I COULD really use a way to call LLMs from Elixir.

Req.post to /chat/completions, streaming the tokens through a parser and doing regular elixir messages. It's really not more complicated than that :)

even less complicated, just set stream: false in your json :)

the ai agent runs inside the same remote runtime as the app. does it share the BEAM vm or run as a port process?

The agent runs outside your IDE instance and controls/communicates with it over Phoenix channels

how are they isolating ai agent state from app-level processes without breaking BEAM's supervision guarantees?

They run on separate machines and your agent just controls the remote runtime when it needs to interact with the system/write/read/etc

appreciate the clarity, that helps.

quick followup if the agent's running on a separate machine and interacting remotely, how are failure modes handled across the boundary? like if the agent crashes mid-operation or sends a malformed command, does the remote runtime treat it as an external actor or is there a strategy linking both ends for fault recovery or rollback? just trying to understand where the fault tolerance guarantees begin and end across that split.

token auth and re-handshake. Agent is respawned if it's no longer alive, and project index is resynced

Any takeaways on using Fly APIs for provisioning isolated environments? I'm looking into doing something similar to Phoenix.new but for a low-code server-less workflow system.

1 week of work to go from local-only to fly provisioned IDE machines with all the proxying. fly-replay is the unsung hero in this case, that's how we can route the *.phx.run urls to your running dev servers, how we proxy `git push` to phoenix.new to your IDE's git server, and how we frame your app preview within the IDE in a way that works with Safari (cross origin websocket iframes are a no go). We're also doing a bunch of other neat tricks involving object storage, which we'll write about at some point. Feel free to reach out in slack/email if you want to chat more.

Thanks, I might hit you up when I'm in the weeds of that feature.

Would love to read about some of the techniques for how you accomplished this.

This looks amazing! I keep loving Phoenix more the more I use it.

I was curious what the pricing for this is? Is it normal fly pricing for an instance, and is there any AI cost or environment cost?

And can it do multiple projects on different domains?

It’s $20 per month if you click through, and I haven’t tried it but almost certainly the normal hosting costs will be added on top.

Thanks, apparently didn't click through enough

I've tried it, the $20 of included credits lasted me about 45 minutes

How tightly coupled to Fly.io are generated apps?

Everything starts as a stock phx.new app which use sqlite by default. Nothing is specific to fly. You should be able to copy the git clone url, paste, cd && mix deps.get && mix phx.server locally and the app will just work.

If you're willing to share, is maintaining that modularization the plan going forward? I'm pretty happy to use and pay for this and deploy it to fly, but only as long as I'm not "locked in."

Does it mean I can build and deploy a SQLite based app on fly.io with this approach without using Postgres? If yes, how does the pricing for the permanent storage ( add) needed for SQLite works? Thanks

You would need to add a fly volume ($0.15/GB per month of provisioned capacity ), also check out https://fly.io/blog/litestream-revamped/

1. What's your approach to accessibility? Do you test accessibility of the phoenix.new UI? Considering that many people effectively use Phoenix to write front-ends, have you conducted any evals on how accessible those frontends come out?

2. How do you handle 3rd party libraries? Can the agent access library docs somehow? Considering that Elixir is less popular than more mainstream languages, and hence has less training data available, this seems like an important problem to solve.

It seems like they're giving you lower level building building blocks here. It's up to the developer to address these things. Instruct the agent to build/test for accessibility, feed it docs via MCP or by other means.

They use the Daisy UI component library in 1.8+ Phoenix versions which should have basic accessibility baked in.

Hi just to confirm as I cannot find anything related to security or your use of using submitted code for training purposes. Where is your security policies with regards to that.

Ask some security questions, I'll get you security answers. We're not a model company; we don't "train" anything.

We don't do any model training, and only use existing open source or hosted models. Code gets sent to those providers in context windows. They all promise not to train on it, so far.

Did I not say it good enough, Kurt?

You said it terribly to be honest

The Phoenix.new environment includes a headless Chrome browser that our agent knows how to drive. Prompt it to add a front-end feature to your application, and it won’t just sketch the code out and make sure it compiles and lints. It’ll pull the app up itself and poke at the UI, simultaneously looking at the page content, JavaScript state, and server-side logs.

Is it possible to get that headless Chrome browser + agent working locally? With something like Cursor?

Playwright has an MCP server which I believe should be able to give you this.

When Roo Code uses Claude, it does this while developing. It renders in the sidebar and you can watch it navigate around. Incredibly slow, but that’s only a matter of time.

Does it work with VSCode GitHub Copilot LLM provider? They have Claude in there

What is the benefit of this vs. just running your agent of choice in any ole container?

The whole post is about that. Not everything is for everybody, so if it doesn't resonate for you, that's totally OK.

Oh geez so sorry for the dumb question! I read a lot about the benefits of containerization in general for agents, but thought it might be enlightening/instructive to know what this specific project adds to that (other than the special Elixir-tuned prompting).

But either way I hear you, thanks so much for taking the time to set me straight. It seems like either way you have done some visionary things here and you should be content with your good work! This stuff does not work for me for just circumstantial reasons (too poor), but still always very curious about the stuff coming out!

Again, so sorry. Congrats on the release and hope your day is good.

You're fine! Just encouraging people to read Chris's post. :)

Gotcha! I'll keep reading it I guess until I see what I am missing! Good job again!

I did none of the work! I'm just like Flavor Flav or Bez in this situation. I will relay your congrats to Chris and the team, though. ;)

Bad analogy. Bez was the best singer and most important member of that group.

Shaun Ryder sets a low bar. Definitely the best maracas player though.

Kurt's our Ryder.

Huh ok! Well you sure are quite passionate. Thanks either way I guess.

I'm assuming you're using FLAME?

How do you protect the host Elixir app from the agent shell, runtime, etc

Not using FLAME in this case. The agent runs entirely separately from your apps/IDE/compute. It communicates with and drives your runtime over phoenix channels

Oh interesting. So how do messages come from the container? Is there a host elixir app that is running the agent env? How does that work?

Yes, elixir app deployed across the planet as a single elixir cluster. We spawn the agents (GenServer's), globally register them, and then the end-user LiveView chat communicates with the agent with regular elixir messages, and the IDE is a phoenix channels client that communicates with and is driven by the agent.

Just tried it out, but it's unclear what the different buttons at the bottom of the chat history does. The rightmost one (cloud with an upwards arrow) seems to do the same as the first?

I'm also having trouble with getting it to read PDFs from URLs. I got this error:

web https://example.com/file.pdf Error: page.goto: net::ERR_ABORTED at https://example.com/file.pdf Call log: - navigating to "https://example.com/file.odf", waiting until "load" at main (/usr/local/lib/web2md/web2md.js:313:18) { name: 'Error' }

/workspace#

Is there something comparable that works similarly but completely offline with appropriate hardware? Not everywhere has internet or trusts remote execution and data storage.

PS: Why can't I get IEx to have working command-line history and editing? ;-P

What LLM(s) is the agent using? Are you fine-tuning the model? Is the agent/model development a proprietary effort?

Currently claude 4 sonnet as the main driver, with a combination of smaller models for certain scenarios

Is there a transparent way to see credit used/remaining/topped up, and do you have any tips for how you can prompt the agent that might offer more effective use of credits?

The LLM chat taps out but I can't find a remaining balance on the fly.io dashboard to gauge how I'm using it. I _can_ see a total value of purchased top ups, but I'm not clear how much credit was included in the subscription.

It's very addictive (because it is awesome!) but I've topped up a couple of times now on a small project. The amount of work I can get out the agent per top-up does seem to be diminishing quite quickly, presumably as the context size increases.

Include optional default email, auth, analytics, job management (you know… the one everyone uses ::cough:: Oban ::cough::), dev/staging/prod modes (with “deployment” or something akin to CD… I know it’s already in the cloud, but you know what I mean) and some kind of non-ephemeral disk storage, maybe even domain management… and this will slay. Base44 just got bought for $80M for supplying all those, but nothing is as cool as Elixir of course!

These other details that are not “just coding” are always the biggest actual impediments to “showing your work”. Thanks for making this!! Somehow I am only just discovering it (toddler kid robbing my “learning tech by osmosis” time… a phenomenon I believe you are also currently familiar with, lol)

Watched the Tetris demo of this and it was very impressive. I was particularly surprised how well it seems to work with the brand-new scopes, despite the obvious lack of much prior art. How did you get around this, how much work was the prompt, and are you comfortable sharing it?

This is very cool. I think the primary innovation here is twofold:

1. Remote agent - it's a containerized environment where the agent can run loose and do whatever - it doesn't need approval for user tasks because it's in an isolated environment (though it could still accidentally do destructive actions like edit git history). I think this alone is a separate service that needs to be productionized. When I run claude code in my terminal, automatically spin up the agent in an isolated environment (locally or remotely) and have it go wild. Easy to run things in parallel

2. Deep integration with fly. Everyone will be trying to embed AI deep into their product. Instead of having to talk to chatgpt and copy paste output, I should be able to directly interact with whatever product I'm using and interact with my data in the product using tools. In this case, it's deploying my web app

look into Kasm workspaces.. great way to spin up remote docker-based linux desktops, and works great as an AI dev environment that you can use wherever you happen to be. There is homedir persistence, and package persistence can be achieved via some extra configuration that allows for Brew homedir-based package persistence.

https://hub.docker.com/r/linuxserver/kasm

https://www.reddit.com/r/kasmweb/comments/1l7k2o8/workaround...

>> Remote agent - it's a containerized environment where the agent can run loose and do whatever

How is this innovation?

Many people have not experienced the async agent workflow yet and fairly the major providers didn’t have offerings for them until a month or two ago.

It’s in fact one of my predictors for if they are going to be enthusiastic about agents or not.

And you wouldn’t think containerization would be a big leap but this stuff is so new and moving so fast that combining them with existing tech can surprise people.

It's less innovative and more trendy. A lot of the fly integration can be achieved by simply asking claude code to look up the docs for the fly cli tool.

I have recently been working with Google Jules and it has a similar approach. It spins up VMs and goes through tasks given.

It does not handle any infrastructure, so no hosting. It allows me to set multiple small tasks, come back and check, confirm and move forward to see a new branch on GitHub. I open a PR, do my checks (locally if I need to) and merge.

I’m torn on “is this the future”.

I worked all day on a Phoenix app we’re developing for ag irrigation analysis. Of late, my “let’s see what $20/mo gets you” is Zed with its genetic offerings.

It actually writes very little Elixir code for me. Sometimes, I let it have a go, but mostly I end up rewriting that stuff. Elixir is fun, and using the programming model as intended is enlightening.

What I do direct it to write a lot is a huge amount of the HEEX stuff for me. With an eventual pass over and clean it up for me. I have not memorized all of the nuances of CSS and html. I do not want to. And writing it has got to be the worst syntactic experience in the history of programming. It’s like someone said people lisp was cool; rather than just gobs of nested parentheses, let’s double, nay triple, no quadruple down on that. We’ll bracket all our statements/elements with a PAIR of hard to type characters, and for funsies, we’ll make them out different words in there. And then when it came to years of how to express lists of things, it’s like someone said “gimme a little bit of ini, case insensitivity, etc”. And every year, we’ll publish new spec of new stuff that preserves the old while adding the new. I digress…

I view agentic coding as an indictment on how bad programming has gotten. I’m not saying there wouldn’t be value, but a huge amount of the appeal, is that web tech is like legalese filled with what are probably hidden bugs that are swallowed by browsers in a variety of u predictable ways. What a surprise that we’ve given up and decided the key tools do the probabilistic right thing. It’s not like we had a better chance of being any more correctly precise on our own anyway.

Ah man I'm really happy to see this and excited to try it out.

As an Elixir enthusiast I've been worried that Elixir would fall behind because the LLMs don't write it as well as they write bigger languages like Python/JS. So I'm really glad to see such active effort to rectify this problem.

We're in safe hands.

in principle llms should do better on immutable languages since there is no risk a term will get modified by a distant function call.

In my experience, it's the functional part, not immutability, where they fall short. Any LLM can write immutable C# because it's easy and there's incredible amounts of training data.

good news, "immutable" is pretty much the only way that elixir is "functional" except for lambdas being first class datatypes (which is almost every language now)

Same, I watched a video from Theo where he says Next.js and Python will be the best languages because LLMs know them well, but if the model can infer, it shouldn’t be a problem.

Folks on YouTube have used Claude Code and the new Tidewave.ai MCP (for Elixir and Rails) to vibe code a live polling app in Cursor without writing a line of code. The 2hr session is on YT.

This one?

https://www.youtube.com/live/V2b6QCPgFTk

That's the one.

since models can't reason, as you just pointed out, and need examples to do anything, and the LLM companies are abusing everyone's websites with crawlers, why aren't we generating plausible looking but non working code for the crawlers to gobble, in order to poison them?

I mean seriously, fuck everything about how the data is gathered for these things, and everything that your comment implies about them.

The models cannot infer.

The upside of my salty attitude is that hordes of vibe coders are actively doing what I just suggested -- unknowingly.

But the models can run tools, so wouldn't they just run the code, not get the expected output, and then exclude the bad code from their training data?

That seems like a feedback loop that’s unlikely to exist currently. I guess if intentionally plausible but bad data became a really serious problem, the loop could be created… maybe? Although it would be necessary to attribute a bit of code output back to the training data that lead to it.

For what its worth, AI already has subpar data. Atleast this is what I've heard.

I am not sure, but the cat is out of the box. I don't think we can do anything at this point.

Worried it might fall behind… further? I love LiveView, Phoenix, Elixir, OTP. But the ecosystem is a wasteland of abandoned packages.

If Phoenix.new helps solve that problem, I’m all for the effort. But otherwise, the sole focus of the community leaders of Elixir should be squarely and exactly focused on creating the incentives and dynamics to grow the base.

Compare, for example, Mastra in TypeScript or PydanticAI in Python. Elixir? Nothing.

Not here to bash. It’s more just a disappointment because otherwise I think nothing comes close.

All languages are a wasteland of abandoned packages, i.e. there is a very long tail of stuff no one has maintained for years. It’s all relative to the mindshare. For its size, Elixir is doing quite well.

Most languages require maintenance.

Some languages—Clojure is a good example—have packages from 10 years ago, entirely unmaintained, that still work great because no maintenance is needed.

This is also true for Elixir though. A lot of "unmaintained" Elixir packages still work fine.

That's their point (I think, lol).

In my experience, Elixir is very much on that end of the spectrum as well. I'm wondering if GGP just considers packages that don't have updates for 6 months as "unmaintained" or "dead" because they come from Javascript world where everything is, well... you know.

Broken and deprecated from inception?

Fragmented, 'not developed here, and 'only I can create the one standard everyone needs'?

It's not the long tail. It's that the HEAD of packages in Elixir are also often poorly maintained or not maintained. The fundamental question for any developer: can I be productive quickly? Despite all that Elixir has going for it, the answer is often "no."

Want a first-party client library for the service you're using? Typically the answer is "too bad, Elixir developer." And writing your own Finch or Req wrapper for their REST endpoint simply isn't a valid answer.

>For its size, Elixir is doing quite well.

I'm actually arguing the opposite. Elixir is not doing well because of its size. So how can that be influenced and changed?

What packages in Elixir have you found unmaintained/missing in the ecosystem? Genuinely curious.

Probably the highest profile and most consistent example would be Stripe. The most popular Stripe wrapper for Elixir’s docs point to a 2019 Stripe API version: https://github.com/beam-community/stripity-stripe

Worse still, the quality of Stripe’s own docs have really degraded this decade for anyone not using a language they have an SDK for. Most of their newer docs assume m have a drop-down toggle for on backend language with a few popular languages and no option for “other”. Example: https://docs.stripe.com/billing/quickstart

None of this is a fault of anyone working on Elixir or Phoenix but it definitely has an effect of discouraging some of the fledgling entrepreneur types who Elixir would otherwise be a near perfect fit for, as Rails was in the late aughts.

anything OAuth

There is an excellent (maintained, funded, audited AND with official certification) erlang/Elixir library for that: https://github.com/erlef/oidcc

I have just shipped a production service centered around OAuth and interfacing with OpenID Connect servers.

Old packages usually still run great in Elixir though.

This is such a weird thing to say and I see it all of the time. It sucks people have been tricked into thinking a library must be updated every 2 weeks in order to still be relevant.

You think just because an author bumps the version number of a library it's somehow better than a library that is considered complete?

It boggles my mind that people actually think this way.

You must never have been a Ruby developer. “I notice this library hasn’t been updated in 8 days, is it still being maintained?”

LLMs not writing it well might be the biggest current selling point of elixir lol.

Oh lol I love that angle!

Selling point from a developer and career perspective for sure. Its also fun to program in and at least for me made me think about solutions differently.

Its a negative point for engineering leaders that are the decision makers on tech stacks as it relates to staffing needs. LLMs not writing it well, developers that know it typically needing higher compensation, a DIY approach to libraries when there aren't any or they were abandoned and haven't kept pace with deprecations/changes, etc.

In the problem space of needing a web framework to build a SaaS, to an engineering leader there are a lot of other better choices on tech stack that work organizationally better (i.e. not comparing tech itself or benchmarks, comparing staffing, ecosystem, etc.) to solve web SaaS business problems.

I don't know where I stand personally since I'm not at the decision maker level, just thought I'd point out the non-programmer thought process I've heard.

This is such a weird meme, Claude crushes elixir especially a fullstack app in liveview

Yea CC is great with phoenix / liveview. It’s been doing things that teach me new tricks about elixir I didn’t know yet.

What's a good place to start for a completely naive but interested user?

Sorry, I only just saw this comment. Feel free to reach out (email in profile) and I’d be happy to chat.

Claude and o3 are both excellent (if a bit erratic) elixir developers.

Claude 3.5 produces very good Elixir/Phoenix code. Haven't tried 3.7 much but I assume it's only going to get better from here

I use o3, it's really good with Elixir. I prefer it to Claude, but Claude does a decent job as well.

If you want to take your website and business down, use ChatGPT-4o's code

This last few weeks I've been going hard on LLMs to put together a new prototype project. I've exclusively been using Claude Sonnet 3.7 within Zed (via github copilot) and it' fantastic.

From time to time it tries to do something a little old-school, but nothing significant really. It's very capable at spitting out entire new features, even in liveview.

Over all the experience has very productive, and at least on-par with my recent work on similar sized python and nextjs applications.

I think because I'm using mostly common and well understood packages it has a big leg up. I also made sure to initialise the phoenix project myself to start with so it didn't try to go off on some weird direction.

Assuming you are on the $20 Zed plan? Has the 500 prompts/mo been sufficient for you? I'm debating between the Zed and Claude $20 plans-- no doubt I'd get better value from Zed's?

I'm on the free plan and have been using it via GitHub copilot instead, as the current project is a work one and they pay for that.

Before this I did a small project and I hit the 50 free tier limit through Zed by the time I was about 90% done. It was a small file drop app where internal users could create upload links, share them with people who could use them to upload a file. The internal user could then download that file. So it was very basic, but it churned out a reasonable UI and all the S3 compatible integration, etc.

I had to intervene a bit and obviously was reviewing everything and tweaking where needed. But I was surprised at how far I got on the 50 free prompts.

It's hard to know what you really get for that prompt limit though as I probably had a much higher number of actual prompts than they were registering. It's obviously using some token calculation under the hood and it's not clear what that is. All in all I probably had about 60-70 actual prompts I ran through it.

My gut says 500/mo would feel limited if I was going full "vibe" and having the LLM do basically everything for me every day. That said, this is the first LLM product I'm considering personally paying for. The integration with Zed is what wins for me over Claude, where you'd have to pay for API credits or use Claude Code. The way they highlight code changes and stuff really is nice.

Bit of a brain dump, sorry about that!

Thanks, that gives me some new things to think about

I have used Zed's plane with Claude and also Claude Code. They are very different experiences. Zed's agent work is very much a set it, go away, review, give some tips to it, iterate. As long as you use the Sonnet and absolutely avoid the burn mode (formerly max mode), it should do a lot of work for you. The main limitation I hit is the context window. As the codebase gets larger, it takes more context for it to get going and then it tends to have a hard time finishing. I find that about 4 prompts works for a feature that would take me a few hours to code.

For Claude Code, the limit is reset every 5 hours so if you hit it, you rest a bit. Not that big a deal to me. But the way it works I find much more stressful. It is reviewing just about everything it is doing. It is step-by-step. Some of it you can just say Yes, do it without permission, but it likes to run shell commands and for obvious reasons arbitrary shell commands need your explicit Yes for each run. This is probably a great flow if you want a lot of control in what it is doing. And the ability to intercede and redirect it is great. But if you want more of a "I just want to get the result and minimize my time and effort" then Zed is probably better for that.

I am also experimenting with OpenAI's codex which is yet a different experience. There it runs on repos and pull requests. I have no idea what their rate/limit stuff will be. I have just started working with it.

Of the three, disregarding cost, I like Zed's experience the best. I also think they are the most transparent. Just make sure never to use the burn mode. That really burns through the credits very quickly for no real discernible reason. But I think it is also limited to either small codebases or prompts that limit what the agent is going through to get up to speed due to the context window being about 120k (it is not 200k as the view seems to suggest).

Helpful feedback, thank you!

Try claude --dangerously-skip-permissions

Thanks for the tip. That does work much more like Zed's integration. I used multipass to setup a VM, created a non-admin user, restricted its internet with tinyproxy, mounted the repo I am working on, and I don't worry about the danger. Just have to make sure to ensure the directory mounted is backed up. I do find that I hit the limits and have to wait for it to reset. That is either a good time to take a break or maybe supplement with Zed. Zed has the feature that one can pay for extra prompts. The context window with Claude Code seems less of an issue than in the Zed integration. It also has memory comapctification if necessary though I find most of my feature work finishes before hitting that limit.

Yeah – as someone who works in Common Lisp, I wish there was way to do complementary training for LLMs with existing corpora of codebases. Being able to read access documentation doesn't do much, unfortunately, to help with more general issues with correctness of output.

I found them to be pretty solid for writing Elixir (not perfect but neither is it with JS) the last couple of months.

Burnt through some credits pretty quickly. The first few minutes of using it felt like a glimpse of what it was supposed to be like, but otherwise it spent a lot of time not getting basic things right with the UI and before I knew it I was done. Roughly 90 minutes for $20 it's not a good value when you can ostensibly have the same experience on your computer and have control over every aspect. I still can't clone the latest revised version of the codebase it created to my local computer. Between that and Fly's non-existent documentation, no usage meter of some kind, and the lack of unpaid support (even though I am paying to use the service?) makes me want to avoid Fly, which is unfortunate because I think it does a lot of things right, especially the tunneling and dev experience outside of phoenix.new.

I've wasted a lot of time and energy on stuff that doesn't matter, so I can hardly judge anyone else on what they focus on, but man does it feel bad to have community leaders actively focus on building out tooling that is anti-worker. I think the only way I'd feel more conflicted is if Fly.io started building weapons systems for the military. I guess that wouldn't be shocking considering some of their lead's beliefs.

It's safe to say that if either Chris or I believed this to be anti worker, we wouldn't be working on it. He's spent the last 10+ years working on Phoenix specifically to improve the lives of the people doing the work.

My experience with software development is maybe different than yours. There's a massive amount of not-yet-built software that can improve peoples' lives, even in teeny tiny ways. Like 99.999% of what should exist, doesn't.

Building things faster with LLMs makes me more capable. It (so far) has not taken work away from the people I work with. It has made them more capable. We can all build better tools, and faster than we did 12 months ago.

Automation is disruptive to peoples' lives. I get that. It decreases the value of some hard earned skills. Developer automation, in my life at least, has also increased the value of other peoples' skills. I don't believe it's anti worker to build more tools for builders.

Exactly. And as more software is written, the demand and possible set of softwares increase.

It's really a matter of positive sum/growth mindset vs scarcity/status quo mindset.

Maybe, but it's zero sum to the people with money. We saw wage growth in the lowest end during the Biden admin and it drove the bosses insane.

> There's a massive amount of not-yet-built software that can improve peoples' lives, even in teeny tiny ways. Like 99.999% of what should exist, doesn't.

We agree on this completely, however you and I know there are plenty of people without jobs in the world who could be employed to do this work. You are spending your finite amount of time on earth working with services that are trying to squeeze the job market (they've said this openly) rather than spending it increasing the welfare of workers by giving them work.

> Automation is disruptive to peoples' lives.

You know the difference between automation and the goals of these companies. You know that they don't want to make looms that increase the productivity of workers, they want to replace the worker so they never have to pay wages again.

rather than spending it increasing the welfare of workers by giving them work.

Saying the quiet part loud here.

Do you believe making things easier and more accessible is bad for workers? I don't think it inherently is or isn't, it just depends on who benefits from the increased efficiency. I think that's more of a problem with your economic system, or wealth distribution.

Overall I think we would all be happier if efficient machines take away the drudgery of our daily work and allow us to focus on things that really matter to us. . . as long as our basic needs are met.

> Do you believe making things easier and more accessible is bad for workers?

Nope, I've been doing it for 16 years.

You can think of it as just automating the boring tedious stuff so us humans can focus on the harder problems like strategy, direction, design, GTM, etc.

The days are numbered where humans are sitting typing out code themselves.

It's akin to the numbered days of type writer secretaries of the 20th century.

I know what stories workers in the industry are using to cope with working with capitalists that have explicit goals of eliminating workers.

I'm sure your poor understanding of the history of improved tooling, like "type writer secretaries", will be a soft comfort in the future.

And you don't think capitalism is the reason we have these computer jobs to automate away in the first place?

No, because I’ve read a history book.

The same logic that would lead one to believe that AI is anti-worker should also lead one to believe that software as a whole is anti-worker.

Sure, if you don't think about it at all.

The argument you're responding to is effective enough, based solely on the fact that it has led me to second-guess whether I chose the right line of work, that it would be worth expounding on what you think is wrong with it.

I am inclined to agree with you. Card-carrying socialist and all that. But I wonder if you could share a good-faith rebuttal of this point.

It's more than evident that software has automated away all kinds of wage labor from the aforementioned typist pools to Hollywood special effects model-makers.

What's different now is that it is actually the software creators’ labor that is in danger of automation (I think this is easily overstated but it is obviously true to some degree).

I get that it feels different for us now that OUR ox is the one being gored. And I do think there will be no end of negative externalities from the turn towards AI. But none of that refutes the above respondent's point?

A few things:

1. Typists are still around and so are special effects model-makers. 2. People who program aren't in danger of automation. 3. These services are entirely unsustainable, they will absolutely not last at their current pace.

The premise of this entire work, detailed by the creator, is to utilize a program to reduce the amount of work a programmer is required to do. They believe ultimately, like most results of improved automation, that this will result in more things we can work on because we have more time. I agree that this would likely be the case! We could also simply make more programmers, could we not? Why haven't we? Do the 18k people homeless in my city tonight not deserve a shot at learning a skill before we even think about making the work easier per person?

Finally, and more to the point, genAI is built by and designed to eliminate workers entirely. The money that goes into those services funds billionaires who seek to completely and totally annihilate the concept of the proletariat. When I make a tool that helps workers at my job do their job better I am not looking to eliminate that person from the company.

Most tech isn't "Anti worker". What determines pro/anti worker are laws and government policies that reciprocate with the cultural norms we adopt. At the moment, money in U.S. politics is the most anti-worker phenomena I can think of. The ultra wealthy have a monopoly on the incentives that create policy and how our lives are ordered. The only power working people seem to have is the ability to impose consequences via rogue guerilla acts of protest and violence (Luigi Mangion) . Hopefully, AI is a Frankenstein monster the public learns to wield to facilitate more of these "consequences" and upend the monopoly the super wealthy have on policy incentives and change the way politics is funded for good. It's a new world and a Hawaiian or New Zealand doomsday bunker isn't going make a difference.

This is very neat, and right up my alley as both someone really into Elixir and who thinks agentic AI is the future.

I have a question about how you manage context, and what model you use. Gemini seems the best at working with give context windows right now, but even that has its limitations. Thinking about working with Claude Code, a fair bit of my strategizing is in breaking down work and managing project state to keep context size manageable.

I'm watching the linked video and it's amazing seeing it in action, but I'm imagining continuing to work on a project and wondering if it will start losing its way so to speak. Can you have it summarize stuff, and can you start a session clean with those summaries, and have it "forget" files it won't need to use for this next feature, etc?

"Sign in with fly.io" takes me to a page asking me to pay $20 but the plan details are vague - what exactly is included in "$20/mo of Built-In AI Assistance Builds, refactors, and debugs right in your IDE"?

This is a situation where we've been pushing on Chris to get this out into the world quickly, and there's a lot of packaging stuff like this that isn't fully put together yet. Thanks for calling it out! We'll get to it over the next week.

Phoenix.new looks powerful, and I'll definitely play with it.

I've been daydreaming of an agentic framework that maximally exploits BEAM. This isn't that, but maybe jido[0] is what I'm looking for.

0. https://github.com/agentjido/jido

TIL; That is a very interesting library

This thread on Elixir Forum is a good read if you are considering building agents with Elixir. Jido's author weighs in also.

https://elixirforum.com/t/is-anyone-working-on-ai-agents-in-...

I'm a little surprised by the sentiment here that LLMs don't do well with Elixir. I've had a pretty good experience using AI tools on Phoenix/Elixir side projects.

LLMs are definitely a lot better at Elixir than they used to be - the gap has closed somewhat. I still perceive a gap though, especially when trying to do more complicated things in Phoenix and LiveView (as opposed to just raw Elixir.)

Which LLMs do you use that you find are best with Elixir/Phoenix?

I haven't really used much other than Claude.

I guess I should also note that I haven't really used LiveView much.

I've only used LLMs with Elixir, so I don't have any other experience for comparison, but I've found that although Claude frequently employs the wrong approaches in Elixir, I usually know when he'll have trouble and just ask him to read pertinent documentation first. So long as he's read the manual he seems to do just fine.

Hmm, just signed up to check it out but no trial just "$20/mo of Built-In AI Assistance" without any mention of usage limits?

Same. Agents can be very expensive. Plus I have no idea how reliable or effective this actually is in practice. Would love to try it first.

it's wild to me all this progress with AI, but at the same time, on my brand new mac, going through the readme to try out phoenix, it can't even get past the first step without an error (says it can't find postgres), yet the docs say I don't need postgres and it will default to sqllite if postgres and mysql can't be found.

hard to put confidence in AI vibe hacks when the basic stuff just doesn't work.

* (Mix) The database for Myapp.Repo couldn't be created: killed

I am probably doing something wrong but I hate agents for coding. I like the autocomplete and the prompt to generate snippets but when it starts modifying code in many files so fast all at once, tries a bunch of stuff and never know when to stop it pisses me off more than anything else. Because most the time if it had stopped and let me do the 10% last part it would have been actual legit code.

Mindblowing! This is 100x VB6. The generated UIs are beautiful and professional. I am still trying it out and building an app for tracking expenses but it is working very well. The conversational dialogue it has with the developer is just fantastic. I am amazed at how clear the user experience was in Chris' mind. I am not sure what LLM is being used but this is better experience than any LLM. Given this is first version, I look forward to what comes next!

Few issues:

1. The 150 message limit is understable but it suddenly pops up and you lose significant work. I was working on UI mockup and just as I had finished and was ready to go on implementation, this limit appeared and significant part of my work was lost. 2. After the first credit, the credit seems to exhaust pretty fast which makes it expensive, especially when you are trying it out. 3. Also I don't understand when you ask it to prototype different screens, why does it overwrites the same file. 4. It is not able to stop to seek user feedback but keeps trying different approach which kind of exhausts the credit. It would be nice if it describes its approach, so the human developer can provide their feedback. 5. It seems it is using OpenAI because it is often self-congratulatory to the point of being annoying sometimes.

I love the idea of Phoenix and server side rendering (I happen to work on SkyMass, a related project).

This is a tangential comment and should not detract from what Chris and team have created. I think closing the loop between agent and the running output is a great/critical step forward.

However, I find using AI to build transitional Apps with a UI is a bit like improving the way automobile steering wheels are made. In a world that soon won't need steering wheels at all.

If the AI is so good to write the code for an App, how much longer before you won't need those Apps in the first place? And then the question is, what will fill the role that Apps play today.

I don't think we want to move to a world where everything we use is AI driven all the time.

A coded app is significantly more efficient to execute, and more predictable, than dealing with AI in most situations.

I don't disagree that code is far more efficient than inference. But what are those apps? A lot of apps are fetching some data, massaging it, rendering UI to let the user view / update data. Could the AI do some of that "work" for you, so that you don't need those dashboards / buttons / forms in the first place? Maybe you have an agent that does a db query (instead of a human viewing a dashboard) and takes some action (instead of the human clicking a button).

I think it boils down to: if the AI screws up what I asked it to do, who do I have to hold accountable? If the answer is that there is no one I can hold accountable, because the AI agent I used removes any and all onus of responsibility in its terms of service, then I'm not going to use it for anything non-trivial.

This looks really cool, but I gotta say I'm a bit uneasy with the apparent(?) closed-source + hosted + branding. "mix phx.new" is the way to generate a new Phoenix project, but "Phoenix.new" is closed source Fly.io product for building Phoenix projects?

Feels like we're getting into a weird situation if LLM providers are publishing open source agentic coding tools and OSS web app frameworks are publishing closed source/non-BYOK agentic coding tool. I realize this may not be an official "Phoenix" project but it seems analogous to DHH releasing a closed-source/hosted "Rails.new" service.

This is very cool! I will say though, my spidey senses kick in when looking at stuff like this, and make me wonder about how much I'm going to get vendored in here. Could I use it develop a site off fly.io? If the answer is no, then I'd say this is cool and I think useful for people who need something quick and simple and out of the box, but not something I would ever use on a serious production project.

It’s just producing Elixir/Phoenix code that is stored in GitHub and can be deployed anywhere.

The answer is yes. What would you say then?

There’s a “clone Git repo” thing in the left side bar, use that to clone the project locally, mix deps.get, mix phx.serve and you’re up. You can deploy this anywhere you want.

If the DB, Auth libraries and such are not tied to fly.io, then yep that's cool. Happy

The mental models of Elixir/OTP and AI Agents are very compatible. I’ve felt for a long time that it would be one of the best platforms for building AI agents.

Would you elaborate why?

So is Phoenix.new a Fly.io product, or just under the fly umbrella? Also, is pricing clearly laid out anywhere (including what the additional costs are for permanently deployed/hosted services that arise from Phoenix) ? Didn't dig too hard admittedly, but wasn't obvious where to find or look for pricing information on the front page on mobile

Any chance of open sourcing the model instructions for this? Do you feed it all the Phoenix/LiveView/Elixir docs, or have you written more specialised instructions?

I find Claude to have quite a bit of problems trying to navigate changesets + forms + streams in my codebase, just wondered if you had any tips of making it understand better :)

A bit sad that the language and framework so enjoyable to write an read will be mostly hidden in a coding box.

And thinking about it made me realize that soon there will be a completely different programming language used solely by coding agents. ChatGPT gives an interesting take on this, "The fundamental shift is that such a language wouldn’t be written or read, but reasoned about and generated. It would be more like an interlingua between symbolic goals and executable semantics, verbose, unambiguous, self-modifying, auto-verifiable, evolving alongside the agents that use it").

This makes me very uneasy. Not in what it is per se, but in what it shows about the direction of Phoenix.

I've been working with Phoenix a lot the last few months, and I like it a lot. But I do get the sense that the project suffers from wanting to perpetually chase the next new thing, even when that comes at the expense of the functional elegance and conceptual cohesiveness that I think is Phoenix' main strength.

LiveView is a great example. It's a very neat bit of tech, but it's shoe-horned surprisingly awkwardly into Phoenix. There's now a live view and non-live view way to do almost everything in Phoenix, and each has their own different foibles and edge cases. A lot of code needs to work with both (e.g. auth needs to happen at both levels, basically), meaning a surprising amount of code needs to have two, nearly identical variants: one with traditional Plug idioms, and then another using LiveView equivalents. Quick little view helpers end up with either convoluted 'what mode am I in?' branching, or (more likely) in view-mode-dependent wrappers around view-mode-independent abstractions. This touches even the simplest helpers (what is the current path?) and becomes more cumbersome from there. (And given the lack of static analysis for views, it can be non-trivial to even find out what is and isn't actually working where.)

Not every website should be a live view (e.g. hiking directions, for example), but that is clearly the direction of travel in Phoenix. Non-live views get the disparaging moniker 'dead views', and the old Phoenix.HTML helpers have been depreciated in favour of <.form />-style live components. The generators depend on those, plus Tailwind, Hero Icons and (soon) DaisyUI, all fetched live from various places on the Internet on build. This tight coupling to trendy dependencies will age poorly, and it makes for bumpy on-boarding (opinionated and tightly coupled isn't necessarily a smoother experience, just a more inflexible one).

So with all of that in mind, while I'm not shocked to see Phoenix jump on the vibe coding hype train, I guess I am disappointed.

The revelation that AI is now writing PRs for Phoenix itself is not confidence inspiring. I rely on frameworks like Phoenix because I don't want to have to think about the core abstractions around getting a website to my users; I want to focus on my business logic. But implicit in that choice is the assumption that someone is thinking about those things. If it's AI pushing out Phoenix updates now, my trust level and willingness to rely on this code drops dramatically. I also do not expect Phoenix' fraying conceptual cohesiveness to get any better if that's the way we're headed.

Phoenix is still an amazing piece of tech, but I wish I felt more at ease about its future trajectory.

I love everything I read about Phoenix. It's definitely the framework I'm going to use the next time I need to scratch an itch.

Having a full stack that is easy to use as a learning sandbox is incredibly helpful in that regard, so this looks amazing.

This is incredible. It does seem quite expensive compared to Zed or Claude Code now it's on Pro. But neat enough I've burned through the $20 subscription credit despite being a bit of an AI sceptic. This seems to have a much better handle on UI design (unless I'm missing something with the other agents), but as a solo dev I'm becoming quite convinced. It's also got me to try out fly again.

I couldn't get Tidewave working but I must try again to see if Tidewave with Claude Code would offer this level of awesome.

ps. @fly - please let me buy more credit, I just get an error!

Thanks for the feedback! Send your fly email to chris@fly.io and I'll get things sorted out. We'll throw you some credits for the trouble :)

Hero.

Hey @chrismccord, very confused but this is a collab between you and the FLY.IO project right? Like I can't eject the app from this and run it myself? This isn't an open source Phoenix project?

You can just use git to clone the code

Chris is a hacker’s hacker.

A hacker's hacker who charges for closed source AI tools which work in hosted environments only. Yea, right.

Come on, devs need to eat. Companies need cash to employ people. After all that he has done for open source, you're complaining that something isn't free? You know you can export the code at any time right?

I'm not saying he's a bad dev, just hardly fits the hacker ethos.

We want things we can tinker and toy with from the inside.

Technically this is really. Practically I don’t understand the point. Who is the target demographic? People that don’t have a local dev environment?

It's not really about the remote IDE. It's about an integrated environment where the agent can do everything it needs (install OS packages, inspect the code, view the app via a browser etc) in order to build what you want. It could end up being the place you 'start' an app, before exporting it and fleshing out the features locally.

So the primary benefit over any other AI agent IDEs is it has access to a browser?

Ya I really am not the target demographic for this since I don't use AI agents in my IDE anyway.

It does seem to perfectly fit fly.io in the sense that I also don't care about "edge" apps.

Beautiful demo! How do I build agents like this?

Does anyone know any great resources to learn how to design agents? Tool agnostic resources would be awesome.

Thanks! Everything is overly complicated in this space. It's probably far easier than you think. The open secret is it's just a loop that POST [provider]/chat/completions.

Elixir is particularly well suited here. In Elixir this is a genserver doing http posts and reacting to the token stream. The LiveView chat gets messages from the genserver agent regardless of where it is on the planet, and the agent also communicates with the phoenix channel websocket talking to the IDE machines with regular messages, again anywhere they are on the planet.

I talk about this quite a bit in my ElixirConfEU talk and distill things down: https://youtu.be/ojL_VHc4gLk?si=MzQmz-vofWxWDrmo&t=1040

Wow, thank you for the link, it clarified how tool calling and "choice-making" works.

It's like helping LLMs use a computer; like building an interface for it.

Ok, this is enough to get me started.

This is great. I had to back out of a phoenix project and rewrite it in Django because I couldn't get good AI assistance. I'm pretty inexperienced with Elixir and Phoenix but understand the benefits enough to want to make projects in it. So this is really cool.

I had this experience too. Though most of my issues were with my model not necessarily with Elixir itself so much as understanding the Phoenix model, state, and CLI. Maybe even differences in versions? Wasn't always clear.

I find that baffling. Why not just write the Elixir yourself?

Not just baffling, but concerning. LLM's are great for learning new languages, but terrible for outputting code you don't understand yet hope to maintain.

Yet, more and more people are going to be doing exactly this.

This is really cool! And, that you did it in a few weeks is insane.

How did you get VS Code embedded in your app? I'm aware of projects like Monaco, and that vscode.dev exists - so it's clearly possible - but I didn't realize it was something others could build upon?

Again, kudos!

What LLM does Phoenix.new use?

claude 4 sonnet as the main driver atm, and a mix of smaller models depending on the scenario

I'm building an agent right now (or rather, extending an agent I build a few weeks ago in a couple hours) and I would love to hear more about which scenarios get assigned to which models.

(I almost just asked you on company Slack but figured the answer would be more broadly interesting.)

Based on the blog post, Phoenix.new uses Claude 3 Opus as its underlying model, which explains its strong performance with Elixir/Phoenix codebases.

What model is it using for all the agentic work?

What usage limits do we get with the $20 monthly price?

Thank you!

I really wish I could move to those nice new editors, but as a vim user I just feel paralyzed when I cannot use vim bindings. And all "emulations" I tried are just incomplete.

I'm with you. I'm going to try Zed in the next couple days based on the response to my comment here. https://news.ycombinator.com/item?id=44322560 . I'm stuck with vim. My fingers nearly only work vim, but I managed to move to neovim, which worked. Maybe (something else) can work too.

You can pull the repo, tweak it locally with Vim, push it back and ask the LLM to work on top of that. No need to use the built in IDE if you don’t like it.

as an avid vim user who moved to emacs evil-mode for a better vim than vim, and now who uses vscode with vscode-vim, it pains me to admit a web browser based editor is a better vim than vim. Somehow starts faster and is less kludgey and more scriptable. You can install extensions on phoenix.new, so vim is not a blocker for you. I drive vim emulation in it every day both on desktop app and within phoenix.new. Couldn't use it without it :)

My main issue with vim emulation is that you cannot do file management and windows management.

In my vim workflow I keep splitting/unsplitting windows and I like to have a file browser I can navigate with vim bindings.

Phoenix needs an ActiveRecord-like database abstraction layer. Many Rails developers try Phoenix at some point because they may need better performance. They’re so accustomed to the Rails structure that they assume Rails has done everything right. However, Ecto and ActiveRecord are two very different beasts. When Rails developers try out Ecto, they often feel there’s too much boilerplate and believe the Rails design is much more intuitive. This, I think, is one reason Phoenix struggles to attract Rails developers. If it can’t please Rails users, it will rarely appeal to others.

The Ash framework is a data abstraction layer you light want to check out, although I'm not familiar with Rails/ActiveRecord to tell if it's closer to what they're after.

My primary concern with Phoenix is how bad it performs in LLMs and I basically went back to Node/React/Rails for LLMs.

This is very exciting and I’ll check it out!

What you mean by performs bad in LLMs?

LLMs don’t know Elixir/Phoenix very well

Claude Code is pretty proficient in it. Others, not so much. True.

Did you consider creating a LLM.txt and some variants for Phoenix?

Some libraries have text-based documentation for LLMs which works great in my experience.

Why wouldn't LLMs work as well with Elixir as python or JS? LLMs don't parse an AST.

Because of the amount of Python and JS in the wild is much more than the amount of Elixir code, so the LLMs have much more data to base their answers on.

Thanks

Very cool. Does it use Phoenix 7 or 8 in the video?

1.7 or 1.8, not 7 or 8

Thanks for correcting my typo.

1.8rc, which is going 1.8.0 momentarily

Integrating AI assistance directly into an Elixir IDE could boost productivity, especially for newcomers. Excited to see how remote SSH and local workflows develop!

For us SaaS Founders, GrowthHackers, Product folks, us non-devs.. What are some solid use-cases for it today?

Is the site down?

this is the excuse i needed to revisit phoenix-elixir after a decade

ty fly team

Well of course I have to test it.

Disabled on news.ycombinator.com

Heyy! Now we know why fly.io was shilling for AI a couple weeks ago.

"They are not making money off AI".was the most common response to my pointing out they were shilling AI. Feels good to be right.

Maybe you mean the "My AI Skeptic Friends Are All Nuts" blog post on fly.io?

Where they have this nugget about plagiarism:

> But if you’re a software developer playing this card? Cut me a little slack as I ask you to shove this concern up your ass. No profession has demonstrated more contempt for intellectual property.

So I guess if you have concerns about them using any code you upload using this tool you can shove it up your ass.

I'm surprised they are investing into this. I checked Phoenix recently because I was interested in LiveView and there isn't even an official AWS SDK for Elixir.

Honestly doubt the AI stuff is going to move the needle much if you can't even have a dependable S3 client.

But there's two actively non-official maintained libs.

What are you talking about, there has been a AWS client forever and I've never had a problem. It's not something you really need an official sdk for they are anyway often just reference because you might want different performance characteristics.

https://hex.pm/packages/ex_aws https://hex.pm/packages/ex_aws_s3

I've usually not seen more than 3 or so official SDK for most services and there are a lot more programming languages than that. For example Microsoft's Graph API doesn't have an official Ruby client, they have one that sort of works.

Neither of them are official which is often a non starter for some large enterprise customers.

Not only large enterprise customers. Anyone who's thinking mid or long term.

Why do you need an official SDK to make http calls?

Why do you even need a framework like Phoenix? Just write everything yourself! /s

I still don't understand this. If you are big enough then you get Amazon to make an official sdk, if you aren't then what exactly are you looking for?

The official aws cli used to talk to the soap interface and used regex instead of actually doing correct error handling and that was used by so many tools. Even though it used to break horrible.

It's quite a niche you are talking about, not big enough to debug open source code but still big enough to require SLA for SDK and not being able to talk Amazon into creating it. It's generated code, it's not rocket science.

What I have experienced is that software licence, where you are sending data to, where you are hosting it and having access to audit the code has usually been a bigger concern.

But then again big organisations often have really specific concerns. So I'm not doubting your statement it's just that I have never heard it before.

> what exactly are you looking for?

I'm not looking for anything. I'm describing my experience when evaluating Elixir/Phoenix recently.

I'm also questioning the investment into AI tooling when there are far more pressing issues that are hurting adoption.

If you want we can schedule a quick video call. Just curious about the problems you are facing.

The main lib everyone uses, :ex_aws, has been actively maintained for literally over a decade[1]. Official or not, it's used by literally the entire community, since even non-AWS services often will support its API.

1. https://github.com/ex-aws/ex_aws/releases?page=2

Considering the horror the official AWS CLI is this seems like a strange example. I’ve used both the non official libraries and they work fine. The one that is auto generated doesn’t feel very Elixir, but that’s to be expected.

> I’ve used both the non official libraries and they work fine

Maybe fine today but what about 5 years from now?

Can you say, with any degree of confidence, if these these libraries are going to be properly maintained in the future? No, you cannot.

Goes for every library out there though. Official or not.

Not really. You can be much more confident the official AWS SDK will be available 5 or even 10 years from now.

Meanwhile I am a happy user of :ex_aws or :req_s3 which has done everything I need it to do. Object ops, iam policies, etc. A dependable S3 client has been there for years. The elixir core team doesn't need to maintain it. ReqS3 is one of my favorite things to use: https://hexdocs.pm/req_s3/readme.html

Maybe you can guarantee Phoenix will be maintained 5-10 years from now but that's really not the case for some random library on Github.

If you look around you'll see this kind of stuff is really one of the biggest blockers for Elxir and Phoenix. Especially for something as fundamental as cloud storage.

Not sure what you're talking about..

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