It's brilliant: all useMemo and useCallback can be removed and you get the same runtime performance and then some, at the cost of only a slight increase in code size.
A small downside at the moment is the build time. This change will hopefully help address that because it will no longer depend on babel.
We have used React Compiler in production for a large ecom / media website for about a year. Performance has been fine overall, and we haven't ran into any major bugs attributable to it in that time.
Speaks volumes to the strengths of the language, also speaks volumes that LLMs lift the barrier of entry for Rust programming, the borrow checker woes can be offloaded to the model, you focus on all the other programming logic.
Whats funny is I had been using Rust more with Claude because of this, and before Anthropic did their rewrite of Bun I tried a Rust rewrite of a C# project I had laying around (.NET 3.5 from back in 2008) it wasnt perfect but its nearly there now, mostly for fun, and I did it because for a little while I realized LLMs can be useful for more serious refactors, and figured it might be good for a language rewrite. Sure enough.
I think rewriting tooling that takes text and transforms it in a language like Rust is fine for JS projects, so is Go, which is why TypeScript is migrating to Go. The “free” optimized speed increases are worth it, at the temporary cost of dealing with the migration for a year or two, which with LLMs trims down the initial work into a week effort it seems? Wild.
I'm sure its technically possible, you might need to provide a bit more context if you expect anyone to change course here and port it to a programming language approximately no one has heard of rather than Rust though. What makes you think that would be a good idea?
Just cause it isn't used for webshit doesn't mean "approximately no one" has heard of it.
Lean is pretty much the most popular language mathematicians use today for computer-assisted proofs. More mature audiences may know about Rocq, Isabelle, etc., but Lean was already popular enough for a few people I know to have written their PhD theses on it about a decade ago.
I think GP is joking about a port to Lean because that would at least produce a formally verifiable output.
Oh, PhDs, you're right, that's not approximately no one... It's probably approximately one.
I like Lean (and more generally dependent types) but ffs Lean has a very, very small userbase for a project like this. GGP would have to really justifyv the benefits for such a switch.
Never heard of it, and I nerd out on programming languages. Reminds me of a convo yesterday with my coworkers where I noted I never heard of Sheerpower a language someone who worked there had done, and I have heard of languages so old and niche most people are shocked.
My first programming interview my interviewer was like what the heck are you doing with D? And he noted he has a room full of devs where nobody knows what D is.
I think they use something called “flow” last time I’ve checked, it’s like typescript but when I went to visit the website with more information it was so slow it crashed my browser.
Are you sure? The React compiler is a fairly new addition to React, Flow is Facebook's old alternative to Typescript, but Typescript won the ecosystem in terms of broad adoption in the end. I think Flow is barely used today, I would be really surprised if they choose it for a new tool, even for a Facebook project.
You may be thinking about React itself, not the new compiler? I'm sure there must be some flow in there still from back in the day.
You may be right. I think Flow was a predecessor to TypeScript.
I just checked out Flow and woah. First-class syntax sugar for React. Maybe cool. (If it doesn't break catastrophically in a sane build system like Vite)
The benefit of Rust over TypeScript is that Rust is faster.
TypeScript is memory-safe, but you can't really control where the memory comes from. In Rust you have structs, traits, references and all sorts of things to control both your memory usage and your memory efficiency, and you just don't really get that in TypeScript. Plus, in Rust it's a lot easier to utilize multithreading -- JS is notoriously tedious to parallelize (message-passing between workers is a bit annoying compared to structured concurrency in Rust)
Why are they porting the Babel-isms? They should be using Oxc tooling directly, not hanging onto JavaScript parsers, IMHO -- isn't the benefit of porting to Rust that you can use fast native code?
It seems backwards that they are freezing the Babel AST into the interoperability contract and only using the more efficient native representations in an isolated fashion -- shouldn't it be the other way around?
OXC is not the only consumer, so using the OXC AST wouldn't particularly make sense? I thought it was pretty well explained in the PR:
> Note that the conversion from any AST into our HIR is complex, and we can only maintain one version. Hence we've aligned on using a Babel-like AST as our public API. Another key point is that we don't yet implement our own scope analysis (since the TS version of the compiler relied on Babel's scope analysis), so for now we require that the scope data be serialized. It's a denormalized graph, and some metadata has to be stored to associate nodes with scopes. We're open to feedback about the AST and scope representation - we iterated a bit just to get things to work, but it can be more optimal.
I saw, I just don't understand the rationale for picking Babel over OXC or something else as the interchange format -- other than "we were already doing it this way". After all, you know what they say about temporary solutions.
What I mean is, if you're going to rewrite it in Rust, why rewrite Babel rather than leaning on the existing ecosystem? I know they're not actually rewriting Babel, just reusing the semantic layout of its AST, but it's feeling a bit like the MediaWiki parser situation to me (roughly "if we started from scratch today, we wouldn't choose to have it this way, but we started a different way before, and it's been a difficult path to get to where we want to be"). Maybe that's a fairly remote analogy but it feels similar.
Are people actually using the react compiler?
Haven't heard about since ages ago when it was extremely slow
Yes absolutely.
It's brilliant: all useMemo and useCallback can be removed and you get the same runtime performance and then some, at the cost of only a slight increase in code size.
A small downside at the moment is the build time. This change will hopefully help address that because it will no longer depend on babel.
Very insightful, thanks. I just delved into it, starting here: https://react.dev/learn/react-compiler/introduction
We have used React Compiler in production for a large ecom / media website for about a year. Performance has been fine overall, and we haven't ran into any major bugs attributable to it in that time.
<something> rewrite to rust using AI sound like meme now.
Speaks volumes to the strengths of the language, also speaks volumes that LLMs lift the barrier of entry for Rust programming, the borrow checker woes can be offloaded to the model, you focus on all the other programming logic.
Whats funny is I had been using Rust more with Claude because of this, and before Anthropic did their rewrite of Bun I tried a Rust rewrite of a C# project I had laying around (.NET 3.5 from back in 2008) it wasnt perfect but its nearly there now, mostly for fun, and I did it because for a little while I realized LLMs can be useful for more serious refactors, and figured it might be good for a language rewrite. Sure enough.
I think rewriting tooling that takes text and transforms it in a language like Rust is fine for JS projects, so is Go, which is why TypeScript is migrating to Go. The “free” optimized speed increases are worth it, at the temporary cost of dealing with the migration for a year or two, which with LLMs trims down the initial work into a week effort it seems? Wild.
> you focus on all the other programming logic
Does that actually happen?
I think it's fine to experiment, just communicate with your users and make sure its opt-in.
Seems like they kind of did that? The thread seems like people already were waiting on this, so that's positive.
Curious but can we use lean4 as port target instead of Rust?
I don’t think lean4 compiled code is as efficient as rust. For verification purposes, there are some tools allowing formal verification of rust code.
I'm sure its technically possible, you might need to provide a bit more context if you expect anyone to change course here and port it to a programming language approximately no one has heard of rather than Rust though. What makes you think that would be a good idea?
> approximately no one has heard of
Just cause it isn't used for webshit doesn't mean "approximately no one" has heard of it.
Lean is pretty much the most popular language mathematicians use today for computer-assisted proofs. More mature audiences may know about Rocq, Isabelle, etc., but Lean was already popular enough for a few people I know to have written their PhD theses on it about a decade ago.
I think GP is joking about a port to Lean because that would at least produce a formally verifiable output.
Oh, PhDs, you're right, that's not approximately no one... It's probably approximately one.
I like Lean (and more generally dependent types) but ffs Lean has a very, very small userbase for a project like this. GGP would have to really justifyv the benefits for such a switch.
Never heard of it, and I nerd out on programming languages. Reminds me of a convo yesterday with my coworkers where I noted I never heard of Sheerpower a language someone who worked there had done, and I have heard of languages so old and niche most people are shocked.
My first programming interview my interviewer was like what the heck are you doing with D? And he noted he has a room full of devs where nobody knows what D is.
What is the react compiler written in currently?
Uh, TypeScript?
I think they use something called “flow” last time I’ve checked, it’s like typescript but when I went to visit the website with more information it was so slow it crashed my browser.
Are you sure? The React compiler is a fairly new addition to React, Flow is Facebook's old alternative to Typescript, but Typescript won the ecosystem in terms of broad adoption in the end. I think Flow is barely used today, I would be really surprised if they choose it for a new tool, even for a Facebook project.
You may be thinking about React itself, not the new compiler? I'm sure there must be some flow in there still from back in the day.
You may be right. I think Flow was a predecessor to TypeScript.
I just checked out Flow and woah. First-class syntax sugar for React. Maybe cool. (If it doesn't break catastrophically in a sane build system like Vite)
Isnt the benefit of rust that it's memory safe? Is typescript not?
I think the benefit of rust here is that it's not hosted whereas typescript is
The benefit of Rust over TypeScript is that Rust is faster.
TypeScript is memory-safe, but you can't really control where the memory comes from. In Rust you have structs, traits, references and all sorts of things to control both your memory usage and your memory efficiency, and you just don't really get that in TypeScript. Plus, in Rust it's a lot easier to utilize multithreading -- JS is notoriously tedious to parallelize (message-passing between workers is a bit annoying compared to structured concurrency in Rust)
Quite sure performance and not memory safety is the issue here.
Why are they porting the Babel-isms? They should be using Oxc tooling directly, not hanging onto JavaScript parsers, IMHO -- isn't the benefit of porting to Rust that you can use fast native code?
It seems backwards that they are freezing the Babel AST into the interoperability contract and only using the more efficient native representations in an isolated fashion -- shouldn't it be the other way around?
OXC is not the only consumer, so using the OXC AST wouldn't particularly make sense? I thought it was pretty well explained in the PR:
> Note that the conversion from any AST into our HIR is complex, and we can only maintain one version. Hence we've aligned on using a Babel-like AST as our public API. Another key point is that we don't yet implement our own scope analysis (since the TS version of the compiler relied on Babel's scope analysis), so for now we require that the scope data be serialized. It's a denormalized graph, and some metadata has to be stored to associate nodes with scopes. We're open to feedback about the AST and scope representation - we iterated a bit just to get things to work, but it can be more optimal.
I saw, I just don't understand the rationale for picking Babel over OXC or something else as the interchange format -- other than "we were already doing it this way". After all, you know what they say about temporary solutions.
So isn't not changing more sensible than changing to an arbitrary alternative?
The current developers surely are more familiar with the Babel representation than OXC, so why switch?
What I mean is, if you're going to rewrite it in Rust, why rewrite Babel rather than leaning on the existing ecosystem? I know they're not actually rewriting Babel, just reusing the semantic layout of its AST, but it's feeling a bit like the MediaWiki parser situation to me (roughly "if we started from scratch today, we wouldn't choose to have it this way, but we started a different way before, and it's been a difficult path to get to where we want to be"). Maybe that's a fairly remote analogy but it feels similar.
now we need to port angular compiler to rust!
We should compile Firefox to wasm, and run Firefox inside Firefox so we can Rust while we Rust