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koito17 18 hours ago [-]
I noticed borkdude posted this thread *and* he is listed as a contributor for this release.
For the longest time, I recall the opposition to async/await support being twofold:
1. adding support would require deep changes across the CLJS compiler (theller, creator of shadow-cljs, once tried and concluded this)
2. macros from libraries like Promesa provided similar convenience
There were some other arguments brought up at the time (e.g. just use core.async, expression-oriented languages aren't a good fit with async/await, etc.), but they were usually specific to one person rather than something you'd see repeated in forums.
In the Clojurians Slack, borkdude once stated he wasn't convinced it'd be impractical to add support. It seems that he eventually took the time and made it happen. Extremely thankful for that.
lilactown 17 hours ago [-]
I believe Borkdude showed it was possible by first implementing async/await in Squint, his alternative* implementation of ClojureScript, and then took those learnings to the core CLJS compiler.
midnight_eclair 1 days ago [-]
fun fact: clojurescript had support for asynchronous paradigm through core.async library (CSP style) long before async/await landed in javascript itself.
edit: i'm in no way trying to diminish the value of this release, just pointing out how cool it is that you can get new language features before they are available in the host language by just adding a library to your dependencies. clojure is awesome!
TacticalCoder 23 hours ago [-]
> fun fact: clojurescript had support for asynchronous paradigm through core.async library (CSP style) long before async/await landed in javascript itself.
Definitely. I was heavily using it and it worked: a few quirks but we did have async/await since more than a decade. I think I discovered it after watching a talk by David Nolen.
Since then I moved to minimal JavaScript on the front-end: SSE is one-way and that is beautiful. I'm glad to see many devs, from a great many different languages, now getting interested in SSE.
Here's a great, recent, talk by David Nolen called "A ClojureScript Survival Kit":
I cannot thanks David "Swannodette" Nolen enough for all the work he did on ClojureScript (and core.async) since its inception. And what's amazing in this talk is that he's actually excited at the idea that we may do away with ClojureScript and use pure Clojure (on the server-side) and server-side events, with just a tiny of JavaScript.
The real demo starts around 26:30. He shows a Webapp running on the client and how much resources it's using, then he shows the exact same Webapp running on the server and pushed one-way to the client using SSE. It is wild: resources usage drops to near zero.
YMMV but I find it easier to reason about my webapps and manage state now that I'm using a minimal DOM morphing lib: I used to have two REPLs (one for Clojure, one for ClojureScript) and lots of back-and-forth traffic and hard-to-track / reproduce state. Now everything is definitely snappier and way easier to reproduce.
I'm not saying SSE is going to work in every case though: YMMV. But in any case the video or at the very least the demo starting @ 26:30 is very much worth watching.
KingMob 1 days ago [-]
True, but there are many reasons to avoid core.async, especially in 2026.
It balloons up the Js artifact, has no inherent error model, and transforms into state machine code that's hard to read/debug if something goes wrong. Plus, the `go` macro encourages overly-large functions, because it can't transform code outside its own sexpr.
As one Cognitect put it, "core.async is beautiful nonsense".
jwr 1 days ago [-]
> has no inherent error model
I'll pitch in here, as I've been doing a lot of thinking about this issue and ended up writing my own (tiny) tools for handling anomalies, modeled on the very well thought-out https://github.com/cognitect-labs/anomalies categorization.
This is actually a much wider problem and not specific to core.async. Handling anomalies is difficult. It used to be that you would have exceptions and errors which would be thrown, unwinding the stack. This pattern no longer works in asynchronous code, or code that needs to pass anomalies between the server and the client. In practical applications, an anomaly might need to be returned from a function, passed through a `core.async` channel, then thrown, unwinding the stack on the server side, then caught and passed to the client side over a WebSocket, and then displayed to the user there.
Solving this well is not easy. I think my toolkit, iterated and improved over the years, is close to what I need. But I'm pretty sure it wouldn't handle all the real-world use cases yet.
But again, this is not specific to core.async in any way.
At a first glance, it does much more than what I would want to.
My status toolkit just extends the Cognitect anomalies to be statuses, adding ::failed (parameters correct, but could not perform request), ::ok, ::accepted and ::in-progress. It also adds a bunch of utility functions like status/?! (throws the parameter if it's anomaly, returns the parameter otherwise) and macros like status/-?> (threads if an expression is not an anomaly). That's it.
I deliberately avoid trying to do too much here.
stingraycharles 1 days ago [-]
For me it also lacks observability. It has been a few years since I last used Clojure, but I found manifold to be a much better fit for actual production code that you want to optimize.
I loved ztellman’s “everything must flow” talk on the topic.
KingMob 1 days ago [-]
Heh, I used to maintain manifold/aleph for a few years after Zach left the Clojure community.
ares623 1 days ago [-]
And here I thought I was too dumb to grok core.async all those years ago (ps I still am)
osener 24 hours ago [-]
Surprised to see Clojure/ClojureScript come up on socials more often all of a sudden. I used it professionally for a few years around ~2012 and like many others moved off JVM and moved into typed [functional] languages.
Is the sudden buzz due to agentic coding? Does it rip through code faster with no type checking and fewer invalid syntax errors and reserved keywords to deal with? are we in for a sexp resurgence?
slifin 23 hours ago [-]
Personally I moved from typed functional languages to Clojurescript and then Clojure around 10 years ago
Most serious Clojure code bases I'm aware of invest heavily in their test suite so yes you can just add a skill to your AI that tells it the most effective way to use your test suite then send it to the races
Some of my colleagues let the agent interact with the REPL and they report faster performance because the agent is not paying the start up cost on every interaction, personally I've been lazy there its fast enough for me
As you've hinted at Clojure does have less bits that get in the way, everything is true except false and nil, the language does not have order precedence table the core language supports immutable and persistent data structures as default
Everything is an expression nothing is a mixture of operators and expressions
map, reduce, filter are built in and expected in normal code
Code you wrote 10 years ago in Clojure will likely still work today the ecosystem and language authors treat breaking code as taboo
Of all the languages I've used its the least headache inducing and the most freeing in terms of expressing my ideas
Also the defacto reverse debugger Flowstorm is a programming dream
Its a lovely language if you want to be content
The flip side of that is most users take it for granted and don't talk about it much
There are also a lot of commercial Clojure programmers who do not understand the language and as a result not that happy, they often didn't willing choose it, probably not ready for it, I think most Clojurians should have gone through a decade of noticing things in their other languages they didn't like before using it
Rich Hickey the creator of Clojure does famously influential videos on software but that doesn't mean your colleagues have watched them or care
perarneng 23 hours ago [-]
Been coding in lots of languages with agentic coding and it performs much better with typed languages since it basically corrects the agent if it does any hallucination errors. Especially during major refactorings. I have been dealing with large untyped python code bases and it sucks with AI since if it's not covered with tests it's such a teadious job to make sure it did not break anything. The stronger the type system the better it is. Also AI model is trained on code and the more popular the language is the better the AI will be at it. ClojureScript while nice is not a major language so I would assume AI would perform worse in it compared to javascript.
But in the end. Choose typed languages or dynamic languages with type hints if you are going for the AI route.
giancarlostoro 23 hours ago [-]
Maybe that should be part of LLM benchmarking. If an LLM can handle untyped languages in the context window flawlessly, it would be a worthwhile accomplishment. I think For JS WebStorm loads a TS file for browser fundamentals and it helps drastically with this problem as well, sadly theres no similar concept for Python. Would be neat if someone implemented “Python Header Files” or something so you can provide type hints for these sort of projects.
Zak 24 hours ago [-]
Another feature that plays well with agentic coding is REPL driven development. I don't know why that approach hasn't caught on in more languages that could theoretically support it.
jhhh 7 hours ago [-]
I haven't kept up with cljs in a long time but I remember it originally being pitched as just clojure on js--at least I think that's how Rich originally described it. My impression was it was just supposed to be, as much as possible, another runtime. This change seems to add in features that are exclusive to cljs and actually conflict with clojure itself as await is already a keyword in clojure.core. Have the two impls diverged over time, or was this feature specifically important enough to the users to overcome the differences?
arikrahman 18 hours ago [-]
This is huge. I haven't been this excited about the Clojure ecosystem since Jank got announce (which is pretty recently to be fair)
timwis 1 days ago [-]
I wish an alternative to JS for the front end would catch on and be something more than obscure... I'd love to use something like clojurescript, but I struggle to imagine doing so for anything but a personal side project :/ Maybe this is easier to adopt if you're already a clojure shop for the backend?
I came to the conclusion that the best frontend is no frontend.
drob518 23 hours ago [-]
This is the way. Sure, the line is gray, but the more you can do on the server, the better off you are, IMO.
Smalltalker-80 24 hours ago [-]
Perhaps SmallJS, a Smalltalk built on top of JS,
that can run in browsers and in Node.js
(and also has async-await :-) :
https://small-js.org
jwr 1 days ago [-]
Don't be afraid, it's great! I certainly wouldn't call it "obscure", I've been using it for 10 years now to compile a complex app into highly-optimized client-side code. And the community is very welcoming and mature.
oDot 1 days ago [-]
You should try Gleam. I'm using it in production to great delight:
Massive, cheers dude and congrats on the release. I’d say it’s such a good time to get into Clojure/Script but, well … it has been for a while!
tombert 16 hours ago [-]
I'm not sure how I feel about this; wasn't part of the point of core.async to push all this stuff into channels? I'm not convinced that having a JS-style async keyword is an upgrade.
Borkdude 15 hours ago [-]
This is about using a JS feature without bringing in any additional dependencies like core.async. You don't have to use it and you can still use core.async. This was the most asked for feature in the recent ClojureScript survey.
tombert 15 hours ago [-]
Fair, I guess I import core.async into every project implicitly so I forgot that it's a separate dep.
slifin 1 days ago [-]
This is important for JavaScript interop without having to include additional libraries very cool and was missing for a long time
Congratulations on the release :-)
nbardy 1 days ago [-]
Seems like wrapping async await functions with CSP was a better way to handle this . Clojure already had a nicer pattern for this
embedding-shape 1 days ago [-]
You're still able to do so, as we've been able to in ClojureScript land for many years already, since ultimately they're just Promises! I don't think that's going away with this new function hints.
this release is about exposing the host language primitives to clojurescript
core.async isn't going anywhere, if async/await works better than promise based implementation, core.async will get an update in it's .cljs parts
chr15m 23 hours ago [-]
Epic win for cljs, congratulations!
seanclayton 24 hours ago [-]
I remember a decade ago when JavaScript got Async/Await. 10 years is quite a long time.
ertucetin 24 hours ago [-]
The beauty of Clojure/Lisp is that we have a nice macro system. Over the years, people created their own macros to simulate async/await. This is a powerful feature of Lisp, you don’t have to wait for an official release, you can just add that feature to the language yourself. Now we don’t have to use that custom macro anymore, which basically did the same thing.
worthless-trash 24 hours ago [-]
Clojurescript already had it, just didnt use native async.
moomin 19 hours ago [-]
I'm guessing there's no likelihood of a regular Clojure equivalent of this?
rockyj 1 days ago [-]
Nice! Now also get rid of the elephant in the room - "Google Closure Compiler" and then we can really celebrate.
Jach 1 days ago [-]
Is that something people want to get rid of? Back when I did some clojurescript people were pretty proud of being able to have it used automatically. What's the plan to get the same benefits? Or is the argument that the benefits aren't significant 15ish years on?
barrell 23 hours ago [-]
I would say the community is pretty evenly split between people who hate it, and people who find it practical. I don't see many people really championing it or being proud of it these days.
Well, technically I think most of the community in indifferent. But from the discourse about the topic, I feel like I see pretty even splits.
rockyj 23 hours ago [-]
Last i checked, it needed JVM (parts of the library are in Java). Given there are many JS minifiers and optimizers (tree shaking etc.) avaliable in JS itself in 2026, I do not know why we need this huge overhead.
hrrld 23 hours ago [-]
No, you're right, we don't want to get rid of it; it's great.
zerr 1 days ago [-]
For the moment thought the article was about CoffeeScript... But it already supports async/await :)
rpastuszak 1 days ago [-]
I can finally use this little brain worm that has lived in my head for more than a decade now: IcedCoffeeScript has existed for ages https://maxtaco.github.io/coffee-script/ since well before ES got it.
For the longest time, I recall the opposition to async/await support being twofold:
1. adding support would require deep changes across the CLJS compiler (theller, creator of shadow-cljs, once tried and concluded this)
2. macros from libraries like Promesa provided similar convenience
There were some other arguments brought up at the time (e.g. just use core.async, expression-oriented languages aren't a good fit with async/await, etc.), but they were usually specific to one person rather than something you'd see repeated in forums.
In the Clojurians Slack, borkdude once stated he wasn't convinced it'd be impractical to add support. It seems that he eventually took the time and made it happen. Extremely thankful for that.
edit: i'm in no way trying to diminish the value of this release, just pointing out how cool it is that you can get new language features before they are available in the host language by just adding a library to your dependencies. clojure is awesome!
Definitely. I was heavily using it and it worked: a few quirks but we did have async/await since more than a decade. I think I discovered it after watching a talk by David Nolen.
Since then I moved to minimal JavaScript on the front-end: SSE is one-way and that is beautiful. I'm glad to see many devs, from a great many different languages, now getting interested in SSE.
Here's a great, recent, talk by David Nolen called "A ClojureScript Survival Kit":
https://youtu.be/BeE00vGC36E
I cannot thanks David "Swannodette" Nolen enough for all the work he did on ClojureScript (and core.async) since its inception. And what's amazing in this talk is that he's actually excited at the idea that we may do away with ClojureScript and use pure Clojure (on the server-side) and server-side events, with just a tiny of JavaScript.
The real demo starts around 26:30. He shows a Webapp running on the client and how much resources it's using, then he shows the exact same Webapp running on the server and pushed one-way to the client using SSE. It is wild: resources usage drops to near zero.
YMMV but I find it easier to reason about my webapps and manage state now that I'm using a minimal DOM morphing lib: I used to have two REPLs (one for Clojure, one for ClojureScript) and lots of back-and-forth traffic and hard-to-track / reproduce state. Now everything is definitely snappier and way easier to reproduce.
I'm not saying SSE is going to work in every case though: YMMV. But in any case the video or at the very least the demo starting @ 26:30 is very much worth watching.
It balloons up the Js artifact, has no inherent error model, and transforms into state machine code that's hard to read/debug if something goes wrong. Plus, the `go` macro encourages overly-large functions, because it can't transform code outside its own sexpr.
As one Cognitect put it, "core.async is beautiful nonsense".
I'll pitch in here, as I've been doing a lot of thinking about this issue and ended up writing my own (tiny) tools for handling anomalies, modeled on the very well thought-out https://github.com/cognitect-labs/anomalies categorization.
This is actually a much wider problem and not specific to core.async. Handling anomalies is difficult. It used to be that you would have exceptions and errors which would be thrown, unwinding the stack. This pattern no longer works in asynchronous code, or code that needs to pass anomalies between the server and the client. In practical applications, an anomaly might need to be returned from a function, passed through a `core.async` channel, then thrown, unwinding the stack on the server side, then caught and passed to the client side over a WebSocket, and then displayed to the user there.
Solving this well is not easy. I think my toolkit, iterated and improved over the years, is close to what I need. But I'm pretty sure it wouldn't handle all the real-world use cases yet.
But again, this is not specific to core.async in any way.
[0]: https://github.com/IGJoshua/farolero
My status toolkit just extends the Cognitect anomalies to be statuses, adding ::failed (parameters correct, but could not perform request), ::ok, ::accepted and ::in-progress. It also adds a bunch of utility functions like status/?! (throws the parameter if it's anomaly, returns the parameter otherwise) and macros like status/-?> (threads if an expression is not an anomaly). That's it.
I deliberately avoid trying to do too much here.
I loved ztellman’s “everything must flow” talk on the topic.
Is the sudden buzz due to agentic coding? Does it rip through code faster with no type checking and fewer invalid syntax errors and reserved keywords to deal with? are we in for a sexp resurgence?
Most serious Clojure code bases I'm aware of invest heavily in their test suite so yes you can just add a skill to your AI that tells it the most effective way to use your test suite then send it to the races
Some of my colleagues let the agent interact with the REPL and they report faster performance because the agent is not paying the start up cost on every interaction, personally I've been lazy there its fast enough for me
As you've hinted at Clojure does have less bits that get in the way, everything is true except false and nil, the language does not have order precedence table the core language supports immutable and persistent data structures as default
Everything is an expression nothing is a mixture of operators and expressions map, reduce, filter are built in and expected in normal code
Code you wrote 10 years ago in Clojure will likely still work today the ecosystem and language authors treat breaking code as taboo
Of all the languages I've used its the least headache inducing and the most freeing in terms of expressing my ideas
Also the defacto reverse debugger Flowstorm is a programming dream
Its a lovely language if you want to be content
The flip side of that is most users take it for granted and don't talk about it much
There are also a lot of commercial Clojure programmers who do not understand the language and as a result not that happy, they often didn't willing choose it, probably not ready for it, I think most Clojurians should have gone through a decade of noticing things in their other languages they didn't like before using it
Rich Hickey the creator of Clojure does famously influential videos on software but that doesn't mean your colleagues have watched them or care
But in the end. Choose typed languages or dynamic languages with type hints if you are going for the AI route.
https://hypermedia.systems/
I came to the conclusion that the best frontend is no frontend.
https://blisswriter.app/
https://blog.nestful.app/p/how-we-dropped-vue-for-gleam-and
Congratulations on the release :-)
https://clojurescript.org/guides/promise-interop#using-promi...
core.async isn't going anywhere, if async/await works better than promise based implementation, core.async will get an update in it's .cljs parts
Well, technically I think most of the community in indifferent. But from the discourse about the topic, I feel like I see pretty even splits.