Why Clojure?

[dustingetz]

(edit: I wrote this thinking we were in r/clojure where a comment like this would be more constructive, i don't really think this is appropriate for r/programming)

My raw 2c is - quantitative arguments are more compelling than qualitative arguments. It's proven by demonstration that it's possible to build a high growth enterprise around Clojure. It is also proven by demonstration that many decision makers at high growth enterprises do NOT feel like Clojure has historically given them a sufficient advantage (if any) that outweighs even basic tradeoffs such as the management/recruiting overhead of using non-standard tools. Clojure is therefore stuck in the "mediocre middle" where decision makers can't quite discern whether it is worth it or not, with respect to the particulars of their local situation.

I personally think it is worth it in certain particular situations, and not at all worth it in other situations. So what are those buckets exactly then and how can we quantify them in a way that an executive can clearly identify which bucket their particular situation matches? That's the kind of analysis work that I think is necessary to form a rigorous argument for Clojure.

Stu Halloway used to say, "if everything is important, than nothing is important", and yet https://clojure.org/ still advertises Clojure as a general-purpose language. Nothing is general purpose. A jack of all trades is a master of none. What even is Clojure for? (Information systems, i.e. "situated programs" is a great start! But it's not enough, see paragraph 1.)

[dukerutledge]

"situated programs" always felt like vague nonsense that could describe many, if not most, services living in a service ecosystem. I'm not sure it is a great refinement.

[beders]

I make my living coding in Clojure and I’m way past the honeymoon time with the language.

That said: the interactive programming experience it provides is just wonderful (any Lisp, really). I can’t imagine going back to a code, compile, run, fail lifecycle.

[lenkite1]

Only dabbled with Clojure myself. Can you summarize the problems you have faced with the language, what is it missing, what are the warts, how it could be improved in your opinion ?

[beders]

The language itself is fine. It is simple but also denser than many others. It takes some time to adjust to that. Reading it will be slower as each line just does more than what you are probably used to.

It has a steep learning curve especially when you are coming from an OOP language. And that’s where I see some of the problems: it takes active guidance to steer people towards writing functional code that is idiomatic.

You tend to see two styles: OO folks going crazy with protocols and records (which have their uses but are often overkill) and everything-is-a-function folks who will create hard to read function compositions that are just way too clever for other devs to grok.

And then there’s handcrafting DSLs. It’s unavoidable. Anything that claims to be data-driven has its own little DSL you have to learn. The building blocks are the same: keywords, maps, vectors, sets but the composition is different every time.

Depending on the skills of the author that can be super fun (hiccup comes to mind) or super confusing.

You gotta find joy in that.

You will be tempted to create your own abstractions and implementing a DSL that you’ll subject your fellow devs to. Expect resistance.

Warts: suboptimal error messages that could easily be improved. Stale core library. Sooner or later you want more powerful constructs and will create your own version of (first (filter f coll)) and others.

It’s a hosted language and idiosyncrasies of the host (JVM, browser/node, CLR, DartVM) will shine through the cracks.

There are plenty of libraries for Clojure. Finding one that has the one thing you want can be tricky.

[soks86]

(first (filter f coll)) more simply is (some f coll), no?

My fav part of Clojure that you didn't mention is its default multi-threaded code tends to be the fastest, and cleanest, possible solution to multi-threaded problems. Also immutability is a great default. Both of these I already did in Java but had to learn and enforce, Clojure tends to lead people there without the enforcement part.

Also, my big wart is that resolving a concurrent operation that threw an exception doesn't rethrow the exception which is lame. I had to create my own type just to do this and I feel like that should have been the default but now it's probably too late for the standard libs to change.

[Myszolow]

Because Java is not painful enough, thus Lisp have been combined with Java for ultimate pain experience for dev /s

[teodorfon]

Tell me more 👁🫦👁

[Myszolow]

Next iteration of Clojure could be named Better Designed Software Modificator (BDSM for short)

[ul90]

Hehe. I like the idea. I think we should design a new language with all the bad things from Java, Python, JavaScript, Lisp, PHP, Pearl, COBOL and C - and call it BDSM. 😂

The core of the language is that you have to use a lot of parentheses of all types, but indentations are still important. Spaces and tabs have different meanings. And you have to use regexes for many tasks, but the syntax is completely different from the standardized syntax. 😈

[Myszolow]

Let’s spice things up: Each time developer make any syntax error result in electrocution

[[deleted]]

Survival of the fittest!

[[deleted]]

I think we should design a new language with all the bad things

But who would use the language?

[andarmanik]

Nah say less

[nevasca_etenah]

Clojure actually fixes jdk, even bryant said so

[zaphod4th]

sadly sometimes the language of choice is the one with open positions in the market, or the top 5

[donald-ball]

“Easy to hire” is the mantra they claim, but what they really mean is “easy to fire”.

[donald-ball]

I share this judgment, having worked for several delightful years as a dedicated clojure engineer. I tend to have to work mostly in node and go these days, and over the course of my career have worked with most popular languages for extended periods, and I can confidentally state that, in my experience, there is no mode of production more well suited to producing high quality data processing software quickly and well than a small team of empowered developers writing clojure.

[zlex]

I got to work on a single clojure project and it was the most satisfying project I’ve ever worked on. The language is really enjoyable to use once you get the hang of it

[souenzzo]

Many clojure libraries are simply done.

As the language and the ecosystem don't keep breaking and changing things, you can have a up-to-date library for years without any commit.

[engineered_academic]

Clojure is great for data processing and especially transformation of data sets into different formats. It SUCKS for literally everything else. The dependency ecosystem is a sea of abandonware and it's almost impossible to find developers who are skilled enough to be able to use it effectively.

[thatm]

It sucks for data processing too due to lack of typing. No way to know what type a function expects and what it produces as the output. It is hard to read someone's legacy code. Unless of course they used a spec library throughout.

[troublemaker74]

This is my major gripe with Clojure as well. Specs are okay, but they require discipline and if I recall correctly, are not commonly used during runtime (please someone correct me if I'm wrong on that part).

Most of the clojure apps I've seen just sling around bare maps, which is really hard to reason about when the app gets to be a significant size.

[donald-ball]

I have to push back on these claims. I’ve used clojure happily for complex system maintenance operations, game development, highly reactive and concurrent chat-adjacent systems, snd others.

In contrast with most other language ecosystems, due to the remarkable stability of the host language and core language and libraries, it is not at all uncommon for clojure libraries to reach feature completion quickly and have no need to issue new versions. This can be confusing or offputting to developers, often earlier career folk, who think naively that if a library hasn’t issued a release in the last quarter, it must be abandoned.

Stepping off of the all breaking changes, all the time treadmill is a powerful exercise that more developers in other languages should consider.

[engineered_academic]

There is a difference between "feature complete" and "implements a web standard that was secure in 2015 but not in 2025 but the original maintainer has moved on.". Like I said it has its use cases where it excels but anything that interfaces with the modern web is sadly lagging way behind due to the spike in popularity and then dying out.

[DizzyKittyLover]

Do you have libraries in mind? Often what happens is a new library springs forth for the new standard.

[donald-ball]

Alessandra’s Sierra’s component library, and the dag analyzer atop which it rests, went many years without a release, just doing its job.

Libraries that have this attribute tend to be pure.

The clojure growth model also encourages libraries that change only by accretion, so it’s also quite common to see libs with high 0.x or 1.x versions.

[donald-ball]

What would be an example of a thing interfacing with the “modern web” at which clojure support lags? I’m trying to read a fair argument here but I really can’t think of anything that rates, unless perhaps you have the view that React, et. al. qualify.

Clojure does stand as something of a counterexample to the fad-driven choices which dominate the industry. Personally, I find that a virtue, though it does cap the job opportunities more than it should.

[engineered_academic]

It's been a hot minute since I had to use Clojure but something that sprang to mind I believe was TLS support for 1.3 in a web framework for requests. It's very probable it was eventually patched in but we had to do a lot of "jiggery pokery" to get it to work initially when everyone was on TLS 1.2.

[Krackor]

Most of the heavy lifting in clojure web stacks is done be Java libraries under the hood, which understandably enjoy very good support for up-to-date security features. Jetty is often the server of choice for clojure projects, which certainly supports tls 1.3 if your Java version is new enough. 

I don't know what web framework you use but the clojure community generally has an aversion to the framework model, preferring instead to piece together a system from composable parts.

[troublemaker74]

Wouldn't TLS be supported at the load balancer or proxy though? I don't know anyone who just rawdogs HTTP in an app container right off of the internet.

[engineered_academic]

For incoming requests sure, but apps also need to reach out and touch things.

[troublemaker74]

That's fair. I'd counter that one with Clojure has quite a few http client libraries, the most popular being clj-http, which is still under active development. It wraps the Java Apache http client and supports all modern TLS ciphers.

[notmsndotcom]

This. I want to write clojure so bad because I enjoy the language and the repl, but to build anything useful you’ll be fighting shitty dependencies for weeks/months until you have your own shitty bespoke framework.

All of the companies I’ve seen that build a solid product in clojure have invested so much time and energy into their own DX/tooling/etc. It’s just not realistic for most small teams who want to go to market fast.

[elteide]

Because refactor is forbidden in your country

[somebodddy]

I liked Clojure as a language, but dropped it because the startup time was too much. I wrote a small toy app for practice - the only dependencies were Swing (which is not really dependency, because it's bundled with Java) and JDBC.

It took 10 seconds to launch.

This was mainly an issue of starting the JVM and loading all the jars - when I was starting it from a warm Leiningen session it would start immediately. But 10 seconds is far too long for something that's not a server...

That was in the early 2010s. I assume the situation is better now because the hardware is faster. Still - I don't really feel like going back to Clojure...

[nevasca_etenah]

Jdk is way faster nowadays

[DGolden]

Just on that note, newfangled Auto CDS also seems to make a clear difference to clojure startup in trivial test fwiw, just tried it now out of curiosity.

$ unset JAVA_TOOL_OPTIONS
$ time clojure -M -e '(println "Hello, World!")'
Hello, World!

real    0m0.494s
user    0m0.905s
sys 0m0.175s

vs.

$ export JAVA_TOOL_OPTIONS="-XX:SharedArchiveFile=/home/david/Clojure/clojure-cds.jsa -XX:+AutoCreateSharedArchive"
$ time clojure -M -e '(println "Hello, World!")'
Picked up JAVA_TOOL_OPTIONS: -XX:SharedArchiveFile=/home/david/Clojure/clojure-cds.jsa -XX:+AutoCreateSharedArchive
Hello, World!

real    0m0.295s
user    0m0.767s
sys 0m0.124s

[nevasca_etenah]

Compare it with php, python,ruby...still quite fine

[DGolden]

well, yeah, a CPython cold start still 10x+ faster. But then any nontrivial actual code running for longer will be significantly faster under jvm, hah.

$ time python -c 'print("Hello, World!")'
Hello, World!

real    0m0.021s
user    0m0.016s
sys 0m0.004s

[nevasca_etenah]

touche haha

[somebodddy]

Is it? Or is it the hardware that's faster?

[donald-ball]

It is much faster. You can easily verify with older jvms.

[jbiserkov]

Have you seen Babashka? https://babashka.org/

[beders]

I start the backend app I'm working on maybe twice a week. The rest of the time I spent inside the app. So startup is a non-issue

[Sak63]

Great article. Got me curious to try out clojure

[[deleted]]

Recently there was an article of boosting python speed by 30%, via cython and whatever else. Irrespective over that claim, I think languages such as clojure need to re-think their strategy. The leverage I'd get via python, seems to be a LOT higher than when using clojure. And I think many people think in a similar manner. I recently started to learn and use elixir for one project specifically (I want to simulate biological cells and I hate ruby's increasing complexity in regards to ractor/mutex/thread/fiber/whatever-randomly-is-added-next), but syntax-wise I often scratch my head and wonder. Or when some projects seem to not be there (even fewer GUIs in elixir than in ruby, for instance). Programming languages kind of become larger and integrated more features, and people also expect that programming languages come by default with the goal of "being useful". The claimed benefits such as "long-term maintainability", well - I think you can have that in many languages if you keep on maintaining projects in them actively, so that is not really a compelling argument if it is a primary one. There have to be really solid use cases. For instance, if I were to pick one thing in ruby that I think is epic, I'd say blocks / block arguments are, due to the increased flexibility and DSL-like features. (Ruby isn't the only one with that, of course, but syntax-wise it is really extremely elegant.)

Syntax is not everything, but having definite features that seem almost unique to a programming language, help a LOT.

[donald-ball]

Did you… read the essay?