As everyone knows, you are not a true lisper until you have written your own static site generator.
It gave me such a great high with how easy it was to add my own "templating engine" on top, implemented all using macros. The downside is that the crash came hard; there is so much more to a good static site generator such as optimizing the output, supporting scoped CSS, server-side rendering of SPA framework components, and of course integration with the Node ecosystem (for better or for worse there is just so much useful stuff). I have since moved over to Astro. It's still fascinating how far I was able to push my own SSG all by myself though.
Heh, inspired by hiccup, I ended up implementing my favorite Clojure templating library but in Nix, exactly for the purpose of static site generation :) Even have a nifty demo of how it looks for that, it basically looks/works the same as hiccup: https://emsh.cat/niccup/examples/blog/
With respect, this topic in particular has been beaten to death.
I too liked Clojure when I tried it some years ago (agreed on the composition and data structures; both are _great_). But the real value-add is in the runtime, not the syntax. Java has a solid runtime but it's not yet as good as Erlang's, maybe even not up to the standards of Golang -- I am talking concurrency / parallelism here (for memory management I have no doubts Java is very good). And I know: green threads and stuff. Well, call me when you can do what Erlang / Golang can do. Then I'll look again, very seriously too.
Programming language syntax scarcely matters. It does to some extent but we the programmers tend to over-romanticize it. The runtime and its properties are the much better thing to optimize for.
Clojure brings more than syntax though... there's an opinionated take on making all data structures immutable (as in, structural sharing [1]) by default. That's a huge difference in how you architect the program and debug it.
Have you tried Lisp Flavored Erlang [0]? I never got around to trying it out. I used Elixir for a couple of years, building web backends, and I truly loved the experience. I remember wanting to try out LFE but never got around to it before moving on to a different employer/stack.
I have and I did kind of like it but ultimately admitted to myself that I no longer want to use too niche or too new PLs. Elixir has a fairly solid ecosystem at this point and I am only going to switch to something even bigger (I already use Goland and Rust as well).
Love the idea of LFE but it needs a bigger ecosystem.
> Programming language syntax scarcely matters. It does to some extent but we the programmers tend to over-romanticize it. The runtime and its properties are the much better thing to optimize for.
I'm not sure I understand this argument. Java and Clojure share a runtime, but an idiomatic Java codebase is going to have a very different architecture and design to an idiomatic Clojure codebase. Conversely, a codebase written in Go may end up looking very similar to a codebase written in Java, despite using different runtimes.
To be clear, I'm not questioning your choice of runtime or language. I'm just curious why you think that "Programming language syntax scarcely matters", as to me that seems the same as saying "How a codebase is architectured and designed scarcely matters".
I don't see how the latter follows from the former? The former is much bigger and more abstract; syntax is just one of the vehicles to try and codify it.
F.ex. if you have an universal construct of green threads / fibers then 7 PLs could express it 7 different ways, yet underneath they'd all be the same.
The programming language informs the design of the system. As I said in my earlier comment, an idiomatic Java codebase is going to be designed very differently to an idiomatic Clojure codebase, even if they both intend to solve the same problem.
Scala has no immutability encoded in its runtime either (as it's the same as Java), but yet syntactically it's immutable in practice. Will the JRE technically allow a val to be edited through some third party thread inspecting your code and messing with memory? Sure. But it's not a reasonable fear in any real world environment, where I cannot remember, in 15+ years of professional scala, a case where anything I expected to be immutable (everything) to be mutated under me. Nowadays people using in in an FP style don't even think of the physical threads, as green thread libraries are taking care of all the scheduling.
So focusing on the runtime's guarantees doesn't seem like a practicality focused argument to me.
You are citing a commendable exception (Scala) to tear down a bigger argument which is not exactly a fair discussion.
Furthermore, if you trace my comments, you'll see that I had to choose PLs years ago (12+ to be precise). Things were quite different at the time. Java might have almost caught up today; back then we couldn't even be certain `synchronized` is stable all the time. Just saying.
Scala did very well then, judging by your words. I could probably offer a loose analogy to Typescript as well; while it does compile to JS underneath, they added a stricter layer that makes programming in it more deterministic and stable. (Not the same thing because my main point was "runtime" but hey, show me a perfect analogy.)
You are free to say your last sentence. I am free to disagree. My practice has shown me that runtimes bleed into syntax almost always. Exceptions exist, sure.
Thousands of share-nothing actors (fibers / green-threads) with first-class support for communication between them, for a start. Erlang/Elixir -- immutability as well.
When it comes to concurrency, what can golang's runtime do that is so special? When I tried it, it seemed like a worse version of Erlang's for people that prefer C style syntax. Depending upon your design space pervasive immutability is a huge boon too and golang doesn't have that but Clojure does - Erlang obviously having that and more.
I agree Golang is a worse version of OTP, no question about it, but if you are not allowed to code in Erlang/Elixir/Gleam (which sadly is 99.9% of the projects on the planet) then Golang is the next best thing.
It has footguns, sure, but with library support and discipline it can get you very far.
To me it's embarrassing that PLs still tout syntax and various other goodies, completely glossing over runtime. I might be missing something. But faux humble statements aside, I feel many others are the ones who miss something -- and that's the fact that doing stuff in parallel is a fact of life for 20+ years now and it's time all popular PL runtimes finally wake up to that fact.
If not, I am simply not considering them. And I am not saying that arrogantly though it sounds that way; there are some PLs that I _really_ liked and was almost heart-broken that I had to abandon them and not work professionally with them. But I have enough experience to know that runtime choice matters, a lot.
For the record, Racket was one of those PLs I abandoned. I know they started working on parallelism some years ago but I had to make a decision next week back then so, Elixir + Golang + Rust it is for me.
If they are, I have not heard about it (which does not mean much, I check Java once a year). And if they really are then I'd give Java a serious look again because it's a mature ecosystem that was gimped by ancient runtime decisions for literal decades.
As of Java 24 (Java 25 being an LTS) I'd say they are equivalent. You can use a virtual thread just like you use a regular thread and there's basically no handicaps or gotchas. In Java 21, when they were released, there is a gotcha that the pretty normal use of the `synchronized` keyword would pin a "carrier thread" which ends up blocking all virtual threads from running on that carrier thread.
Pinning can still happen in some much more rare cases, same with go. For example, FFI.
The memory usage, performance, etc are all go like. You can spawn millions of virtual threads with hardly and memory requirements and without overburdening the OS with context switches. The JVM also enjoys faster GC performance with virtual threads.
> Programming language syntax scarcely matters. It does to some extent but we the programmers tend to over-romanticize it. The runtime and its properties are the much better thing to optimize for.
But that really depends on what you're doing. For example if I'm not mistaken Amazon was run for a very long time on a Java backend. And so was GMail's backend (and back then GMail's frontend was, IIRC, Java converted to JavaScript using GWT).
And by "early Amazon" and "early GMail", we're already talking about massive scale. It's not as if the JVM got worse since then (as someone commented: a recent addition is that Clojure now use Java's virtual threads) and it's not as if it didn't scale.
So I'd say having Clojure on top of Java (for those using that Clojure: there's also ClojureScript, babashka, etc.) ain't really a problem, as long as you're fine with the occasional Java stacktrace and Java ecosystem (GP mentions that btw: that he's not familiar with Java and that, I think, can be a bit of an issue).
I'm not sure Clojure is about it's syntax: I like the focus on immutability / pure functions and I do really dig the REPL a huge lot. In addition to that something has to be said as to the incredible stability of the language and many of its libraries.
The big value add to me is that I can have a REPL and inspect, in dev (or in prod but that'd be wild), the app I'm working on. And manipulate it: redefining variables and functions etc. And it's not some hacky hot-reloading bolted on as an afterthought kludge: it's a real Lisp REPL. There's value in that IMO.
Elixir has all that _and_ Erlang OTP's amazing guarantees. Hence I landed on it.
Elixir also offers LiveBooks i.e. you can create pre-made recipes with which you directly remote into your staging / prod and do stuff.
All that with immutability and potentially 6 digits of actors / green threads with a share-nothing architecture.
---
RE: early Amazon / Google, sure. They made do with what they had and it was and still is a heroic effort. But can we agree that they succeeded _despite_ the numerous warts and defects of the PLs and their runtimes at the time? Not _because_ of them?
I feel that people latch onto the misleading "they succeeded with language X and are big, hence the language X is great" thing way too often. No. It's not true. The only thing that follows from "big company A made it big with language X" is: "company A has an amazing engineering team". Nothing else.
Once you learn Clojure's syntax and semantics, you're no longer bound to the JVM. There's ClojureScript (JS), ClojureCLR, ClojureDart, jank (C++), Basilisp (Python), babashka (SCI), and many others. This means that, if you don't know Java or don't like the JVM, you can likely use Clojure wherever you already feel most comfortable.
For the most part, any Clojure code which doesn't use host interop will work on all dialects. Clojure also has support for conditional code, depending on the current dialect.
If that’s your concern you don’t need to be concerned with any technical quality of any language. Just count job postings by language and learn the one with the highest value.
The functional paradigm is a bit uncomfortable at first, but it does make problem solving feel... different. I personally find OOP to be the most intuitive for large scale systems design, but that's just me.
Most models do not perform particularly well in Clojure, but OpenAI models fully utilize the power of the language. Subjectively, it kind of seems to match the personality. Data at https://gertlabs.com/rankings?provider=openai
Functional is far more comfortable to me. Trying to model all that state spread through out your program with no way to really isolate it or just reason about a small part of the program at a time, I find very stressful.
> I personally find OOP to be the most intuitive for large scale systems design, but that's just me.
At one point, I was the same. But after going functional in Clojure, I can’t imagine going back. Using maps nd just having common functions that transform data into different data is definitely the way to go. This is with your time:
https://youtu.be/aSEQfqNYNAc
> I personally find OOP to be the most intuitive for large scale systems design, but that's just me.
The beauty of Clojure shines through when you want to change something that cuts through a large part of a large project. If you are using mutable data, you may end up with many bugs from various pieces of code mutating objects inconsistently. With Clojure, if someone hands you data, you can't possibly break some distant piece of code by updating an object: it's just not possible because you only ever make fast, updated copies. The more complicated your codrbase gets, the more this benefit is realized.
I actually kind of think of it as an easier mechanism with similar outcomes to Rust's borrow checker. Only one piece of code ever owns the data so things end up much safer. However it is way easier to use IMHO because you just know that zero people own anything and everyone can read everything.
It also makes converting some code to be multi-threaded extremely easily and with some constraints guaranteeably correct.
Lots of dovetailing features neatly put together for both clarity and less bugs and more usable cores which are probably sitting idle.
Raw models aren't as effective with clojure as they are with typescript or python, but clojure has a superpower that most other languages don't have: the REPL! Specifically nREPL and the ecosystem around it.
An LLM is only as good as its feedback loop. If your LLM can actually test the code it writes, it's going to be much more effective. Static types are a form of feedback (if it can use the LSP), unit/integration tests are another.
Clojure has an exceptionally good repl. LLMs can eval any piece of any function. They can test out functions they aren't familiar with. They can fetch data, try out different arguments, try different approaches before committing to one. They can query a database (read-only connection, of course), look at the result, fetch data from an API, and stitch it all together. It can even hook into your running program and debug it from the inside out!!
It makes it so much more effective at using libraries or paradigms that it isn't trained on. In my experience, hooking an LLM up to the clojure repl lets it write WAY more complex stuff. I'm talking like 10x more complex programs with zero errors, cause it can literally try it out every little piece before putting it together. It's like watching a human programming. But like, really fast.
Sorry I get a little ranty when clojure + LLMs come up, because I don't think most people realize what they're missing out on. It's crazy stuff. It's also easy peasy if you use vscode. There's an extension called calva-backseat-driver that just hooks it all up for you. Gives copilot access to the repl, and I think it exposes an mcp if you want to give claude access too.
GPT 5.4+ models are extremely good at writing Clojure, agreed. In the agentic coding part of our benchmark, they do have access to the REPL via bash if they choose to use it. Filtered here: https://gertlabs.com/rankings?mode=agentic_coding
> I personally find OOP to be the most intuitive for large scale systems design, but that's just me.
Once you're more comfortable with it and want to try a typed functional programming language, I highly recommend checking OCaml (or SML, if you're into old school tech) and see how the Module Functors are applied, most software will look extremely over-engineered after you write a few functors. It's the feature I miss the most when coding in F# or Gleam, for instance.
What would you say is missing from Clojure for large-scale OOP design? As I understand, Clojure gives you OOP a la carte. Objects (via maps/records/structs), polymorphic dispatch (via multimethods/protocols/case), types (via Malli/TypedClojure), inheritance (via derived, isa?, etc), some encapsulation (via defn-/^:private)...
Not the person you're replying to, but have you tried TypedClojure? I've always thought clojure-with-types would literally be the perfect language, but I also read TypedClojure is more of a research project than a real language that you should use in prod.
No sorry, of the things I've listed, I'd never seen nor heard of a project that uses Typed Clojure, nor probably inheritance via dervied/isa?.
For static (partial) typing, I instead use Malli schemas. I do this for every larger Clojure program I make, because there's always something that needs paranoia, or it's handy to generate example data.
I might just be a simpleton -- I never had the resolve to try an ambitious project in Clojure. I was not aware that you could get full OOP though, what you are describing feels like yes technically possible but kind of a hack to get inheritance / no type hierarchy enforcement. I'm no expert on the language though
I actually disagree. Once you remove the cruft and crap of the involved syntax, good OOP design tends to look damn close to FP design. So I flip your point of view - class based OOP is the hack - despite not really using Clojure or FP in my dayjob or hobby projects anymore. Most fun I had with OOP was definitely Common Lisp though.
Not sure if I'm reading this right, but the "success rate" table for OpenAI models shows Clojure near the bottom. And if I switch provider to Anthropic, success rate for most languages, including Clojure, goes up dramatically.
Success rate includes syntax/compilation failures as well as environment rule violations, and is almost entirely from one-shot code generations. Percentile shows how well the working submissions perform.
In long horizon agentic coding evaluations, strong models fix the syntax and percentile and it becomes a direct comparison of which submissions per language performed the best on average. You can filter for that here: https://gertlabs.com/rankings?provider=openai&mode=agentic_c...
I found this to be one of the more interesting talks I've watched.
Like you (I think) - I love functional languages.
But there's a problem I can't really figure out how to articulate where they reach a level where they stop "just working" imo. Maybe it's just me being too dumb.
I wonder if the author is familiar with Smalltalk - it has a very small syntax. In some ways so does Lisp, in other ways it has more than every other language, depending on what you think about operators versus functions.
Other than that, I agree, CL is baroque yet needs some hole filling here and there.
> Lisp: everything is a list
But that's wrong. Not even a little. Unless you mean LISP 1.5...
> Too much syntax
Funnily, I'm mostly okay with the new vector/set/hash-table literals, my big problem and that of some other people is the use of vectors in macros/special operators instead of lists. `(let [a b] ...)` instead of `(let (a b) ...)` is _not_ okay.
As everyone knows, you are not a true lisper until you have written your own static site generator.
It gave me such a great high with how easy it was to add my own "templating engine" on top, implemented all using macros. The downside is that the crash came hard; there is so much more to a good static site generator such as optimizing the output, supporting scoped CSS, server-side rendering of SPA framework components, and of course integration with the Node ecosystem (for better or for worse there is just so much useful stuff). I have since moved over to Astro. It's still fascinating how far I was able to push my own SSG all by myself though.
I too liked Clojure when I tried it some years ago (agreed on the composition and data structures; both are _great_). But the real value-add is in the runtime, not the syntax. Java has a solid runtime but it's not yet as good as Erlang's, maybe even not up to the standards of Golang -- I am talking concurrency / parallelism here (for memory management I have no doubts Java is very good). And I know: green threads and stuff. Well, call me when you can do what Erlang / Golang can do. Then I'll look again, very seriously too.
Programming language syntax scarcely matters. It does to some extent but we the programmers tend to over-romanticize it. The runtime and its properties are the much better thing to optimize for.
Clojure brings more than syntax though... there's an opinionated take on making all data structures immutable (as in, structural sharing [1]) by default. That's a huge difference in how you architect the program and debug it.
[1] https://softwarepatternslexicon.com/clojure/core-concepts-of...
[0]: https://en.wikipedia.org/wiki/LFE_(programming_language)
Love the idea of LFE but it needs a bigger ecosystem.
I'm not sure I understand this argument. Java and Clojure share a runtime, but an idiomatic Java codebase is going to have a very different architecture and design to an idiomatic Clojure codebase. Conversely, a codebase written in Go may end up looking very similar to a codebase written in Java, despite using different runtimes.
As mentioned, I did like Clojure. I'd switch to it if it was running inside the Erlang runtime (like Elixir does).
F.ex. if you have an universal construct of green threads / fibers then 7 PLs could express it 7 different ways, yet underneath they'd all be the same.
So focusing on the runtime's guarantees doesn't seem like a practicality focused argument to me.
Furthermore, if you trace my comments, you'll see that I had to choose PLs years ago (12+ to be precise). Things were quite different at the time. Java might have almost caught up today; back then we couldn't even be certain `synchronized` is stable all the time. Just saying.
Scala did very well then, judging by your words. I could probably offer a loose analogy to Typescript as well; while it does compile to JS underneath, they added a stricter layer that makes programming in it more deterministic and stable. (Not the same thing because my main point was "runtime" but hey, show me a perfect analogy.)
You are free to say your last sentence. I am free to disagree. My practice has shown me that runtimes bleed into syntax almost always. Exceptions exist, sure.
I always wished clojerl took off.
It has footguns, sure, but with library support and discipline it can get you very far.
To me it's embarrassing that PLs still tout syntax and various other goodies, completely glossing over runtime. I might be missing something. But faux humble statements aside, I feel many others are the ones who miss something -- and that's the fact that doing stuff in parallel is a fact of life for 20+ years now and it's time all popular PL runtimes finally wake up to that fact.
If not, I am simply not considering them. And I am not saying that arrogantly though it sounds that way; there are some PLs that I _really_ liked and was almost heart-broken that I had to abandon them and not work professionally with them. But I have enough experience to know that runtime choice matters, a lot.
For the record, Racket was one of those PLs I abandoned. I know they started working on parallelism some years ago but I had to make a decision next week back then so, Elixir + Golang + Rust it is for me.
Pinning can still happen in some much more rare cases, same with go. For example, FFI.
The memory usage, performance, etc are all go like. You can spawn millions of virtual threads with hardly and memory requirements and without overburdening the OS with context switches. The JVM also enjoys faster GC performance with virtual threads.
Nothing wrong with that, it's a good thing that stuff is discovered anew [as opposed to being lost/forgotten], but it did bring a smile to me.
But that really depends on what you're doing. For example if I'm not mistaken Amazon was run for a very long time on a Java backend. And so was GMail's backend (and back then GMail's frontend was, IIRC, Java converted to JavaScript using GWT).
And by "early Amazon" and "early GMail", we're already talking about massive scale. It's not as if the JVM got worse since then (as someone commented: a recent addition is that Clojure now use Java's virtual threads) and it's not as if it didn't scale.
So I'd say having Clojure on top of Java (for those using that Clojure: there's also ClojureScript, babashka, etc.) ain't really a problem, as long as you're fine with the occasional Java stacktrace and Java ecosystem (GP mentions that btw: that he's not familiar with Java and that, I think, can be a bit of an issue).
I'm not sure Clojure is about it's syntax: I like the focus on immutability / pure functions and I do really dig the REPL a huge lot. In addition to that something has to be said as to the incredible stability of the language and many of its libraries.
The big value add to me is that I can have a REPL and inspect, in dev (or in prod but that'd be wild), the app I'm working on. And manipulate it: redefining variables and functions etc. And it's not some hacky hot-reloading bolted on as an afterthought kludge: it's a real Lisp REPL. There's value in that IMO.
Elixir also offers LiveBooks i.e. you can create pre-made recipes with which you directly remote into your staging / prod and do stuff.
All that with immutability and potentially 6 digits of actors / green threads with a share-nothing architecture.
---
RE: early Amazon / Google, sure. They made do with what they had and it was and still is a heroic effort. But can we agree that they succeeded _despite_ the numerous warts and defects of the PLs and their runtimes at the time? Not _because_ of them?
I feel that people latch onto the misleading "they succeeded with language X and are big, hence the language X is great" thing way too often. No. It's not true. The only thing that follows from "big company A made it big with language X" is: "company A has an amazing engineering team". Nothing else.
For the most part, any Clojure code which doesn't use host interop will work on all dialects. Clojure also has support for conditional code, depending on the current dialect.
This is one of Clojure's superpowers.
I’m not quite sure what this means. How is it different/worse than all parens..?
fyi I use paredit and just hit ) and it moves me past any kind of paren/bracket. But even without that you can just hit left and right..?
Most models do not perform particularly well in Clojure, but OpenAI models fully utilize the power of the language. Subjectively, it kind of seems to match the personality. Data at https://gertlabs.com/rankings?provider=openai
At one point, I was the same. But after going functional in Clojure, I can’t imagine going back. Using maps nd just having common functions that transform data into different data is definitely the way to go. This is with your time: https://youtu.be/aSEQfqNYNAc
The beauty of Clojure shines through when you want to change something that cuts through a large part of a large project. If you are using mutable data, you may end up with many bugs from various pieces of code mutating objects inconsistently. With Clojure, if someone hands you data, you can't possibly break some distant piece of code by updating an object: it's just not possible because you only ever make fast, updated copies. The more complicated your codrbase gets, the more this benefit is realized.
I actually kind of think of it as an easier mechanism with similar outcomes to Rust's borrow checker. Only one piece of code ever owns the data so things end up much safer. However it is way easier to use IMHO because you just know that zero people own anything and everyone can read everything.
It also makes converting some code to be multi-threaded extremely easily and with some constraints guaranteeably correct.
Lots of dovetailing features neatly put together for both clarity and less bugs and more usable cores which are probably sitting idle.
An LLM is only as good as its feedback loop. If your LLM can actually test the code it writes, it's going to be much more effective. Static types are a form of feedback (if it can use the LSP), unit/integration tests are another.
Clojure has an exceptionally good repl. LLMs can eval any piece of any function. They can test out functions they aren't familiar with. They can fetch data, try out different arguments, try different approaches before committing to one. They can query a database (read-only connection, of course), look at the result, fetch data from an API, and stitch it all together. It can even hook into your running program and debug it from the inside out!!
It makes it so much more effective at using libraries or paradigms that it isn't trained on. In my experience, hooking an LLM up to the clojure repl lets it write WAY more complex stuff. I'm talking like 10x more complex programs with zero errors, cause it can literally try it out every little piece before putting it together. It's like watching a human programming. But like, really fast.
Sorry I get a little ranty when clojure + LLMs come up, because I don't think most people realize what they're missing out on. It's crazy stuff. It's also easy peasy if you use vscode. There's an extension called calva-backseat-driver that just hooks it all up for you. Gives copilot access to the repl, and I think it exposes an mcp if you want to give claude access too.
Once you're more comfortable with it and want to try a typed functional programming language, I highly recommend checking OCaml (or SML, if you're into old school tech) and see how the Module Functors are applied, most software will look extremely over-engineered after you write a few functors. It's the feature I miss the most when coding in F# or Gleam, for instance.
What would you say is missing from Clojure for large-scale OOP design? As I understand, Clojure gives you OOP a la carte. Objects (via maps/records/structs), polymorphic dispatch (via multimethods/protocols/case), types (via Malli/TypedClojure), inheritance (via derived, isa?, etc), some encapsulation (via defn-/^:private)...
For static (partial) typing, I instead use Malli schemas. I do this for every larger Clojure program I make, because there's always something that needs paranoia, or it's handy to generate example data.
In long horizon agentic coding evaluations, strong models fix the syntax and percentile and it becomes a direct comparison of which submissions per language performed the best on average. You can filter for that here: https://gertlabs.com/rankings?provider=openai&mode=agentic_c...
I found this to be one of the more interesting talks I've watched.
Like you (I think) - I love functional languages.
But there's a problem I can't really figure out how to articulate where they reach a level where they stop "just working" imo. Maybe it's just me being too dumb.
Tcl: everything is a string
Lisp: everything is a list"
Python: {"everything":"dictionary"}
Eh? That's completely lifted from CL (https://www.lispworks.com/documentation/HyperSpec/Body/t_seq...). Same for AREF/NTH, there's ELT.
Other than that, I agree, CL is baroque yet needs some hole filling here and there.
> Lisp: everything is a list
But that's wrong. Not even a little. Unless you mean LISP 1.5...
> Too much syntax
Funnily, I'm mostly okay with the new vector/set/hash-table literals, my big problem and that of some other people is the use of vectors in macros/special operators instead of lists. `(let [a b] ...)` instead of `(let (a b) ...)` is _not_ okay.
Is (let (a b) …) even valid clojure?