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Jolt: Clojure compiler implemented with Chez Scheme
- mark_l_watson 2mo agoI just saw this - works great to build small self contained apps. (I just tested on macOS, also supports Linux).
- mark_l_watson 2mo agoClojure hosted on Chez Scheme (same as Racket). So cool. I tried building a standalone executable for the Chess game in my Clojure book using "jolt build -m chess-game.cli -o chess_jolt" and it simply worked great. I tried again with a datomic demo and it needed the source code to the open source version of datomic, so I need to do some work on that.
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- eggy 2mo agoCurious about the executable size and performance. Mark, you started me on AI with your, "Common LISP Modules: Artificial Intelligence in the Era of Neural Networks and Chaos Theory". I have never been able to fully leave Lisp behind. I'll have to try this on my linux box. What's your take on using jolt practically for work vs. learning? Thanks!
- mark_l_watson 2mo agoThanks for the kind words. I just built the Chess example in my Clojure book and the executable was a tiny 18M.
- eggy 2mo agoThank you! How about performance? Do you see Jolt evolving into something more useable for real work, or is it too niche and not capable enough? I always loved Racket. How does Jolt compare? I'll give it a try this weekend.
- ivanjermakov 2mo agoJolt Physics: https://github.com/jrouwe/JoltPhysics https://github.com/jrouwe/JoltPhysics
- eggy 2mo agoWhat does this have to do with Jolt, the Clojure compiler other than in name? Is there a port to Clojure or other connection?
- Ohentis 2mo agoI think the name being the same is worth bringing up. Ideally you would avoid name collisions with big projects but admittedly it does happen all the time.
- pjmlp 2mo agoThere are other collisions, like Jolt computer, Dr Dobbs Jolt awards. However to be fair, none of it came to mind when I saw the title.
- eggy 2mo agoYes, and people seem to leave context out of it nowadays, which usually makes it a moot point. When searching I would put "Jolt Chez" or "Jolt Clojure" to get relevant hits. There is a Jolt energy drink too, popular among techies, or it was...
- yogthos 2mo agoAuthor here, glad to answer any questions about Jolt.
- micro2588 2mo agoAwesome work, have you looked into using Racket's fork of Chez? It supports some additional extensions and architectures from base Chez that would seem to beneficial as a compiler target, at least that was the case a couple years ago.
- yogthos 2mo agoThanks, and I have good news on that front actually. I recently factored out a portable Scheme layer and got Jolt to compile against Gambit as a backend. And given that Racket is basically an extension of Chez, it should be trivial to build against it now. I wrote up a post on how this works here https://yogthos.net/posts/2026-08-07-portable-jolt.html https://yogthos.net/posts/2026-08-07-portable-jolt.html
- iainctduncan 2mo agoCongrats, this is awesome! I have followed your writing and have your book, so was excited to see this was you. I have one question, can one drop into Scheme the way one can call Java in clojure, or is one totally firewalled from the underlying Scheme implementation? Great to see Gambit getting love too. Gambit and Chez are amazing achievements.
- tosh 2mo agoit's good to have even more (and more slim!) ways to run Clojure (not just JVM and JavaScript runtimes)
- kccqzy 2mo agoI understand some don’t like having a JVM, but for running in the browser, what does Jolt on Gambit offer over plain ClojureScript?
- yogthos 2mo agoOh I would definitely recommend ClojureScript or Squint for running in the browser. Using Gambit to compile to Js was really just an illustration of how Jolt has a portable layer that can be compiled to a completely different Scheme backend. I don't really intend to compete with the existing frontend solutions because you really want to keep your dialect as light as possible to minimize the size and friction with the existing Js ecosystem.
- nucleogenesis 2mo agoWhat a wonderful excuse to dive back into Clojure! This looks fantastic. I wonder what neat stuff might be made in Clojure thanks to a C FFI that wasn’t doable on top of the JVM.
- busterarm 2mo agoI've been diving back into Clojure just recently and this will be something I'll be trying to use immediatley.
- pjmlp 2mo agoNote that nowadays with Panama, there are more FFI opportunities in JVM implementations as well. Although it is rather verbose, and it is easier to have a C header and run jextract on it, instead of the manual boilerplate. No idea how well AI tooling would manage.
- ramblurr 2mo agoCoffi is a great library that makes Panama FFI/FFM painless without interop. https://github.com/IGJoshua/coffi https://github.com/IGJoshua/coffi For example look at this arc from sqlite4clj https://github.com/andersmurphy/sqlite4clj/blob/master/src/sqlite4clj/impl/api.clj https://github.com/andersmurphy/sqlite4clj/blob/master/src/s... it's very elegant. (Also can plug my own libvips wrapper using coffi https://github.com/outskirtslabs/vips https://github.com/outskirtslabs/vips) Using FFI/FFM "vanilla" with java interop is also viable, and in my experience the SOTA models do just fine with it (with or without jextract).
- pjmlp 2mo agoGreat overview, thanks!
- pjmlp 2mo agoNice to see further adoption from Chez Scheme. Have to give it a try.
- pmkary 2mo agoHow many years have it been there? My memory reminds me of Jolt but I very hardly remember what was it, all I remember is that it was a LISP.
- taolson 2mo agoYou're probably thinking of Ian Piumarta's COLA project (Combined Object Lambda Architecture), which had parts named after cola soft-drinks (Coke was a lisp-like language, Pepsi was a Smalltalk-like language, and Jolt was an early implementation of Coke): https://www.piumarta.com/software/cola/ https://www.piumarta.com/software/cola/
- phtrivier 2mo agoHow much does this overlap / complements something like jank ? [1] How much "production ready" / "battle tested" would this be ? (Not to start a flame war, I'm genuinely curious about the differences.) [1] https://github.com/jank-lang/jank https://github.com/jank-lang/jank
- yogthos 2mo agoI have a slightly different goal from Jank because my goal is to provide a runtime that supports existing Clojure libraries. I've spent the time to map out Java standard library APIs that popular libraries use and to create shims on top of Chez that allows them to run seamlessly. You can see a list of libraries that are fully tested and officially supported here. https://jolt-lang.github.io/docs/libraries.html https://jolt-lang.github.io/docs/libraries.html On top of that, I expose the API for creating shims in user space, so people can easily add their own for the libraries they want to use that might not be covered in the core. And I leverage this functionality myself to create libraries for JDBC layer or crypto that rely on doing FFI to shared system libraries that aren't part of the core runtime. In terms of how production ready Jolt is, it's still fairly new obviously, so there will inevitably be bugs. However, it already passes full https://github.com/jank-lang/clojure-test-suite https://github.com/jank-lang/clojure-test-suite from Jank, and has its own conformance corpus https://github.com/jolt-lang/jolt/blob/main/test/chez/corpus.edn https://github.com/jolt-lang/jolt/blob/main/test/chez/corpus... which is a superset of that. On top of that, I'm now able to run original test suites for the libraries I support and compare them with JVM outputs to ensure there aren't unintended divergences. The other side of it is the benchmark harness which I use to ensure performance stays reasonably close to the JVM, in most cases it's within 1.x, and the worst case is around 6x right now. https://github.com/jolt-lang/jolt/tree/main/bench https://github.com/jolt-lang/jolt/tree/main/bench So, Jolt basically aims to be a drop in JVM replacement for running existing Clojure code.
- adz5a 2mo agoBut isn't it kind of a one way street? We can extract clojure code from the JVM but then we cannot use its ecosystem anymore, which kinda feels like a los. Since we can use (n)REPL in all ecosystems (jvm, browser, node etc...), could we use it or a variation to have interop?
- smartmic 2mo agoBesides this and jank, there is also Janet; playing in the league of Lisp to standalone binaries. It’s also cool! https://janet-lang.org/ https://janet-lang.org/
- geokon 2mo agoI spent a couple of days digging in to Janet and what surprised me was how even though at a surface level it resembles Clojure, under the hood its actually quite radically different. It has a lot of very interesting ideas going on, though ultimately i didnt end up using it (i need my persistent datastructures and seq col abstractions) It feels very minimal and scheme-y and very different from anything ive used before. Definitely worth exploring
- dharmatech 2mo agoSee also lg which is a clojure implemented in go: https://github.com/nooga/let-go https://github.com/nooga/let-go Fun fact. It also runs on plan9: https://github.com/nooga/legmacs/issues/1 https://github.com/nooga/legmacs/issues/1
- phforms 2mo agoAs a more-or-less neutral observation (I still kind-of like the project): What I find curious - perhaps a sign of these times: After just 2-3 months in development (judging from the repo commits, obviously I have no insight into what came before), the developer already communicates Jolt as a feature-complete, polished (perhaps even mature) Clojure dialect with multiple Jolt-adapted libraries from JVM-Clojure, FFI, Fibers, already with a professional looking and marketing-focussed website, detailled documentation, nREPL support, etc. Things I wouldn’t expect so soon from a language developed (mostly?) by a single person in such an early release stage. I don’t know how to get a feeling about the actual state of projects like this anymore, so I always remain a bit suspicious. In Clojure, there is the (Rich Hickey inspired) design philosophy of “hammock driven development”, where we don’t rush things, let them simmer while lying in the hammock, sleeping on them, taking a walk, etc. Makes me wonder if projects like this are too rushed these days without thinking things through, discussing design decisions and getting ideas from other people, letting them mature over time. This isn’t specifically about Jolt (I don’t know much about it or its creator), it just inspired the thought, especially when comparing it to projects like Jank which has been years in development, with lots of feedback from the community and Clojure core maintainers as input.
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- davexunit 2mo agoYou're right to be suspicious: it's slop.
- iLemming 2mo agoThis is such a disingenuous, childish, immature and ignorant take - I can't even remain calm without getting angry. Have you ever, kids, tried building anything useful? Anything practical, anything that actually works, anything beneficent? With or without AI? Well, if you have in fact ever tried, perhaps you'd know that building reasonably complex software remains a difficult, challenging, unappreciated work. With or without the help of any tooling. AI-assistants included. Maybe try building something good first. Earn your right to throw the first stone, come engaged, come prepared, ask questions. What you're doing is a fucking slop. Human slop of ignorance. Worst kind.
- davexunit 2mo agoThis appears to be vibecoded but not disclosed as such. 2k commits from a single author starting from June 1st with really long commit messages and source code comments. The GitHub org has 19 additional projects that are all recently created. edit: Yup, found a very long blog post that says it's made with LLMs near the end https://yogthos.net/posts/2026-07-02-jolt.html https://yogthos.net/posts/2026-07-02-jolt.html
- xedrac 2mo agoI think the author has been very open about the use of LLMs. And while I am very wary of LLM slop, this is one use case where it makes complete sense to utilize them to the fullest. A Clojure implementation already exists for LLMs to reference, and tons of test cases to verify behavior. It doesn't get better than that for LLM usage.
- fulafel 2mo agoVibecoding means you don't pay much attention to the code, not the case here.
- nemoniac 2mo agoDoes it have tail-call optimization? I scanned the docs but don't see it mentioned. Presumably basing Jolt on Chez removes the limitation of the JVM? It could be an interesting selling point.
- yogthos 2mo agoYup, Jolt has TCO inherited from Scheme
- JerboaScheme 2mo agoChez Scheme is highly underrated! Jolt is amazing work. I also have been using it for Jerboa, a Gerbil Scheme compatible language. https://jerboa.sh https://jerboa.sh 8,820,174 lines of 100% vibe coded code.