OSS updates September and October 2025

In this post I’ll give updates about open source I worked on during September and October 2025.

To see previous OSS updates, go here.

I’d like to thank all the sponsors and contributors that make this work possible. Without you, the below projects would not be as mature or wouldn’t exist or be maintained at all! So a sincere thank you to everyone who contributes to the sustainability of these projects.

Current top tier sponsors:

Open the details section for more info…

In this post I’ll give updates about open source I worked on during September and October 2025.

To see previous OSS updates, go here.

Current top tier sponsors:

Open the details section for more info about sponsoring.

Sponsor info

If you want to ensure that the projects I work on are sustainably maintained, you can sponsor this work in the following ways. Thank you!

Github Sponsors
The Babashka or Clj-kondo OpenCollective
Ko-fi
Patreon
Clojurists Together

Updates

The summer heat has faded, and autumn is upon us. One big focus for me is preparing my talk for Clojure Conj 2025, titled “Making tools developers actually use”. I did a test run of the talk at the Dutch Clojure Meetup. It went a bit too long at 45 minutes, so I have to shrink it almost by half for the Conj. The more I work on the talk the more ideas come up, so it’s challenging!

presentation at Dutch Clojure meetup

Of course I spent a ton of time on OSS the past two months as well. Some special mentions:

I’m pretty excited by Eucalypt, a remake of Reagent for Squint without React by Chris McCormick. It lets you build UIs with the Reagent API in less than 10kb of gzip’ed JS. The code was initially generated by an LLM, but now work is going into making the code base thoroughly tested and simplified where possible.
After studying Eucalypt’s code I figured that making an even more minimal Reagent-like by hand would be fun. This is where I came up with Reagami. The API looks like a hybrid between Reagent and Replicant. You can build apps with Reagami starting around 5kb gzip’ed.
Edamame got Clojure CLR support thanks to Ambrose Bonnaire-Sergeant.
SCI Clojure CLR support is underway. The sci.impl.Reflector code, based on clojure.lang.Reflector was ported to Clojure with the purpose that it would then be easier to translate to Clojure CLR.
Cljdoc chose squint for its small bundle sizes and easy migration off of TypeScript towards CLJS
Via work on Squint, I found a way to optimize str in ClojureScript (worst case 4x, best case 200x)

Here are updates about the projects/libraries I’ve worked on in the last two months in detail.

babashka: native, fast starting Clojure interpreter for scripting.

Bump to clojure 1.12.3
#1870: add .addMethod to clojure.lang.MultiFn
#1869: add clojure.lang.ITransientCollection for instance? checks
#1865: support reify + equals + hashCode on Object
Add java.nio.charset.CharsetDecoder, java.nio.charset.CodingErrorAction, java.nio.charset.CharacterCodingException in support of the sfv library
Fix nrepl-server completions and lookup op to be compatible with rebel-readline
Add clojure.lang.Ref for instance? checks
Bump SCI: align unresolved symbol error message with Clojure
Use GraalVM 25
Bump deps.clj to 1.12.3.1557
Change unknown or REPL file path to NO_SOURCE_PATH instead of <expr> since this can cause issues on Windows when checking for absolute file paths
#1001: fix encoding issues on Windows in Powershell. Also see this GraalVM issue
Fixes around java.security and allowing setting deprecated Cipher suites at runtime. See this commit.
Support Windows Git Bash in bash install script

SCI: Configurable Clojure/Script interpreter suitable for scripting

ClojureCLR support in progress (with Ambrose Bonnaire Sergeant)

edamame: configurable EDN and Clojure parser with location metadata and more

1.5.33 (2025-10-28)
Add ClojureCLR support (@frenchy64)

clj-kondo: static analyzer and linter for Clojure code that sparks joy.

Unreleased
#2651: resume linting after paren mismatches
2025.10.23
#2590: NEW linter: duplicate-key-in-assoc, defaults to :warning
#2639: NEW :equals-nil linter to detect (= nil x) or (= x nil) patterns and suggest (nil? x) instead (@conao3)
#2633: support new defparkingop macro in core.async alpha
#2635: Add :interface flag to :flags set in :java-class-definitions analysis output to distinguish Java interfaces from classes (@hugoduncan)
#2636: set global SCI context so hooks can use requiring-resolve etc.
#2641: fix linting of def body, no results due to laziness bug
#1743: change :not-empty? to only warn on objects that are already seqs
Performance optimization for :ns-groups (thanks @severeoverfl0w)
Flip :self-requiring-namespace level from :off to :warning
2025.09.22
Remove dbg from data_readers.clj since this breaks when using together with CIDER
2025.09.19
#1894: support destruct syntax
#2624: lint argument types passed to get and get-in (especially to catch swapped arguments to get in threading macros) (@borkdude, @Uthar)
#2564: detect calling set with wrong number of arguments
#2603: warn on :inline-def with nested deftest

squint: CLJS syntax to JS compiler

Support passing keyword to mapv
Inline identical? calls
Clean up emission of paren wrapping
Add nat-int?, neg-int?, pos-int? (@eNotchy)
Add rand
Fix rendering of null and undefined in #html
#747: #html escape fix
Optimize nested assoc calls, e.g. produced with ->
Avoid object spread when object isn’t shared (auto-transient)
Optimize =, and, and not= even more
not= on undefined and false should return true
Optimize code produced for assoc, assoc! and get when object argument can be inferred or is type hinted with ^object
Optimize str using macro that compiles into template strings + ?? '' for null/undefined
Fix #732: take-last should return nil or empty seq for negative numbers
#725: keys and vals should work on js/Map
Make map-indexed and keep-indexed lazy
Compile time optimization for = when using it on numbers, strings or keyword literals
Switch = to a deep-equals implementation that works on primitives, objects, Arrays, Maps and Sets
Fix #710: add parse-double
Fix #714: assoc-in on nil or undefined
Fix #714: dissoc on nil or undefined
Basic :import-maps support in squint.edn (just literal replacements, prefixes not supported yet)

reagami: A minimal zero-deps Reagent-like for Squint and CLJS

First releases

clerk: Moldable Live Programming for Clojure

Support evaluation of quoted regex
Support macros defined in notebooks
Bump cherry

cljs-str

More efficient drop-in replacement for CLJS str. This work was already upstreamed into CLJS, so coming near you in the next CLJS release.

unused-deps: Find unused deps in a clojure project

Support finding unused git deps

scittle: Execute Clojure(Script) directly from browser script tags via SCI

Fix SCI regression where interop on keywords like (.catch ...) was accidentally munched

Nextjournal Markdown

Add :start attribute to ordered lists not starting with 1 (@spicyfalafel)

cherry: Experimental ClojureScript to ES6 module compiler

Bump squint compiler common component and standard library
Bump other deps
Optimize =, str, not=
Support :macros option + :refer so you can use unqualified macros using compiler state (see macro-state-test)

deps.clj: A faithful port of the clojure CLI bash script to Clojure

Released several versions catching up with the clojure CLI

pod-babashka-go-sqlite3: A babashka pod for interacting with sqlite3

Add close-connection
Fix #38: add get-connection to cache connection
Fix potential memory leak
Better handling of parent process death by handling EOF of stdin
#25: use musl to compile linux binaries to avoid dependency on glibc

quickdoc: Quick and minimal API doc generation for Clojure

Fix extra newline in codeblock

Contributions to third party projects:

ClojureScript

Optimize str (4x worst case, 200x best case)
Make munge-str public

Selmer

Handle error for template without closing delimiter

clojure-lsp

Optimize :ns-groups handling by caching regex creation and usage

Other projects

These are (some of the) other projects I’m involved with but little to no activity happened in the past month.

Click for more details - [CLI](https://github.com/babashka/cli): Turn Clojure functions into CLIs! - [pod-babashka-fswatcher](https://github.com/babashka/pod-babashka-fswatcher): babashka filewatcher pod - [sci.nrepl](https://github.com/babashka/sci.nrepl): nREPL server for SCI projects that run in the browser - [babashka.nrepl-client](https://github.com/babashka/nrepl-client) - [fs](https://github.com/babashka/fs) - File system utility library for Clojure - [http-server](https://github.com/babashka/http-server): serve static assets - [nbb](https://github.com/babashka/nbb): Scripting in Clojure on Node.js using SCI - [sci.configs](https://github.com/babashka/sci.configs): A collection of ready to be used SCI configs. - [http-client](https://github.com/babashka/http-client): babashka’s http-client - [quickblog](https://github.com/borkdude/quickblog): light-weight static blog engine for Clojure and babashka - [process](https://github.com/babashka/process): Clojure library for shelling out / spawning sub-processes - [html](https://github.com/borkdude/html): Html generation library inspired by squint’s html tag - [instaparse-bb](https://github.com/babashka/instaparse-bb): Use instaparse from babashka - [sql pods](https://github.com/babashka/babashka-sql-pods): babashka pods for SQL databases - [rewrite-edn](https://github.com/borkdude/rewrite-edn): Utility lib on top of - [rewrite-clj](https://github.com/clj-commons/rewrite-clj): Rewrite Clojure code and edn - [tools-deps-native](https://github.com/babashka/tools-deps-native) and [tools.bbuild](https://github.com/babashka/tools.bbuild): use tools.deps directly from babashka - [bbin](https://github.com/babashka/bbin): Install any Babashka script or project with one command - [qualify-methods](https://github.com/borkdude/qualify-methods) - Initial release of experimental tool to rewrite instance calls to use fully qualified methods (Clojure 1.12 only) - [neil](https://github.com/babashka/neil): A CLI to add common aliases and features to deps.edn-based projects.

[tools](https://github.com/borkdude/tools): a set of [bbin](https://github.com/babashka/bbin/) installable scripts - [babashka.json](https://github.com/babashka/json): babashka JSON library/adapter - [speculative](https://github.com/borkdude/speculative) - [squint-macros](https://github.com/squint-cljs/squint-macros): a couple of macros that stand-in for [applied-science/js-interop](https://github.com/applied-science/js-interop) and [promesa](https://github.com/funcool/promesa) to make CLJS projects compatible with squint and/or cherry. - [grasp](https://github.com/borkdude/grasp): Grep Clojure code using clojure.spec regexes - [lein-clj-kondo](https://github.com/clj-kondo/lein-clj-kondo): a leiningen plugin for clj-kondo - [http-kit](https://github.com/http-kit/http-kit): Simple, high-performance event-driven HTTP client+server for Clojure. - [babashka.nrepl](https://github.com/babashka/babashka.nrepl): The nREPL server from babashka as a library, so it can be used from other SCI-based CLIs - [jet](https://github.com/borkdude/jet): CLI to transform between JSON, EDN, YAML and Transit using Clojure - [lein2deps](https://github.com/borkdude/lein2deps): leiningen to deps.edn converter - [cljs-showcase](https://github.com/borkdude/cljs-showcase): Showcase CLJS libs using SCI - [babashka.book](https://github.com/babashka/book): Babashka manual - [pod-babashka-buddy](https://github.com/babashka/pod-babashka-buddy): A pod around buddy core (Cryptographic Api for Clojure). - [gh-release-artifact](https://github.com/borkdude/gh-release-artifact): Upload artifacts to Github releases idempotently - [carve](https://github.com/borkdude/carve) - Remove unused Clojure vars - [4ever-clojure](https://github.com/oxalorg/4ever-clojure) - Pure CLJS version of 4clojure, meant to run forever! - [pod-babashka-lanterna](https://github.com/babashka/pod-babashka-lanterna): Interact with clojure-lanterna from babashka - [joyride](https://github.com/BetterThanTomorrow/joyride): VSCode CLJS scripting and REPL (via [SCI](https://github.com/babashka/sci)) - [clj2el](https://borkdude.github.io/clj2el/): transpile Clojure to elisp - [deflet](https://github.com/borkdude/deflet): make let-expressions REPL-friendly! - [deps.add-lib](https://github.com/borkdude/deps.add-lib): Clojure 1.12’s add-lib feature for leiningen and/or other environments without a specific version of the clojure CLI

Updates

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