In this post I'll give updates about open source I worked on during November and December 2025.

To see previous OSS updates, go here.

Sponsors

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:

• Clojurists Together
• Roam Research
• Nextjournal
• Nubank

Open the details section for more info about sponsoring.

Updates

Clojure Conj 2025

Last November I had the honor and pleasure to visit the Clojure Conj 2025. I met a host of wonderful and interesting long-time and new Clojurians, many that I've known online for a long time and now met for the first time. It was especially exciting to finally meet Rich Hickey and talk to him during a meeting about Clojure dialects and Clojure tooling. The talk that I gave there: "Making tools developers actually use" will come online soon.

Babashka conf and Dutch Clojure Days 2026

In 2026 I'm organizing Babashka Conf 2026. It will be an afternoon event (13:00-17:00) hosted in the Forum hall of the beautiful public library of Amsterdam. More information here. Get your ticket via Meetup.com (currently there's a waiting list, but more places will come available once speakers are confirmed). CfP will open mid January. The day after babashka conf, Dutch Clojure Days 2026 will be happening. It's not too late to get your talk proposal in. More info here.

Projects

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 process to 0.6.25
  • Bump deps.clj
  • Fix #1901: add java.security.DigestOutputStream
  • Redefining namespace with ns should override metadata
  • Bump nextjournal.markdown to 0.7.222
  • Bump edamame to 1.5.37
  • Fix #1899: with-meta followed by dissoc on records no longer works
  • Bump fs to 0.5.30
  • Bump nextjournal.markdown to 0.7.213
  • Fix #1882: support for reifying java.time.temporal.TemporalField (@EvenMoreIrrelevance)
  • Bump Selmer to 1.12.65
  • SCI: sci.impl.Reflector was rewritten into Clojure
  • dissoc on record with non-record field should return map instead of record
  • Bump edamame to 1.5.35
  • Bump core.rrb-vector to 0.2.0
  • Migrate detecting of executable name for self-executing uberjar executable from ProcessHandle to to native image ProcessInfo to avoid sandbox errors
  • Bump cli to 0.8.67
  • Bump fs to 0.5.29
  • Bump nextjournal.markdown to 0.7.201

• SCI: Configurable Clojure/Script interpreter suitable for scripting

  • Add support for :refer-global and :require-global
  • Add println-str
  • Fix #997: Var is mistaken for local when used under the same name in a let body
  • Fix #1001: JS interop with reserved js keyword fails (regression of #987)
  • sci.impl.Reflector was rewritten into Clojure
  • Fix babashka/babashka#1886: Return a map when dissociating a record basis field.
  • Fix #1011: reset ns metadata when evaluating ns form multiple times
  • Fix for https://github.com/babashka/babashka/issues/1899
  • Fix #1010: add js-in in CLJS
  • Add array-seq

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

  • #2600: NEW linter: unused-excluded-var to warn on unused vars in :refer-clojure :exclude (@jramosg)
  • #2459: NEW linter: :destructured-or-always-evaluates to warn on s-expressions in :or defaults in map destructuring (@jramosg)
  • Add type checking support for sorted-map-by, sorted-set, and sorted-set-by functions (@jramosg)
  • Add new type array and type checking support for the next functions: to-array, alength, aget, aset and aclone (@jramosg)
  • Fix #2695: false positive :unquote-not-syntax-quoted in leiningen's defproject
  • Leiningen's defproject behavior can now be configured using leiningen.core.project/defproject
  • Fix #2699: fix false positive unresolved string var with extend-type on CLJS
  • Rename :refer-clojure-exclude-unresolved-var linter to unresolved-excluded-var for consistency
  • v2025.12.23
  • #2654: NEW linter: redundant-let-binding, defaults to :off (@tomdl89)
  • #2653: NEW linter: :unquote-not-syntax-quoted to warn on ~ and ~@ usage outside syntax-quote (`) (@jramosg)
  • #2613: NEW linter: :refer-clojure-exclude-unresolved-var to warn on non-existing vars in :refer-clojure :exclude (@jramosg)
  • #2668: Lint & syntax errors in let bindings and lint for trailing & (@tomdl89)
  • #2590: duplicate-key-in-assoc changed to duplicate-key-args, and now lints dissoc, assoc! and dissoc! too (@tomdl89)
  • #2651: resume linting after paren mismatches
  • clojure-lsp#2651: Fix inner class name for java-class-definitions.
  • clojure-lsp#2651: Include inner class java-class-definition analysis.
  • Bump babashka/fs
  • #2532: Disable :duplicate-require in require + :reload / :reload-all
  • #2432: Don't warn for :redundant-fn-wrapper in case of inlined function
  • #2599: detect invalid arity for invoking collection as higher order function
  • #2661: Fix false positive :unexpected-recur when recur is used inside clojure.core.match/match (@jramosg)
  • #2617: Add types for repeatedly (@jramosg)
  • Add :ratio type support for numerator and denominator functions (@jramosg)
  • #2676: Report unresolved namespace for namespaced maps with unknown aliases (@jramosg)
  • #2683: data argument of ex-info may be nil since clojure 1.12
  • Bump built-in ClojureScript analysis info
  • Fix #2687: support new :refer-global and :require-global ns options in CLJS
  • Fix #2554: support inline configs in .cljc files

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

  • Minor: leave out :edamame/read-cond-splicing when not splicing
  • Allow :read-cond function to override :edamame/read-cond-splicing value
  • The result from :read-cond with a function should be spliced. This behavior differs from :read-cond + :preserve which always returns a reader conditional object which cannot be spliced.
  • Support function for :features option to just select the first feature that occurs

• squint: CLJS syntax to JS compiler

  • Allow macro namespaces to load "node:fs", etc. to read config files for conditional compilation
  • Don't emit IIFE for top-level let so you can write let over defn to capture values.
  • Fix js-yield and js-yield* in expression position
  • Implement some? as macro
  • Fix #758: volatile!, vswap!, vreset!
  • pr-str, prn etc now print EDN (with the idea that you can paste it back into your program)
  • new #js/Map reader that reads a JavaScript Map from a Clojure map (maps are printed like this with pr-str too)
  • Support passing keyword to mapv
  • #759: doseq can't be used in expression context
  • Fix #753: optimize output of dotimes
  • alength as macro

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

  • Performance enhancements
  • treat innerHTML as a property rather than an attribute
  • Drop support for camelCased properties / (css) attributes
  • Fix :default-value in input range
  • Support data param in :on-render
  • Support default values for uncontrolled components
  • Fix child count mismatch
  • Fix re-rendering/patching of subroots
  • Add :on-render hook for mounting/updating/unmounting third part JS components

• NEW: parmezan: fixes unbalanced or unexpected parens or other delimiters in Clojure files

• CLI: Turn Clojure functions into CLIs!

  • #126: - value accidentally parsed as option, e.g. --file -
  • #124: Specifying exec fn that starts with hyphen is treated as option
  • Drop Clojure 1.9 support. Minimum Clojure version is now 1.10.3.

• clerk: Moldable Live Programming for Clojure

  • always analyze doc (but not deps) when no-cache is set (#786)
  • add option to disable inline formulas in markdown (#780)

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

  • #114: Enable source maps (@jeroenvandijk)
  • #140: Enable customizing the nrepl websocket port (@PEZ)
  • Bump shadow-cljs and SCI

• Nextjournal Markdown

  • Add config option to avoid TeX formulas
  • API improvements for passing options

• cherry: Experimental ClojureScript to ES6 module compiler

  • Fix cherry compile CLI command not receiving file arguments
  • Bump shadow-cljs to 3.3.4
  • Fix #163: Add assert to macros (@willcohen)
  • Fix #165: Fix ClojureScript protocol dispatch functions (@willcohen)
  • Fix #167: Protocol dispatch functions inside IIFEs; bump squint accordingly
  • Fix #169: fix extend-type on Object
  • Fix #171: Add satisfies? macro (@willcohen)

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

  • Released several versions catching up with the clojure CLI

• quickdoc: Quick and minimal API doc generation for Clojure

  • Fix extra newline in codeblock

• quickblog: light-weight static blog engine for Clojure and babashka

  • Add support for a blog contained within another website; see Serving an alternate content root in README. (@jmglov)
  • Upgrade babashka/http-server to 0.1.14
  • Fix :blog-image-alt option being ignored when using CLI (bb quickblog render)

• nbb: Scripting in Clojure on Node.js using SCI

  • #395: fix vim-fireplace infinite loop on nREPL session close.
  • Add ILookup and Cons
  • Add abs
  • nREPL: support "completions" op

• neil: A CLI to add common aliases and features to deps.edn-based projects.
  

  • neil.el - a hook that runs after finding a package (@agzam)
  • neil.el - adds a function for injecting a found package into current CIDER session (@agzam)
  • #245: neil.el - neil-executable-path now can be set to clj -M:neil
  • #251: Upgrade library deps-new to 0.10.3
  • #255: update maven search URL

• fs - File system utility library for Clojure

  • #154 reflect in directory check and docs that move never follows symbolic links (@lread)
  • #181 delete-tree now deletes broken symbolic link root (@lread)
  • #193 create-dirs now recognizes sym-linked dirs on JDK 11 (@lread)
  • #184: new check in copy-tree for copying to self too rigid
  • #165: zip now excludes zip-file from zip-file (@lread)
  • #167: add root fn which exposes Path getRoot (@lread)
  • #166: copy-tree now fails fast on attempt to copy parent to child (@lread)
  • #152: an empty-string path "" is now (typically) understood to be the current working directory (as per underlying JDK file APIs) (@lread)
  • #155: fs/with-temp-dir clj-kondo linting refinements (@lread)
  • #162: unixify no longer expands into absolute path on Windows (potentially BREAKING)
  • Add return type hint to read-all-bytes

• process: Clojure library for shelling out / spawning sub-processes

  • #181: support :discard or ProcessBuilder$Redirect as :out and :err options

Contributions to third party projects:

• ClojureScript
  • CLJS-3466: support qualified method in return position
  • CLJS-3468: :refer-global should not make unrenamed object available

Other projects

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