CIDER’s code completion has quietly gotten quite good over the years, and I don’t think it gets enough credit. It’s all built on Emacs’s standard completion-at-point, so it works with whatever completion UI you prefer - the built-in one, Corfu, company - without any special setup. Under the hood compliment does the heavy lifting for Clojure (and clj-suitable for ClojureScript), which means smart, backend-driven matching: mai completes to map-indexed, cji to clojure.java.io, and an unimported BiFun to java.util.function.BiFunction. The candidates come back ranked by the backend and are context-aware - it knows when you’re inside a -> or completing a deftype field. Lately I’ve been giving the Emacs side of things some attention, to bring it in line with the modern completion stack so many of us now use - Vertico, Corfu, Consult, Marginalia and friends. Two changes are worth calling out. The first is about the symbol prompts. A number of CIDER commands ask you for a Clojure symbol when there’s nothing at point - cider-doc, cider-find-var and the like. Historically those prompts used the older completion machinery, so your completing-read UI didn’t kick in and you were left with TAB and a *Completions* buffer. There’s now cider-use-completing-read-for-symbol (off by default for now); turn it on and those prompts go through completing-read over a collection that queries the running REPL lazily as you type. Vertico, Ivy, Helm - whatever you drive completing-read with - just works, and the candidates carry their type and namespace. The second is smaller, but I like it a lot: annotations now line up in a proper column instead of trailing raggedly after each candidate. This comes from an affixation-function, the richer successor to the old annotation-function, so every frontend that understands it - the built-in *Completions*, Corfu, Vertico - renders the aligned version. company keeps showing its own trailing annotations, same as before. Both changes are in the latest CIDER MELPA build and will ship in the next stable release. As always, I’d love to hear how they work out for you. That’s all I have for you today. Keep hacking! P.S. If you use Embark, I wrote up a fun way to act on Clojure symbols with it - documentation, jump-to-definition, inspect and so on - over on Emacs Redux.

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Meta Redux

CIDER's code completion in Emacs has received two notable improvements. First, a new option `cider-use-completing-read-for-symbol` routes symbol prompts through `completing-read`, enabling modern completion UIs like Vertico, Ivy, and Helm to work with REPL-backed candidates that include type and namespace metadata. Second, completion annotations now align in a proper column via `affixation-function`, improving readability across supported frontends like Corfu and Vertico. Both changes are available in the latest CIDER MELPA build and will ship in the next stable release.

Modernizing CIDER's Completion