When I wrote about nREPL 0.7 last week I mentioned that some really exciting things were happening in the broader nREPL/Clojure community and today I want to expand a bit on those. The general theme today is that nREPL is getting more mindshare and broader tool support. The subtheme is that many tools can end up being able to support more programming languages due to nREPL’s language-agnostic nature.

The format I’ve adopted for this post is a bit chaotic and unstructured, but I hope you’ll forgive me. So, here we go.

iced-vim Adds support for nREPL’s Sideloader

We didn’t have to wait long for some editor to adopt the new sideloading functionality in nREPL 0.7 - iced-vim 1.3 did this only a couple of days after nREPL was released.

You can check out iced-vim’s sideloader documentation for more details.

So, which client will be next?

Chlorine Adds Alpha Support for nREPL

After the demise of Proto REPL, Chlorine has been the undisputed Clojure ruler of the realm of Atom. Chlorine has historically relied on unrepl to power its functionality, but the recently released version 0.5 added alpha support for nREPL!

Chlorine’s author, Mauricio Szabo, wrote a couple of cool blog posts on the topic that I can heartily recommend:

I’m pretty sure Chlorine’s support for nREPL will improve a lot in the months to come.

Conjure Adds Support for nREPL

In other (amazing) news - Oliver Caldwell has been working on a rewrite of Conjure, that’s powered by nREPL and may (will?) support other programming languages besides Clojure!

The project is off to a very promising start and I’m very excited about it!

Calva’s new Debugger

Calva, CIDER’s dear sibling, now has an interactive debugger! It utilizes cider-nrepl and VS Code’s debugger extension API. This work has been done as part of the Clojurists Together Q1 2020 funding period.

I’m super excited to finally see another editor reusing CIDER’s debugger, and I’m looking forward to seeing which editor will be next!

Babashka Now Ships with a Native nREPL Server

These days everyone has been raging about the awesome babashka, that increased the reach of Clojure almost as much as ClojureScript did a few years ago. Scripting in Clojure is a dream come true for so many people!

The industrious Michiel Borkent (a.k.a. borkdude) recently unveiled native nREPL support for babashka in version 0.0.79. What’s more - he did such a great job that the new server works pretty well with CIDER and you’ll even get code completion! Michiel shared with me earlier today a short presentation he did for the Amsterdam Clojure User Group on the subject.

Somewhat amusingly, all of this was achieved with 231 lines of code. I think that’s a great testament to the simplicity of nREPL.

Arcadia’s nREPL Server is a New Hope for ClojureCLR

Early on nREPL was ported to ClojureCLR. That port, named nREPL CLR, was a 1:1 reimplementation of the Clojure version, and was off to a pretty strong start. Unfortunately, this port was abandoned relatively quickly, and probably doesn’t even work these days. The lack of an nREPL server for ClojureCLR meant that its users could not take advantage of many of the most popular editor plugins and IDEs for Clojure, but this is finally changing.

Arcadia’s team have implemented a pretty solid nREPL server for the CLR. I’m hoping that as it matures it will lead to a much improved access to top-notch Clojure dev tooling for ClojureCLR. I’m hoping that the server will be extracted from Arcadia’s codebase soon and will be distributed as a standalone project for the benefit of the entire ClojureCLR community.

Even though the server is written in C#, its entire code is something like 500 lines of code. If you’re into ClojureCLR I’d encourage you to check out the project and try to help.

nREPL for ClojureScript

I guess most people know that nREPL has supported ClojureScript for ages via Piggieback. Piggieback is a pretty cool solution, but it comes with a few quirks and with one important limitation - it doesn’t work with self-hosted ClojureScript, as it’s written in Clojure. This means that if you’re into Lumo and Planck you can’t use with them with your favourite nREPL client. This, however, might change soon as well…

Chris Badahdah has been working for a while on a native nREPL implementation in ClojureScript, which won’t have this limitation. If you’re into ClojureScript, I’d encourage you to help him with the project.


Let’s wrap things up with several smaller news:

As usual - I welcome help with everything nREPL-related! Don’t be shy, we’ve got fun, challenging and rewarding tasks for everyone!


What a wild ride! I don’t know about you, but so much new things happening in nREPL’s world feels like Christmas to me! I think it’s reasonably safe to say that nREPL’s community is bursting with energy and ideas these days and I’m very optimistic about the future. We’ve achieved a lot already, but I feel the best is yet to come…

Keep hacking! May the (n)REPL be with you always!