Fix error with Cider Clojure REPL in Emacs on Guix

I am currently reading Clojure for the brave and true by Daniel Higginbotham and in Chapter 2 about how to use Emacs for Clojure, there are instructions on how to set up Emacs with Cider, a Clojure REPL. I tried installing the package with a use-package configuration with :ensure t and I got the package. However, when I tried using it as the book instructed, I just got an error. I then realised the need for OpenJDK and Clojure and installed those with my home-config.scm file in Guix. I tried again and I still got the same error. I then tried installing emacs-cider from Guix as well with the hope that maybe there was some kind of incompatibility between OpenJDK, Clojure and Cider that was ironed out in the guix package. It still did not work.

I tried looking up the error and found a blog post that suggested installing OpenJDK non-Guixily by downloading a binary and adding it to the $PATH which solved the problem for that user. I did not really want this, since I really like the idea of installing my whole system with a scheme file or two in a reproducible way. (I'm not there yet, but I hope to get there over time. I just started using Guix as my main distro a few weeks ago. For now, after installing Guix System or Guix on another distro, I do some manual work and then run a Shell script to set up a few folders and run the command that applies my home-config.)

Tonight, a day later, I DuckDuckWent again and found another blog post about Clojure that told me that since there are three outputs for the openjdk package, to get everything I would need for Clojure, I should install openjdk:jdk, not simply openjdk which would give me openjdk:out. In addition, I also added openjdk:doc since I am a fan of having as much documentation as possible available on my local machine. I saw a video where that documentation was read from inside Cider a couple of days ago, so I thought it might come in handy. Come to think of it, maybe that was accessed over the internet, not from the local machine. Anyway, it doesn't hurt to have some documentation.

And now, everything just works. Turns out the problem was just user error. Whenever there are multiple outputs of a package in Guix, it is important to know what you get with each output and choose accordingly. As someone who just recently switched my main machine to Guix, this is very useful information that I had not seen before. I thought I would write this up in a blog post so people out there trying to fix the same problem have a chance of finding a solution faster than I did, and for my own future reference.