Start an nREPL Server

One of the biggest selling points of Clojure as a language is interactive development. To partake in that you need what we call a "REPL." This lets you write code in one tab of your editor and test it out live in another.

Enough digital ink has been spilled on that subject that I am going to forgo a full guide on that process for the moment.

• Add an alias to your deps.edn for nREPL

  {...
   :aliases {:nREPL
              {:extra-deps
                {nrepl/nrepl {:mvn/version "1.3.0"}}}}}
             

  nREPL lets you connect to a running Clojure program "remotely." This can mean over the internet, but for local development it's just your machine.

• Add a recipe to your Justfile for running nREPL.

  Use clojure -M:nREPL -m nrepl.cmdline as the command. The -M:nREPL activates the alias and -m nrepl.cmdline launches the nREPL.

  help:
      just --list
  
  run:
      clojure -M -m main
  
  nrepl:
      clojure -M:nREPL -m nrepl.cmdline

• Connect to nREPL from your editor.

  The instructions for this vary based on your editor. For the Clojure VSCode plugin, the documentation is HERE. For IntelliJ it is HERE.

  Your editor likely also has a way to start its own nREPL server. Feel free to use that if you like. The important thing is that you are able to load code into a REPL as you are making your program.