REPL-y

A fitter, happier, more productive REPL for Clojure.

Improvements over the existing REPL that comes in clojure.jar

• A number of readline commands, some not available in earlier JLine versions:
  • navigation to the start/end of lines, and forward/back by word
  • history navigation and search
  • and much much more
• CTRL-C:
  • kills the currently running command, breaks out of infinite loops, etc.
  • doesn't bail out of the process - stops interruption-friendly operations
• Code completion for:
  • Clojure vars and namespaces
  • Clojure namespace-qualified vars
  • Java classes, packages
  • Java package-qualified classes, static methods
• Optional nREPL integration

Installation

REPLy is bundled with Leiningen. If you're using it then you're covered.

Here's how to get a standalone version up and running (assuming you have Leiningen installed):

git clone https://github.com/trptcolin/reply.git
cd reply
lein compile
lein run

Usage

Leiningen

The easiest way to use REPLy is simply to run lein repl. That's it!

If you want to check out the latest stuff on REPLy main, you can run lein trampoline run in this project.

Clojure CLI (tools.deps)

Starting REPLy using the clojure command is as easy as:

clojure -Sdeps '{:deps {reply/reply {:mvn/version "0.6.0"}}}' -M -m reply.main

Note: REPLy doesn't pin a Clojure version - it's just a library, so the Clojure version comes from your own deps. To see what your setup resolves to, run clojure -e '(clojure-version)'. More on the distinction between the Clojure CLI and Clojure itself.

Other

If you want to use REPLy from another piece of software, your entry point should be reply.main/launch-nrepl. There are lots of options, which you can learn more about by running (println (last (reply.main/parse-args ["-h"]))).

Debugging

If you're having problems, feel free to open an issue, but the following may help.

For keybinding issues, check out ~/.inputrc - you can mostly use the same specifications there as you can with normal readline applications like bash, but from time to time we do come across missing features that we then add to jline.

By default REPLy quiets JLine's own logging: during startup it sets the org.jline java.util.logging logger to SEVERE. If you need to see what JLine is doing under the hood (handy for debugging keybinding issues), lower that logger's level to something more verbose like FINE after REPLy starts.

You can use the --standalone flag to rule out any nREPL-related questions, but I'm not aware of anyone using --standalone for other purposes. Please let me know if you are!

Thanks

Thanks to the developers of Clojure, JLine, nREPL, and incomplete for their work on the excellent projects that this project depends upon.

Special thanks to 8th Light for allowing me to work on this during our open-source Friday afternoons.

License

Copyright (C) 2011-2026 Colin Jones

Distributed under the Eclipse Public License, the same as Clojure. See the LICENSE file for details.