Basic interaction with a Clojure subprocess
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License GPL 3 MELPA MELPA Stable


This package provides basic interaction with a Clojure subprocess (REPL). It's based on ideas from the popular inferior-lisp package.

inf-clojure has two components - a nice Clojure REPL with auto-completion and a minor mode (inf-clojure-minor-mode), which extends clojure-mode with commands to evaluate forms directly in the REPL.

inf-clojure provides a set of essential features for interactive Clojure(Script) development:

  • REPL
  • Interactive code evaluation
  • Code completion
  • Definition lookup
  • Documentation lookup
  • ElDoc
  • Apropos
  • Macroexpansion
  • Require :reload/:reload-all
  • Support connecting to socket REPLs
  • Support for Lumo
  • Support for Planck

For a more powerful/full-featured solution see CIDER.


Available on all major package.el community maintained repos - MELPA Stable and MELPA repos.

MELPA Stable is recommended as it has the latest stable version. MELPA has a development snapshot for users who don't mind breakage but don't want to run from a git checkout.

You can install inf-clojure using the following command:

M-x package-install [RET] inf-clojure [RET]

or if you'd rather keep it in your dotfiles:

(unless (package-installed-p 'inf-clojure)
  (package-install 'inf-clojure))

If the installation doesn't work try refreshing the package list:

M-x package-refresh-contents

Add the following to your Emacs config to enable inf-clojure-minor-mode for Clojure source buffers:

(add-hook 'clojure-mode-hook #'inf-clojure-minor-mode)

Don't enable inf-clojure-minor-mode and cider-mode at the same time. They have overlapping functionality and keybindings and the result will be nothing short of havoc.


Just invoke M-x inf-clojure or press C-c C-z within a Clojure source file. This will start a REPL process for the current project and you can start interacting with it.

Inf-clojure has several custom variables which control the command used to start a REPL for a particular project type:

Detection is attempted in the above order but the inf-clojure-project-type variable can force a particular project type, useful for projects that don't have standard layouts.

It is highly recommended to use a cons pair like ("localhost" . 5555) to connect to a socket REPL, terminal REPLs are inherently hard to work with and support will be deprecated in the foreseeable future.

Interactively, use M-x inf-clojure-connect (C-c M-c) to connect to a running socket REPL or C-u C-c C-z for specifying a different command/cons pair.

You can also set custom values to inf-clojure variables on a per-project basis using directory variables.

For a list of all available commands in inf-clojure-mode (a.k.a. the REPL) and inf-clojure-minor-mode you can either invoke C-h f RET inf-clojure-mode and C-h f RET inf-clojure-minor-mode or simply browse their menus.

Many inf-clojure-minor-mode commands by default act on the symbol at point. You can, however, change this behaviour by invoking such commands with a prefix argument. For instance: C-u C-c C-v will ask for the symbol you want to show the docstring for.

Clojure Command Line Socket REPL

If you have the new Clojure CLI tools installed you can use the clojure command:

do not use clj because it adds readline support

clojure -J-Dclojure.server.repl="{:port 5555 :accept clojure.core.server/repl}"

Then either C-c M-c RET localhost RET 5555 from within Emacs or add the following to your .dir-locals.el:

((nil . ((inf-clojure-tools-deps-cmd . ("localhost" . 5555)))))

or the following to your Emacs init file:

(setf inf-clojure-tools-deps-cmd '("localhost" . 5555)):

Leiningen Socket REPL

For Leiningen, add the following option to your ~/.lein/profiles.clj or your project.clj:

:jvm-opts ["-Dclojure.server.repl={:port 5555 :accept clojure.core.server/repl}"]

Then run lein repl from within your project directory to start the REPL, and either C-c M-c RET localhost RET 5555 from within Emacs or add the following to your .dir-locals.el:

((nil . ((inf-clojure-lein-cmd . ("localhost" . 5555)))))

or the following to your Emacs init file:

(setf inf-clojure-lein-cmd '("localhost" . 5555))

Boot Socket REPL

For boot, export the environment variable BOOT_JVM_OPTIONS:

export BOOT_JVM_OPTIONS='-Dclojure.server.repl="{:port 5555 :accept clojure.core.server/repl}"'

or add the following to your .dir-locals.el:

((nil . ((inf-clojure-boot-cmd . ("localhost" . 5555)))))

or the following to your Emacs init file:

(setf inf-clojure-boot-cmd '("localhost" . 5555))

The socket server REPL configuration options are described here.

Lumo Socket REPL

Lumo is decoupled from inf-clojure-project-type and therefore the command used depends on what you are using for dependency resolution.

For example if a project.clj is present in the project root folder, inf-clojure-lein-cmd will be used.

After you launch lumo ... -n 5555, as customary, either C-c M-c RET localhost RET 5555 from within Emacs or add the following to your .dir-locals.el:

((nil . ((inf-clojure-lein-cmd . ("localhost" . 5555)))))

or the following to your Emacs init file:

(setf inf-clojure-lein-cmd '("localhost" . 5555))

Project detection can be completely skipped and the generic project type can be used instead:

(setf inf-clojure-project-type . "generic")
(setf inf-clojure-generic-cmd '("localhost" 5555))


Note that if you decide NOT to use the socket repl, it is highly recommended you disable output coloring and/or readline facilities: inf-clojure does not filter out ASCII escape characters at the moment and will not behave correctly.

You can disable coloring the following way for boot:

((nil . ((inf-clojure-boot-cmd . "boot repl -C"))))

For leiningen, there are no command line switches and you need to add a custom project.clj option:

  :repl-options {:color false}

Multiple Process Support

To run multiple Clojure processes, you start the first up with inf-clojure. It will be in a buffer named *inf-clojure*. Rename this buffer with rename-buffer. You may now start up a new process with another inf-clojure. It will be in a new buffer, named *inf-clojure*. You can switch between the different process buffers with switch-to-buffer.

Commands that send text from source buffers to Clojure processes (like inf-clojure-eval-defun or inf-clojure-show-arglists) have to choose a process to send to, when you have more than one Clojure process around. This is determined by the global variable inf-clojure-buffer.

Suppose you have three inferior Clojures running:

    Buffer              Process
    ------              -------
    foo                 inf-clojure
    bar                 inf-clojure<2>
    *inf-clojure*       inf-clojure<3>

If you do a inf-clojure-eval-defun command on some Clojure source code, what process do you send it to?

  • If you're in a process buffer (foo, bar, or inf-clojure), you send it to that process.
  • If you're in some other buffer (e.g., a source file), you send it to the process attached to buffer inf-clojure-buffer.

This process selection is performed by function inf-clojure-proc. Whenever inf-clojure fires up a new process, it resets inf-clojure-buffer to be the new process's buffer. If you only run one process, this does the right thing. If you run multiple processes, you might need to change inf-clojure-buffer to whichever process buffer you want to use.

Configuration options

In the time-honoured Emacs tradition inf-clojure's behaviour is extremely configurable.

You can see all the configuration options available using the command M-x customize-group RET inf-clojure.


An inf-clojure REPL can be of different types: Clojure, ClojureScript, Lumo and Planck are all potentially valid options.

At the moment, the default Clojure REPL, the Lumo REPL and the Planck REPL are supported (standard ClojureScript is lacking mostly because some features require to access the compiler state, cljs-tooling is a good candidate for enabling support).

What does it mean that a REPL type is supported - well it means that inf-clojure would use the proper code internally to power commands like definition lookup and friends. Those differ from REPL to REPL and can't be implemented in a REPL-independent way. At boot type inf-clojure tries to detect the type of the REPL that was started and uses this type to dispatch the proper code for the respective REPL type.

By default inf-clojure would start a standard Clojure REPL using lein or boot but you can easily change this. To boot some other REPL just use the right launch command (or connect to the REPL via a socket). For example, for Lumo just add the following in your .dir-locals.el:

((nil . ((inf-clojure-boot-cmd . "lumo -d")))) ;; inf-clojure-lein-cmd if you are using Leiningen


eldoc-mode is supported in Clojure source buffers and *inferior-clojure* buffers which are running a Clojure REPL.

When ElDoc is enabled and there is an active REPL, it will show the argument list of the function call you are currently editing in the echo area.

You can activate ElDoc with M-x eldoc-mode or by adding the following to you Emacs config:

(add-hook 'clojure-mode-hook #'eldoc-mode)
(add-hook 'inf-clojure-mode-hook #'eldoc-mode)

ElDoc currently doesn't work with ClojureScript buffers and REPL's. You can leave it enabled, it just won't show anything in the echo area.

Code Completion

Code completion is particularly open to customization. Not only you can setq the customary inf-clojure-completion-form, inf-clojure-completion-form-lumo and inf-clojure-completion-form-planck - the form to send to the REPL - but you can also use inf-clojure-completions-fn for specifying a function that given the REPL response should return elisp data compatible with completion-at-point-functions. For more info run M-x describe-variable RET inf-clojure-completions-fn. Another option is to have a look at how cider does it.

Lumo Setup

For an optimal Lumo experience the -d needs to be passed to Lumo when launched from the command line. This disable readline support in order to play nicely with emacs.

For example, you can use the following command (assuming cp contains the classpath) in your .dir-locals.el:

((nil . (eval . (setq inf-clojure-generic-cmd (concat "lumo -d -c "
                                                      (f-read (concat (inf-clojure-project-root) "cp")))))))


REPL not responsive in Windows OS

In Windows, the REPL is not returning anything. For example, type (+ 1 1) and press ENTER, the cursor just drops to a new line and nothing is shown.

The explanation of this problem and solution can be found here.

The solution is to create a file named .jline.rc in your $HOME directory and add this line to that file:


Log process activity

Standard Emacs debugging turns out to be difficult when an asynchronous process is involved. In this case try to enable logging:

(setq inf-clojure-log-activity t)

This creates .inf-clojure.log in the project directory so that you can tail -f on it.


Copyright © 2014-2018 Bozhidar Batsov and contributors.

Distributed under the GNU General Public License; type C-h C-c to view it.