Clojure layer

• REPL via CIDER
• Code formatting via CIDER using Cljfmt
• Refactoring via clj-refactor
• Aligning of code forms via clojure-mode
• Debugging with sayid
• Advanced help with helm-cider
• Structuraly safe editing using optional evil-cleverparens
• Linting via clj-kondo (joker and squiggly-clojure also available)

Edit the ~/.spacemacs file and add the word clojure to the existing dotspacemacs-configuration-layers list.

Pretty symbols for anonymous functions, set literals and partial, like (λ [a] (+ a 5)), ƒ(+ % 5), ∈{2 4 6} and Ƥ.

To enable this feature, add the following snippet to the dotspacemacs/user-config section of your ~/.spacemacs file:

(setq clojure-enable-fancify-symbols t)

Or set this variable when loading the configuration layer:

(setq-default dotspacemacs-configuration-layers
'((clojure :variables clojure-enable-fancify-symbols t)))

Traditionally the clojure developing environment is working exclusively with an external server called CIDER. This has some drawbacks especially that most features require a working REPL session in the background. Newer layers work with a standard LSP server providing standard bindings for most features. In addition lsp-UI provides a more modern UI for visualising linter results and providing code actions.

The server is automatically activated when you have the lsp-layer installed in your dotfile. Alternatively you can force a certain backend by setting the clojure-backend variable in your dotfile:

(setq-default dotspacemacs-configuration-layers
'((clojure :variables clojure-backend 'lsp)))

The server is started automatically when a supported file is opened. It will also provide a flycheck integration via lsp-flycheck which will run the configured linter from your project config. See here for details. The server is installed automatically in your emacs directory however if this does not work it can also be installed manually from here.

You can also explicitly disable lsp support by setting cider as backend explicitly:

(setq-default dotspacemacs-configuration-layers
'((clojure :variables clojure-backend 'cider)))

clj-kondo, joker and squiggly-clojure provide automated linting via flycheck. These packages are disabled by default as they require the relevant linter binaries to be installed locally.

The recommended linter is to use clj-kondo in combination with joker. Together they catch the most issues while both running extremely quickly.

squiggly reloads your code on every change which gives unexpected results if your code is not re-loadable. squiggly also requires org.clojure/core.typed be added to the development dependencies of your projects or build tool when using cider-connect.

Run unit tests with Kaocha via CIDER.

Enable the Kaocha feature via setting the clojure-enable-kaocha-runner variable in your dotfile:

(setq-default dotspacemacs-configuration-layers
'((clojure :variables clojure-enable-kaocha-runner t)))

The kaocha library must be included when starting a REPL, either through Leiningen dev profile dependency

:profiles {:dev {:dependencies [[lambdaisland/kaocha "1.60.977"]]}}

or a Clojure CLI alias in a project deps.edn or user wide deps.edn file

:lib/kaocha {:extra-deps {lambdaisland/kaocha {:mvn/version "1.60.977"}}}

practicalli/clojure-deps-edn contains an example :lib/kaocha alias

Open a Clojure file (.clj, .cljs, .cljc, .edn) and start a Clojure REPL, choosing the REPL session type (Clojure, ClojureScript or both Clojure & ClojureScript).

, ' and , s i calls the sesman-start command, a wrapper for all the jack-in and connect commands. A prompt appears allowing you to choose the type of REPL session required.

, s j opens the cider-jack-in menu, providing commands to start specific REPL sessions, it is the same as using the sesman-start command described previously.

Using the universal constant, SPC u before any of the previous commands enables editing of the command that starts the REPL. This is useful if you want to add a deps.edn alias or add your own dependencies to inject. The command is edited in the mini-buffer

Once the REPL starts, a confirmation message is displayed in the mini-buffer.

The REPL buffer does not open automatically (Clojure is typically evaluated in the source code buffer). , s a will switch between REPL and source code buffers, opening the REPL buffer if not already shown.

Start a REPL outside of Emacs that includes an nREPL server. The IP address and port the nREPL runs on should be printed.

, '_ or SPC m s i displays the sesman prompt, select the connect command relevant to the type of REPL you wish to start.

, s c opens the cider-connect menu, providing key bindings for connecting too the different REPL session types.

CIDER communicates with your Clojure process through nREPL and for CIDER to function correctly extra nREPL middleware is needed (cider/cider-nrepl). The same is true for clj-refactor (refactor-nrepl), and for sayid (com.billpiel/sayid).

When starting the Clojure process through cider (cider-jack-in and friends) this will be handled automatically, and so most users should be able to just run SPC m s i to connect to the CIDER REPL and skip the rest of this section.

If you are running an older version of CIDER (0.10 or older), or if you are starting the Clojure process yourself outside of Emacs, then you need to make sure the necessary dependencies are present, and the necessary nREPL middlewares are enabled.

Sesman is used for managing REPL connections when working simultaneously on multiple projects or have multiple connections opened for the same project

SPC m m i provides information about the current REPL. SPC m m b shows information about all REPLs currently active. SPC m m l menu links files, directories and projects to an existing session.

See REPL connections in the key bindings section for all the commands.

This layer installs the helm-cider package which provides helm integration with cider apropos. It also embeds cider cheatsheet.

Type SPC m h a to display advanced apropos window. Type SPC m h c to display the cheatsheet then type in some terms (space separated) to narrow down the list. For example, try typing in "sort map" to see some functions that deal with sorting maps.

NOTE: If helm is not used, then cider-apropos and cider-cheatsheet are used.

The Clojure layer adds support for evil-cleverparens which allows to safely edit lisp code by keeping the s-expressions balanced.

SPC m T s will toggle safe structured editing, off by default.

Enable safe structural editing for all clojure buffers using the following in the dotspacemacs/user-config function of your .spacemacs file

(spacemacs/toggle-evil-safe-lisp-structural-editing-on-register-hook-clojure-mode)

Or enable safe structural editing for all supported modes:

(spacemacs/toggle-evil-safe-lisp-structural-editing-on-register-hooks)

When enabled the symbol 🆂 will display in the mode-line.

Spacemacs comes with a special lisp-state for working with lisp code that supports slurpage, barfage and more tools you'll likely want when working with lisp.

As this state works the same for all files, the documentation is in global DOCUMENTATION.org. In general, use SPC k to interact with the lisp-state.

In general, q should always quit the popped up buffer.

With a Indentation spec functionality of Cider to read the custom indentation rules from the var's metadata, it is better for consistency reasons to not add the custom indentation rules to Spacemacs, but to add them to the metadata of those specific vars.