When writing documentation or blog posts about Clojure code, it is
very useful to be able to format Clojure code blocks using
clojure-mode
and evaluate code with nrepl.el
.
This can be enabled using mmm-mode
, which
allows a single buffer to use different major modes for different
sections of the buffer (and is not limited to just web modes).
Install mmm-mode
using M-x package-install mmm-mode
,
or using M-x el-get-install mmm-mode
from the excellent
el-get
, or by checking the project from github and
installing manually.
To configure this for clojure and markdown, add this in your init.el
or .emacs
file.
(require 'mmm-auto)
(mmm-add-classes
'((markdown-clojure
:submode clojure-mode
:face mmm-declaration-submode-face
:front "^```clj[\n\r]+"
:back "^```$")))
(setq mmm-global-mode 'maybe)
(mmm-add-mode-ext-class 'markdown-mode nil 'markdown-clojure)
After evaluating the above, or restarting emacs, you can test multi-mode support by opening a markdown document, or creating a new one, and adding a clojure source block, e.g.:
```clj (defn my-fn [x] (inc x)) (my-fn 1) ```
Inside the code block you can format and evaluate your code as in any
clojure-mode
buffer, and the code will display exactly as in a
.clj
file. By default the evaluation uses a running inferior lisp
process, which you must start yourself. To use a running
nrepl session instead, use M-x nrepl-interaction-mode
inside the code block.
This technique is not limited to clojure and markdown, but could be
made to work whenever you would like differing major modes in distinct
parts of your Emacs buffers. You can add class to mmm-mode
appropriately, for as many major mode combinations as you need. The
regions for each major mode are detected using regular expressions (or
by some function).
For example, if you’re writing asciidoc, you might use:
(mmm-add-classes
'((asciidoc-clojure
:submode clojure
:face mmm-declaration-submode-face
:front "\\[source, clojure\\][\n\r]+----[\n\r]+"
:back "^----$")))
(mmm-add-mode-ext-class 'adoc-mode nil 'asciidoc-clojure)
(mmm-add-mode-ext-class 'doc-mode nil 'asciidoc-clojure)
mmm-mode
allows you to flexibly use multiple major modes in
different parts of a single emacs buffer. Here we have shown how to
use it for clojure-mode
code blocks in markdown or asciidoc, but it
is in no way limited to this, and it allows some fine grained
customisation to the appearance and behaviour of each major mode
block. I’m sure you’ll find your own uses for mmm-mode
.