clomacs

Emacs is a Lisp. Clojure is a Lisp. Can the two be put together to form the ultimate dev environment? "Clomacs" perhaps?

from Emacs isn't for everyone discussion by Anonymous Cow.

Clomacs simplifies call Clojure code from Emacs lisp and vice versa. The purpose is to provide a tool for creating mixed Elisp-Clojure Emacs extensions. It provides a small wrapper under CIDER to reduce repetitive code and uses simple-httpd to call Elisp from Clojure via http requests.

Overview

There are some requirements to run mixed Elisp-Clojure code. All the Elisp-side code should be loaded, nREPL must run with all related Clojure-side code and its dependencies.

So, the user of the mixed Elisp-Clojure Emacs extension wants to simple run Elisp code from the extension.

The purpose of the clomacs-defun is to wrap Clojure function in a Elisp function, that will start CIDER if necessary or use an existing CIDER connection of certain Elisp-Clojure Emacs extension, call this Clojure function and return it's result.

To run Elisp code from Clojure, http server on Emacs side should be started first by clomacs-httpd-start function. Then you can straightforwardly pass Elisp code as string to Emacs for eval - clomacs-eval or wrap Elisp to Clojure function via clomacs-defn.

Installation

Elisp side

Add MELPA (if not yet) to your package-archives list.

Then you can install clomacs with the following command:

M-x package-install [RET] clomacs [RET]

Clojure side

To install Clomacs, add the following dependency to your project.clj file:

Usage

Prerequisites

clomacs requires Clojure 1.7+.

Simple example

Call Clojure from Elisp:

;; emacs lisp:
(require 'clomacs)
(clomacs-defun get-property System/getProperty)
(message (get-property "java.version"))

Call Elisp from Clojure:

;; emacs lisp:
(require 'clomacs)
(clomacs-httpd-start)

;; clojure:
(use 'clomacs)
(clomacs-defn emacs-version emacs-version)
(println (emacs-version))

Here System/getProperty is a Clojure function and get-property is a wrapped Elisp function. emacs-version is Elisp function and after macros evaluation - is a wrapped Clojure function.

Full-fledged example

The full source code for the following example is here: cm-test.

1. Create new Clojure project in a common way:

lein new cm-test

2. Add markdown-clj dependency to the project.clj file, add src/clj folder to the classpath:

(defproject cm-test "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :source-paths ["src/clj"]                    ;; add clj folder to the classpath
  :dependencies [[org.clojure/clojure "1.9.0"] ;; Use recent version of Clojure
                 [markdown-clj "0.9.28"]       ;; markdown-clj dependency
                 [clomacs "0.0.3-SNAPSHOT"]])  ;; Most recent version of clomacs

3. Create clj folder in the src/.
4. Copy cm_test to src/clj/ folder.
5. Add some code, using markdown lib in the src/clj/cm_test/core.clj file:

(ns cm-test.core
  (:use markdown.core))

(defn my-md-to-html-string
  "Call some function from the dependency."
  [x]
  (md-to-html-string x))

6. Create elisp folder in the src/.
7. Create cm-test.el file in this foder.
8. Add to the cm-test.el the following content:

(require 'clomacs)
(clomacs-defun cm-test-md-to-html-wrapper
               cm-test.core/my-md-to-html-string
               :lib-name "cm-test"
               :namespace cm-test.core
               :doc "Convert markdown to html via Clojure lib.")

(defun cm-test-mdarkdown-to-html (beg end)
  "Add to the selected markdown text it's html representation."
  (interactive "r")
  (save-excursion
    (if (< (point) (mark))
        (exchange-point-and-mark))
    (insert
     (concat "\n" (cm-test-md-to-html-wrapper
                   (buffer-substring beg end))))))

(provide 'cm-test)

Here is the cm-test/src path tree vizualization:

src
- clj
  - cm_test
    - core.clj
- elisp
  - cm-test.el

9. So, it can be used in your .emacs via:

(add-to-list 'load-path "~/.emacs.d/cm-test/src/elisp/")
(require 'cm-test)

10. Then mark (select) this text in one of your buffers:
# This is a test
and run M-x cm-test-mdarkdown-to-html.

<h1>This is a test</h1> should occurs in the buffer under the original text.

Projects uses clomacs:

cm-test - Clomacs usage example.
ejc-sql - Emacs SQL client uses Clojure JDBC.
flower - Integration with Github, Gitlab, Atlassian Jira, Microsoft TFS, Microsoft Exchange and Slack.

Requirements:

License

Distributed under the General Public License, version 3.

clojure-emacs / clomacs

readme