···
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<chapter xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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xml:id="module-services-emacs">
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Documentation contributors:
+
Damien Cassou @DamienCassou
+
<link xlink:href="http://www.gnu.org/software/emacs/">Emacs</link>
+
is an extensible, customizable, self-documenting real-time display
+
editor — and more. At its core is an interpreter for Emacs Lisp, a
+
dialect of the Lisp programming language with extensions to
+
Emacs runs within a graphical desktop environment using the X
+
Window System, but works equally well on a text terminal. Under
+
<productname>OS X</productname>, a "Mac port" edition is
+
available, which uses Apple's native GUI frameworks.
+
<productname>Nixpkgs</productname> provides a superior environment
+
for running <application>Emacs</application>. It's simple to
+
create custom builds by overriding the default packages. Chaotic
+
collections of Emacs Lisp code and extensions can be brought under
+
control using declarative package
+
management. <productname>NixOS</productname> even provides a
+
<command>systemd</command> user service for automatically
+
starting the Emacs daemon.
+
<title>Installing <application>Emacs</application></title>
+
Emacs can installed in the normal way for Nix (see <xref
+
linkend="sec-package-management" />). In addition, a NixOS
+
<emphasis>service</emphasis> can be enabled.
+
<title>The Different Releases of Emacs</title>
+
<productname>Nixpkgs</productname> defines several basic Emacs
+
packages. The following are attributes belonging to the
+
<varname>pkgs</varname> set:
+
<term><varname>emacs</varname></term>
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<term><varname>emacs24</varname></term>
+
The latest stable version of Emacs 24 using the <link
+
xlink:href="http://www.gtk.org">GTK+ 2</link> widget
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<term><varname>emacs24-nox</varname></term>
+
Emacs 24 built without any dependency on X11
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<term><varname>emacs24Macport</varname></term>
+
Emacs 24 with the "Mac port" patches, providing a more
+
native look and feel under OS X.
+
<term><varname>emacs25pre</varname></term>
+
A pretest version of what will become the first
+
If those aren't suitable, then the following imitation Emacs
+
editors are also available in Nixpkgs:
+
<link xlink:href="https://www.gnu.org/software/zile/">Zile</link>,
+
<link xlink:href="http://homepage.boetes.org/software/mg/">mg</link>,
+
<link xlink:href="http://yi-editor.github.io/">Yi</link>.
+
<title>Adding Packages to Emacs</title>
+
Emacs includes an entire ecosystem of functionality beyond
+
text editing, including a project planner, mail and news
+
reader, debugger interface, calendar, and more.
+
Most extensions are gotten with the Emacs packaging system
+
(<filename>package.el</filename>) from <link
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xlink:href="https://elpa.gnu.org/">Emacs Lisp Package Archive
+
(<acronym>ELPA</acronym>)</link>,
+
<link xlink:href="https://melpa.org/"><acronym>MELPA</acronym></link>,
+
<link xlink:href="https://stable.melpa.org/">MELPA Stable</link>,
+
and <link xlink:href="http://orgmode.org/elpa.html">Org ELPA</link>.
+
Nixpkgs is regularly updated to mirror all these archives.
+
Under NixOS, you can continue to use
+
<function>package-list-packages</function> and
+
<function>package-install</function> to install packages. You
+
can also declare the set of Emacs packages you need using the
+
derivations from Nixpkgs. The rest of this section discusses
+
declarative installation of Emacs packages through nixpkgs.
+
This documentation describes the new Emacs packages
+
framework in NixOS 16.03
+
(<varname>emacsPackagesNg</varname>) which should not be
+
confused with the previous and deprecated framework
+
(<varname>emacs24Packages</varname>).
+
The first step to declare the list of packages you want in
+
your Emacs installation is to create a dedicated
+
derivation. This can be done in a dedicated
+
<filename>emacs.nix</filename> file such as:
+
<example xml:id="ex-emacsNix">
+
<title>Nix expression to build Emacs with packages (<filename>emacs.nix</filename>)</title>
+
<programlisting language="nix">
+
This is a nix expression to build Emacs and some Emacs packages I like
+
from source on any distribution where Nix is installed. This will install
+
all the dependencies from the nixpkgs repository and build the binary files
+
without interfering with the host distribution.
+
To build the project, type the following from the current directory:
+
To run the newly compiled executable:
+
{ pkgs ? import <nixpkgs> {} }: <co xml:id="ex-emacsNix-1" />
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myEmacs = pkgs.emacs; <co xml:id="ex-emacsNix-2" />
+
emacsWithPackages = (pkgs.emacsPackagesNgGen myEmacs).emacsWithPackages; <co xml:id="ex-emacsNix-3" />
+
emacsWithPackages (epkgs: (with epkgs.melpaStablePackages; [ <co xml:id="ex-emacsNix-4" />
+
magit # ; Integrate git <C-x g>
+
zerodark-theme # ; Nicolas' theme
+
]) ++ (with epkgs.melpaPackages; [ <co xml:id="ex-emacsNix-5" />
+
undo-tree # ; <C-x u> to show the undo tree
+
zoom-frm # ; increase/decrease font size for all buffers %lt;C-x C-+>
+
]) ++ (with epkgs.elpaPackages; [ <co xml:id="ex-emacsNix-6" />
+
beacon # ; highlight my cursor when scrolling
+
nameless # ; hide current package name everywhere in elisp code
+
pkgs.notmuch # From main packages set <co xml:id="ex-emacsNix-7" />
+
<callout arearefs="ex-emacsNix-1">
+
The first non-comment line in this file
+
(<literal>{ pkgs ? ... }</literal>)
+
indicates that the whole file represents a function.
+
<callout arearefs="ex-emacsNix-2">
+
The <varname>let</varname> expression below defines a
+
<varname>myEmacs</varname> binding pointing to the current
+
stable version of Emacs. This binding is here to separate the
+
choice of the Emacs binary from the specification of the
+
<callout arearefs="ex-emacsNix-3">
+
This generates an <varname>emacsWithPackages</varname>
+
function. It takes a single argument: a function from a
+
package set to a list of packages (the packages that will
+
be available in Emacs).
+
<callout arearefs="ex-emacsNix-4">
+
The rest of the file specifies the list of packages to
+
install. In the example, two packages
+
(<varname>magit</varname> and
+
<varname>zerodark-theme</varname>) are taken from MELPA
+
<callout arearefs="ex-emacsNix-5">
+
Two packages (<varname>undo-tree</varname> and
+
<varname>zoom-frm</varname>) are taken from MELPA.
+
<callout arearefs="ex-emacsNix-6">
+
<para>Three packages are taken from GNU ELPA.</para>
+
<callout arearefs="ex-emacsNix-7">
+
<varname>notmuch</varname> is taken from a nixpkgs derivation
+
which contains an Emacs mode.
+
The result of this configuration will be an
+
<command>emacs</command> command which launches Emacs with all
+
of your chosen packages in the <varname>load-path</varname>.
+
You can check that it works by executing this in a terminal:
+
$ ./result/bin/emacs -q
+
and then typing <literal>M-x package-initialize</literal>.
+
Check that you can use all the packages you want in this
+
Emacs instance. For example, try switching to the zerodark
+
<literal>M-x load-theme <RET> zerodark <RET> y</literal>.
+
A few popular extensions worth checking out are: auctex,
+
company, edit-server, flycheck, helm, iedit, magit,
+
multiple-cursors, projectile, and yasnippet.
+
The list of available packages in the various ELPA
+
repositories can be seen with the following commands:
+
<title>Querying Emacs packages</title>
+
<programlisting><
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