@node Emacs Interface
@section Emacs Interface

@cindex Emacs
GNU Guix comes with a visual user interface for GNU@tie{}Emacs, known
as ``guix.el''.  It can be used for routine package management tasks,
pretty much like the @command{guix package} command (@pxref{Invoking
guix package}).  Specifically, ``guix.el'' makes it easy to:

@itemize
@item browse and display packages and generations;
@item search, install, upgrade and remove packages;
@item display packages from previous generations;
@item do some other useful things.
@end itemize

@menu
* Initial Setup: Emacs Initial Setup.	Preparing @file{~/.emacs}.
* Usage: Emacs Usage.			Using the interface.
* Configuration: Emacs Configuration.	Configuring the interface.
* Pretty SHA Path: Emacs Pretty Path.	Prettifying @file{/gnu/store/@dots{}} paths.
@end menu

@node Emacs Initial Setup
@subsection Initial Setup

To be able to use ``guix.el'', you need to install the following
packages:

@itemize
@item
@uref{http://www.gnu.org/software/emacs/, GNU Emacs}, version 24.3 or
later;

@item
@uref{http://nongnu.org/geiser/, Geiser}, version 0.3 or later: it is
used for interacting with the Guile process.

@end itemize

When it is done, add the following into your init file (@pxref{Init
File,,, emacs, The GNU Emacs Manual}):

@example
(require 'guix-init nil t)
@end example

However there is a chance that @code{load-path} of your Emacs does not
contain a directory with ``guix.el'' (usually it is
@file{/usr/share/emacs/site-lisp/}).  In that case you need to add it
before requiring (@pxref{Lisp Libraries,,, emacs, The GNU Emacs
Manual}):

@example
(add-to-list 'load-path "/path/to/directory-with-guix.el")
(require 'guix-init)
@end example

Do not worry about the efficiency of that @code{require} thing.  It will
not load the whole ``guix.el'' package, it will just autoload the main
interactive commands (@pxref{Autoload,,, elisp, The GNU Emacs Lisp
Reference Manual}).


@node Emacs Usage
@subsection Usage

Once ``guix.el'' has been successfully configured, you should be able to
use commands for displaying packages and generations.  This information
can be displayed in a ``list'' or ``info'' buffer.

@menu
* Commands: Emacs Commands.			@kbd{M-x guix-@dots{}}
* General information: Emacs General info.	Common for both interfaces.
* ``List'' buffer: Emacs List buffer.		List-like interface.
* ``Info'' buffer: Emacs Info buffer.		Help-like interface.
@end menu

@node Emacs Commands
@subsubsection Commands

All commands for displaying packages and generations use the current
profile, which can be changed with
@kbd{M-x@tie{}guix-set-current-profile}.  Alternatively, if you call any
of these commands with prefix argument (@kbd{C-u}), you will be prompted
for a profile just for that command.

Commands for displaying packages:

@table @kbd

@item M-x guix-all-available-packages
@itemx M-x guix-newest-available-packages
Display all/newest available packages.

@item M-x guix-installed-packages
Display all installed packages.

@item M-x guix-obsolete-packages
Display obsolete packages (the packages that are installed in a profile
but cannot be found among available packages).

@item M-x guix-search-by-name
Display package(s) with the specified name.

@item M-x guix-search-by-regexp
Search for packages by a specified regexp.  By default ``name'',
``synopsis'' and ``description'' of the packages will be searched.  This
can be changed by modifying @code{guix-search-params} variable.

@end table

By default, these commands display each output on a separate line.  If
you prefer to see a list of packages---i.e., a list with a package per
line, use the following setting:

@example
(setq guix-package-list-type 'package)
@end example

Commands for displaying generations:

@table @kbd

@item M-x guix-generations
List all the generations.

@item M-x guix-last-generations
List the @var{N} last generations.  You will be prompted for the number
of generations.

@item M-x guix-generations-by-time
List generations matching time period.  You will be prompted for the
period using Org mode time prompt based on Emacs calendar (@pxref{The
date/time prompt,,, org, The Org Manual}).

@end table

You can also invoke the @command{guix pull} command (@pxref{Invoking
guix pull}) from Emacs using:

@table @kbd
@item M-x guix-pull
With @kbd{C-u}, make it verbose.
@end table

Once @command{guix pull} has succeeded, the Guix REPL is restared.  This
allows you to keep using the Emacs interface with the updated Guix.

@node Emacs General info
@subsubsection General information

The following keys are available for both ``list'' and ``info'' types of
buffers:

@table @kbd
@item l
@itemx r
Go backward/forward by the history of the displayed results (this
history is similar to the history of the Emacs @code{help-mode} or
@code{Info-mode}).

@item g
Revert current buffer: update information about the displayed
packages/generations and redisplay it.

@item R
Redisplay current buffer (without updating information).

@item C-c C-z
Go to the Guix REPL (@pxref{The REPL,,, geiser, Geiser User Manual}).

@item h
@itemx ?
Describe current mode to see all available bindings.

@end table

@emph{Hint:} If you need several ``list'' or ``info'' buffers, you can
simlpy @kbd{M-x clone-buffer} them, and each buffer will have its own
history.

@emph{Warning:} Name/version pairs cannot be used to identify packages
(because a name is not necessarily unique), so ``guix.el'' uses special
identifiers that live only during a guile session, so if the Guix REPL
was restarted, you may want to revert ``list'' buffer (by pressing
@kbd{g}).

@node Emacs List buffer
@subsubsection ``List'' buffer

An interface of a ``list'' buffer is similar to the interface provided
by ``package.el'' (@pxref{Package Menu,,, emacs, The GNU Emacs Manual}).

Default key bindings available for both ``package-list'' and
``generation-list'' buffers:

@table @kbd
@item m
Mark the current entry.
@item M
Mark all entries.
@item u
Unmark the current entry (with prefix, unmark all entries).
@item @key{DEL}
Unmark backward.
@item S
Sort entries by a specified column.
@end table

A ``package-list'' buffer additionally provides the following bindings:

@table @kbd
@item @key{RET}
Describe marked packages (display available information in a
``package-info'' buffer).
@item i
Mark the current package for installation.
@item d
Mark the current package for deletion.
@item U
Mark the current package for upgrading.
@item ^
Mark all obsolete packages for upgrading.
@item x
Execute actions on the marked packages.
@end table

A ``generation-list'' buffer additionally provides the following
bindings:

@table @kbd
@item @key{RET}
List packages installed in the current generation.
@item i
Describe marked generations (display available information in a
``generation-info'' buffer).
@item s
Switch profile to the current generation.
@item d
Mark the current generation for deletion (with prefix, mark all
generations).
@item x
Execute actions on the marked generations---i.e., delete generations.
@item e
Run Ediff (@pxref{Top,,, ediff, The Ediff Manual}) on package outputs
installed in the 2 marked generations.  With prefix argument, run Ediff
on manifests of the marked generations.
@item D
@itemx =
Run Diff (@pxref{Diff Mode,,, emacs, The GNU Emacs Manual}) on package
outputs installed in the 2 marked generations.  With prefix argument,
run Diff on manifests of the marked generations.
@item +
List package outputs added to the latest marked generation comparing
with another marked generation.
@item -
List package outputs removed from the latest marked generation comparing
with another marked generation.
@end table

@node Emacs Info buffer
@subsubsection ``Info'' buffer

The interface of an ``info'' buffer is similar to the interface of
@code{help-mode} (@pxref{Help Mode,,, emacs, The GNU Emacs Manual}).

``Info'' buffer contains some buttons (as usual you may use @key{TAB} /
@kbd{S-@key{TAB}} to move between buttons---@pxref{Mouse References,,,
emacs, The GNU Emacs Manual}) which can be used to:

@itemize @bullet
@item (in a ``package-info'' buffer)

@itemize @minus
@item install/remove a package;
@item jump to a package location;
@item browse home page of a package;
@item describe packages from ``Inputs'' fields.
@end itemize

@item (in a ``generation-info'' buffer)

@itemize @minus
@item remove a generation;
@item switch to a generation;
@item list packages installed in a generation;
@item jump to a generation directory.
@end itemize

@end itemize


@node Emacs Configuration
@subsection Configuration

There are many variables you can modify to change the appearance or
behavior of Emacs user interface.  Some of these variables are described
in this section.  Also you can use Custom Interface (@pxref{Easy
Customization,,, emacs, The GNU Emacs Manual}) to explore/set variables
(not all) and faces.

@menu
* Guile and Build Options: Emacs Build Options.	Specifying how packages are built.
* Buffer Names: Emacs Buffer Names.	Names of Guix buffers.
* Keymaps: Emacs Keymaps.		Configuring key bindings.
* Appearance: Emacs Appearance.		Settings for visual appearance.
@end menu

@node Emacs Build Options
@subsubsection Guile and Build Options

@table @code
@item guix-guile-program
If you have some special needs for starting a Guile process, you may set
this variable, for example:

@example
(setq guix-guile-program '("/bin/guile" "--no-auto-compile"))
@end example

@item guix-use-substitutes
Has the same meaning as @code{--no-substitutes} option (@pxref{Invoking
guix build}).

@item guix-dry-run
Has the same meaning as @code{--dry-run} option (@pxref{Invoking guix
build}).

@end table

@node Emacs Buffer Names
@subsubsection Buffer Names

Default names of ``guix.el'' buffers (``*Guix@tie{}@dots{}*'') may be
changed with the following variables:

@table @code
@item guix-package-list-buffer-name
@item guix-output-list-buffer-name
@item guix-generation-list-buffer-name
@item guix-package-info-buffer-name
@item guix-output-info-buffer-name
@item guix-generation-info-buffer-name
@item guix-repl-buffer-name
@item guix-internal-repl-buffer-name
@end table

By default, the name of a profile is also displayed in a ``list'' or
``info'' buffer name.  To change this behavior, use
@code{guix-buffer-name-function} variable.

For example, if you want to display all types of results in a single
buffer (in such case you will probably use a history (@kbd{l}/@kbd{r})
extensively), you may do it like this:

@example
(let ((name "Guix Universal"))
  (setq
   guix-package-list-buffer-name    name
   guix-output-list-buffer-name     name
   guix-generation-list-buffer-name name
   guix-package-info-buffer-name    name
   guix-output-info-buffer-name     name
   guix-generation-info-buffer-name name
   guix-buffer-name-function        #'guix-buffer-name-simple))
@end example

@node Emacs Keymaps
@subsubsection Keymaps

If you want to change default key bindings, use the following keymaps
(@pxref{Init Rebinding,,, emacs, The GNU Emacs Manual}):

@table @code
@item guix-list-mode-map
Parent keymap with general keys for ``list'' buffers.

@item guix-package-list-mode-map
Keymap with specific keys for ``package-list'' buffers.

@item guix-output-list-mode-map
Keymap with specific keys for ``output-list'' buffers.

@item guix-generation-list-mode-map
Keymap with specific keys for ``generation-list'' buffers.

@item guix-info-mode-map
Parent keymap with general keys for ``info'' buffers.

@item guix-package-info-mode-map
Keymap with specific keys for ``package-info'' buffers.

@item guix-output-info-mode-map
Keymap with specific keys for ``output-info'' buffers.

@item guix-generation-info-mode-map
Keymap with specific keys for ``generation-info'' buffers.

@end table

@node Emacs Appearance
@subsubsection Appearance

You can change almost any aspect of ``list'' / ``info'' buffers using
the following variables:

@table @code
@item guix-list-column-format
@itemx guix-list-column-titles
@itemx guix-list-column-value-methods
Specify the columns, their names, what and how is displayed in ``list''
buffers.

@item guix-info-displayed-params
@itemx guix-info-insert-methods
@itemx guix-info-ignore-empty-vals
@itemx guix-info-param-title-format
@itemx guix-info-multiline-prefix
@itemx guix-info-indent
@itemx guix-info-fill-column
@itemx guix-info-delimiter
Various settings for ``info'' buffers.

@end table


@node Emacs Pretty Path
@subsection Pretty SHA Path Mode

Along with ``guix.el'', GNU@tie{}Guix comes with ``pretty-sha-path.el''.
It provides a minor mode for abbreviating store paths by replacing
SHA-sequences of symbols with ``@dots{}'':

@example
/gnu/store/onecansee32lettersandnumbershere-foo-0.1  @result{}  /gnu/store/…-foo-0.1
@end example

Once you set up ``guix.el'' (@pxref{Emacs Initial Setup}), the following
commands become available:

@table @kbd

@item M-x pretty-sha-path-mode
Enable/disable prettifying for the current buffer.

@item M-x pretty-sha-path-global-mode
Enable/disable prettifying globally.

@end table

To automatically enable @code{pretty-sha-path-mode} globally on Emacs
start, add the following line to your init file:

@example
(pretty-sha-path-global-mode)
@end example

If you want to enable it only for specific major modes, add it to the
mode hooks (@pxref{Hooks,,, emacs, The GNU Emacs Manual}), for example:

@example
(add-hook 'shell-mode-hook 'pretty-sha-path-mode)
(add-hook 'dired-mode-hook 'pretty-sha-path-mode)
@end example