@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.
* Prettify Mode: Emacs Prettify.	Abbreviating @file{/gnu/store/@dots{}} file names.
* Completions: Emacs Completions.       Completing @command{guix} shell command.
@end menu

@node Emacs Initial Setup
@subsection Initial Setup

On the Guix System Distribution (@pxref{GNU Distribution}), ``guix.el''
is ready to use, provided Guix is installed system-wide, which is the
case by default.  So if that is what you're using, you can happily skip
this section and read about the fun stuff.

If you're not yet a happy user of GuixSD, a little bit of setup is needed.
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 ``guix.el'' may be configured by requiring a special
@code{guix-init} file---i.e., by adding the following code into your
init file (@pxref{Init File,,, emacs, The GNU Emacs Manual}):

@example
(add-to-list 'load-path "/path/to/directory-with-guix.el")
(require 'guix-init nil t)
@end example

So the only thing you need to figure out is where the directory with
elisp files for Guix is placed.  It depends on how you installed Guix:

@itemize
@item
If it was installed by a package manager of your distribution or by a
usual @code{./configure && make && make install} command sequence, then
elisp files are placed in a standard directory with Emacs packages
(usually it is @file{/usr/share/emacs/site-lisp/}), which is already in
@code{load-path}, so there is no need to add that directory there.

@item
If you used a binary installation method (@pxref{Binary Installation}),
then Guix is installed somewhere in the store, so the elisp files are
placed in @file{/gnu/store/@dots{}-guix-0.8.2/share/emacs/site-lisp/} or
alike.  However it is not recommended to refer directly to a store
directory.  Instead you can install Guix using Guix itself with
@command{guix package -i guix} command (@pxref{Invoking guix package})
and add @file{~/.guix-profile/share/emacs/site-lisp/} directory to
@code{load-path} variable.

@item
If you did not install Guix at all and prefer a hacking way
(@pxref{Running Guix Before It Is Installed}), along with augmenting
@code{load-path} you need to set @code{guix-load-path} variable to the
same directory, so your final configuration will look like this:

@example
(let ((dir "/path/to/your-guix-git-tree/emacs"))
  (add-to-list 'load-path dir)
  (setq guix-load-path dir))
(require 'guix-init nil t)
@end example
@end itemize

By default, along with autoloading (@pxref{Autoload,,, elisp, The GNU
Emacs Lisp Reference Manual}) the main interactive commands for
``guix.el'' (@pxref{Emacs Commands}), requiring @code{guix-init} will
also autoload commands for the Emacs packages installed in your user
profile.

To disable automatic loading of installed Emacs packages, set
@code{guix-package-enable-at-startup} variable to @code{nil} before
requiring @code{guix-init}.  This variable has the same meaning for
Emacs packages installed with Guix, as @code{package-enable-at-startup}
for the built-in Emacs package system (@pxref{Package Installation,,,
emacs, The GNU Emacs Manual}).

You can activate Emacs packages installed in your profile whenever you
want using @kbd{M-x@tie{}guix-emacs-load-autoloads}.

@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 M
Apply manifest to the current profile or to a specified profile, if
prefix argument is used.  This has the same meaning as @code{--manifest}
option (@pxref{Invoking guix package}).

@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 (with prefix, 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 e
Edit the definition of the curent package (go to its location).  This is
similar to @command{guix edit} command (@pxref{Invoking guix edit}), but
for opening a package recipe in the current Emacs instance.
@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

It is also possible to copy a button label (a link to an URL or a file)
by pressing @kbd{c} on a button.


@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-root-map
Parent keymap with general keys for all guix modes.

@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.

@item guix-info-button-map
Keymap with keys available when a point is placed on a button.

@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 Prettify
@subsection Guix Prettify Mode

Along with ``guix.el'', GNU@tie{}Guix comes with ``guix-prettify.el''.
It provides a minor mode for abbreviating store file names by replacing
hash sequences of symbols with ``@dots{}'':

@example
/gnu/store/72f54nfp6g1hz873w8z3gfcah0h4nl9p-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 guix-prettify-mode
Enable/disable prettifying for the current buffer.

@item M-x global-guix-prettify-mode
Enable/disable prettifying globally.

@end table

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

@example
(global-guix-prettify-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 'guix-prettify-mode)
(add-hook 'dired-mode-hook 'guix-prettify-mode)
@end example


@node Emacs Completions
@subsection Shell Completions

Another feature that becomes available after configuring Emacs interface
(@pxref{Emacs Initial Setup}) is completing of @command{guix}
subcommands, options, packages and other things in @code{shell}
(@pxref{Interactive Shell,,, emacs, The GNU Emacs Manual}) and
@code{eshell} (@pxref{Top,,, eshell, Eshell: The Emacs Shell}).

It works the same way as other completions do.  Just press @key{TAB}
when your intuition tells you.

And here are some examples, where pressing @key{TAB} may complete
something:

@itemize @w{}

@item @code{guix pa}@key{TAB}
@item @code{guix package -}@key{TAB}
@item @code{guix package --}@key{TAB}
@item @code{guix package -i gei}@key{TAB}
@item @code{guix build -L/tm}@key{TAB}
@item @code{guix build --sy}@key{TAB}
@item @code{guix build --system=i}@key{TAB}
@item @code{guix system rec}@key{TAB}
@item @code{guix lint --checkers=sy}@key{TAB}
@item @code{guix lint --checkers=synopsis,des}@key{TAB}

@end itemize
