+++
Categories = ["Emacs"]
Description = "Working out which package archives I'm using"
Tags = ["emacs"]
title = "Emacs Package Archive Statistics"
date = 2014-07-19T13:19:54Z
+++

I use [cask][] for managing the dependencies of my Emacs
configuration.  Whenever I opened my `Cask` file, I wondered if I
really was using all the sources I had defined:

{{< highlight cl >}}
(source gnu)
(source marmalade)
(source melpa)
(source melpa-stable)
(source org)
{{< /highlight >}}

It seemed quite strange that we have so many package repositories in
the Emacs world and I'm not even using all of them.  I find this state
less than ideal, much as
[Jorgen Schäfer details][state of emacs package archives].  My ideal
package repository would be once that works with VCS releases, mostly
because it's a much simpler process to work with than having to sign
up to yet another website just to upload a package, then ensure it's
kept up-to-date on every release.

As such, I prefer the concepts behing [MELPA][] and [MELPA Stable][] to
those of [Marmalade][].  [GNU ELPA][] doesn't appear to allow any
submissions and [org][org archive] is specific to [org-mode].  I've
also noticed that many packages I find and use are on github and so
work with the [MELPA][] system.  However, I don't like [MELPA's][MELPA]
versioning: it just gets the latest code and puts the build date in
the version, meaning that packages could break at any time.

So, ideally I would use [MELPA Stable][] as much as possible and reduce my
usage of [Marmalade][] and [MELPA][].  [GNU ELPA][] doesn't appear to have
many packages, but I wasn't sure if I was using any.
I couldn't see the information listed in the `*Packages*` buffer, so I
decided to try to figure out how to generate some usage statistics.

I found [how to get a list of installed packages][], but that just gives
a list:

{{< highlight cl >}}
(ace-jump-mode ag auto-compile auto-indent-mode autopair ...)
{{< /highlight >}}

I needed to get more information about those packages.  I looked at
where `list-packages` gets that information from.  It seems that
`package-archive-contents` is a list of cons cells:

{{< highlight cl >}}
(org-plus-contrib .
				  [(20140714)
				  nil "Outline-based notes management and organizer" tar "org"])
{{< /highlight >}}

Then created a function to loop over the contents of
`package-activated-list`, retrieving the corresponding contents of
`package-archive-contents`:

{{< highlight cl >}}
(defun package-list-installed ()
  (loop for pkg in package-activated-list
        collect (assq pkg package-archive-contents)))
{{< /highlight >}}

This generates a list of arrays from `package-archive-contents`.
There are some helper functions in package.el such as
`package-desc-kind`.  `package-desc-archive` was exactly what I
needed.  I happened to be using a pretest version of Emacs at the time
and didn't know that it's not in 24.3, so I just made sure it was defined:

{{< highlight cl >}}
(if (not (fboundp #'package-desc-archive))
    (defsubst package-desc-archive (desc)
      (aref desc (1- (length desc)))))
{{< /highlight >}}

Weirdly, some of the arrays (seemingly the ones from the
[org archive][]) had a different length, but the repository/archive was
always the last element, which is why I used `(1- (length ))` and not
a constant, like the other `package-desc-*` functions.

To generate a list of statistics, I just needed to loop over the
installed packages from `package-list-installed` and update a count
for each archive:

{{< highlight cl >}}
(defun package-archive-stats ()
  (let ((archives (makehash))
        (assoc '()))
    (dolist (arc package-archives)
      (puthash (car arc) 0 archives))
    (maphash (lambda (k v)
               (setq assoc (cons (cons k v) assoc)))
             (dolist (pkg (-filter #'identity (package-list-installed)) archives)
               (let ((pkg-arc (package-desc-archive (cdr pkg))))
                 (incf (gethash pkg-arc archives)))))
    assoc))
{{< /highlight >}}

Running this gives a list of cons cells:

{{< highlight cl >}}
(("gnu" . 0)
 ("org" . 1)
 ("melpa-stable" . 2)
 ("melpa" . 106)
 ("marmalade" . 1))
{{< /highlight >}}

I wrapped it in an interactive function so that I could check the
numbers quickly:

{{< highlight cl >}}
(defun package-show-archive-stats ()
  (interactive)
  (message "%s" (package-archive-stats)))
{{< /highlight >}}

With that, I removed `(source gnu)` from my `Cask` file.  Now I had
another question.  What package was installed from [marmalade][]?  In
the lisp fashion, I created yet another function:

{{< highlight cl >}}
(defun package-show-installed-from-archive (archive)
  (interactive (list (helm-comp-read "Archive: " (mapcar #'car package-archives)
                                      :must-match t)))
  (let ((from-arc (mapcar #'car
                          (--filter (equalp (package-desc-archive (cdr it)) archive)
                                    (package-list-installed)))))
    (if (called-interactively-p)
        (message "%s" from-arc)
      from-arc)))
{{< /highlight >}}
(Non-helm users can replace `helm-comp-read` with
`ido-completing-read` or similar)

Running this with the argument `"marmalade"` gives:

{{< highlight cl >}}
(php-extras)
{{< /highlight >}}

I checked on [MELPA Stable][] and [MELPA][], but it's not available
there.  Given that I use [php-extras][] quite a bit at work, I can't remove
[marmalade][] just yet.  However, as it's a git repository, it should be
easy for me to create a recipe for MELPA.  Then I can remove marmalade
from my [cask][] configuration.  Hooray for simplification!

Hopefully, packaging in Emacs will become simpler in the future.
There are some interesting things in 24.4 like pinning packages to a
repository, which would allow [MELPA Stable][] to be used even when
[MELPA][] defines the same package with a higher "version".

[cask]: https://github.com/cask/cask/
[state of emacs package archives]: http://blog.jorgenschaefer.de/2014/06/the-sorry-state-of-emacs-lisp-package.html
[marmalade]: http://marmalade-repo.org/
[GNU ELPA]: http://elpa.gnu.org/packages/
[MELPA]: http://hiddencameras.milkbox.net/
[MELPA Stable]: http://melpa-stable.milkbox.net/
[org archive]: http://orgmode.org/elpa.html
[how to get a list of installed packages]: http://stackoverflow.com/questions/13866848/how-to-save-a-list-of-all-the-installed-packages-in-emacs-24
[php-extras]: https://github.com/arnested/php-extras
[org-mode]: http://orgmode.org/