From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jan Nieuwenhuizen <janneke@gnu.org>
Subject: Re: Guix and Emacs Integration for Polyglot Development
Date: Thu, 13 Sep 2018 22:45:19 +0200
Message-ID: <875zz9gm8w.fsf@gnu.org>
References: <87wos9rp5y.fsf@gnu.org> <87wos5cma6.fsf@gnu.org>
	<87tvn9s14w.fsf@gnu.org> <87k1o5b05d.fsf@gnu.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
Return-path: <help-guix-bounces+gcggh-help-guix=m.gmane.org@gnu.org>
Received: from eggs.gnu.org ([2001:4830:134:3::10]:38746)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <janneke@gnu.org>) id 1g0YUt-0004OM-6T
	for help-guix@gnu.org; Thu, 13 Sep 2018 16:45:56 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <janneke@gnu.org>) id 1g0YUr-00074g-OF
	for help-guix@gnu.org; Thu, 13 Sep 2018 16:45:54 -0400
In-Reply-To: <87k1o5b05d.fsf@gnu.org> ("Ludovic
	\=\?utf-8\?Q\?Court\=C3\=A8s\=22'\?\=
	\=\?utf-8\?Q\?s\?\= message of "Sat, 01 Sep 2018 19:25:18 +0200")
List-Id: <help-guix.gnu.org>
List-Unsubscribe: <https://lists.gnu.org/mailman/options/help-guix>,
	<mailto:help-guix-request@gnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/archive/html/help-guix/>
List-Post: <mailto:help-guix@gnu.org>
List-Help: <mailto:help-guix-request@gnu.org?subject=help>
List-Subscribe: <https://lists.gnu.org/mailman/listinfo/help-guix>,
	<mailto:help-guix-request@gnu.org?subject=subscribe>
Errors-To: help-guix-bounces+gcggh-help-guix=m.gmane.org@gnu.org
Sender: "Help-Guix" <help-guix-bounces+gcggh-help-guix=m.gmane.org@gnu.org>
To: Ludovic =?utf-8?Q?Court=C3=A8s?= <ludo@gnu.org>
Cc: help-guix@gnu.org

Ludovic Court=C3=A8s writes:

> In all modesty ;-) I think the API is rather good:
>
> scheme@(guile-user)> ,use(guix profiles)
> scheme@(guile-user)> (profile-search-paths "/home/ludo/.guix-profile")
> $11 =3D ((#<<search-path-specification> variable: "PATH" files: ("bin" "s=
bin") separator: ":" file-type: directory file-pattern: #f> . "/home/ludo/.=
guix-profile/bin:/home/ludo/.guix-profile/sbin") (#<<search-path-specificat=
ion> variable: "PYTHONPATH" files: ("lib/python3.6/site-packages") separato=
r: ":" file-type: directory file-pattern: #f> . "/home/ludo/.guix-profile/l=
ib/python3.6/site-packages") =E2=80=A6

Whoa, that helps!  Is it just me who is so dense -- I really think this
REPL'y power of Guix is much under-appreciated and would deserve
more attention.

So, what about (thanks to Ricardo via #guile irc and wasamasa via #emacs)

--8<---------------cut here---------------start------------->8---
(defun guix-switch-profile (&optional profile)
  "Switch Emacs' environment to PROFILE.  PROFILE can be a named
profile (like ~/.guix-profile, ~/.config/guix/work) or an
environment (like: echo $GUIX_ENVIRONMENT)."

  (interactive "fprofile: ")
  (lexical-let* ((guix-program
                  `(begin
                    (use-modules (ice-9 match)
                                 (guix profiles)
                                 (guix search-paths))
                    (let ((specs (profile-search-paths ,(expand-file-name p=
rofile))))
                      (map
                       (match-lambda ((spec . dir)
                                      (list (search-path-specification-vari=
able spec)
                                            (or (search-path-specification-=
separator spec) "")
                                            dir)))
                       specs))))
                 (guix-output (guix-eval (format "%S" guix-program)))
                 (profile-sexp (car (read-from-string (car guix-output)))))
    (mapcar*
     (lambda (variable separator path)
       (lexical-let ((value (cond ((string-empty-p separator) path)
                                  ((getenv variable) (concat path separator=
 (getenv variable)))
                                  (t path))))
         (setenv variable value)))
     (mapcar #'car profile-sexp)
     (mapcar #'cadr profile-sexp)
     (mapcar #'caddr profile-sexp))))
--8<---------------cut here---------------end--------------->8---

and where to put this?

janneke