Language library packages should require language package

[Hartmut Goebel <h.goebel@crazy-compilers.com>]

Hi,

playing around with guix environment, I stepped over some weirdness The
weirdest of is (e.g.):

guix environment  --ad-hoc python-requests

will give you . . . . nothing.

Since python-requests does not have python as input, the package is
installed somewhere out of reach. This is even true when using a python
virtualenv prior to entering the guix environment (see below for details).

I assume, this is the same for perl and other languages.

So I propose to add python, perl, ... as an import for the "library"
packages of this language. This would be in the same line as .rpm and
.deb packages work.


Now the weirdness analysis:

$ cat echo_paths.sh
echo PATH=$PATH
echo PYTHONPATH=$PYTHONPATH
type python

Now let's set up "--ad-hoc python-requests" (but no python):

$ guix environment --pure --ad-hoc python-requests -- ./echo_paths.sh
PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.
PYTHONPATH=
python is /usr/bin/python

Wow, the system python is used, but where is python-requests? Maybe not
installed, since it already is in the system installation. Let's try a
virtual environment:

$ pyvenv /tmp/foo
$ source /tmp/foo/bin/activate
(foo)$ type python
python ist /tmp/foo/bin/python

(foo)$ guix environment --pure --ad-hoc python-requests -- ./echo_paths.sh
PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/bin:/sbin:.
PYTHONPATH=
python is /usr/bin/python

Huh? What? The virtual env was ignored (or dropped). Why this? Looks
like --pure resets the environment to something is thinks is correct,
even if if ist not adding anything to the environments.

Let's try without --pure:

(foo)$ guix environment  --ad-hoc python-requests -- ./echo_paths.sh
PATH=/tmp/foo/bin:/usr/local/bin:/usr/bin:/usr/local/games:/usr/games:/usr/lib64/qt4/bin:/usr/lib64/qt5/bin:/home/hartmut/bin:/home/hartmut/.local/bin
PYTHONPATH=/home/hartmut/lib/python
python is /tmp/foo/bin/python

Okay, this time I get the python within the virtual env. But still:
where is python-requests?

(foo)$ guix environment  --ad-hoc python-requests -- ls
/tmp/foo/lib/python3.4/site-packages/
easy_install.py  pip                  pkg_resources.py  setuptools
_markerlib       pip-6.1.1.dist-info  __pycache__      
setuptools-3.6.dist-info

It is not installed in the virtual environment either. Where is it?

-- 
Regards
Hartmut Goebel

| Hartmut Goebel          | h.goebel@crazy-compilers.com               |
| www.crazy-compilers.com | compilers which you thought are impossible |