* Steps to reproduce: $ python >>> from matplotlib import pyplot
* Full message: --8<---------------cut here---------------start------------->8--- Python 3.5.3 (default, Jan 1 1970, 00:00:01) [GCC 5.4.0] on linux Type "help", "copyright", "credits" or "license" for more information. >>> from matplotlib import pyplot Traceback (most recent call last): File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/backends/qt_compat.py", line 176, in <module> from PySide import QtCore, QtGui, __version__, __version_info__ ImportError: No module named 'PySide' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/pyplot.py", line 115, in <module> _backend_mod, new_figure_manager, draw_if_interactive, _show = pylab_setup() File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/backends/__init__.py", line 32, in pylab_setup globals(),locals(),[backend_name],0) File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/backends/backend_qt5agg.py", line 16, in <module> from .backend_qt5 import QtCore File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/backends/backend_qt5.py", line 26, in <module> import matplotlib.backends.qt_editor.figureoptions as figureoptions File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/backends/qt_editor/figureoptions.py", line 20, in <module> import matplotlib.backends.qt_editor.formlayout as formlayout File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/backends/qt_editor/formlayout.py", line 56, in <module> from matplotlib.backends.qt_compat import QtGui, QtWidgets, QtCore File "/home/fis/.guix-profile/lib/python3.5/site-packages/matplotlib/backends/qt_compat.py", line 179, in <module> "Matplotlib qt-based backends require an external PyQt4, PyQt5,\n" ImportError: Matplotlib qt-based backends require an external PyQt4, PyQt5, or PySide package to be installed, but it was not found. >>> --8<---------------cut here---------------end--------------->8--- * Platform Fedora 26 x86_64 * Guix version guix (GNU Guix) bad12e839c2f7823c45aa0121f7d5c9bb70905b7