gnu: Add python-liblarch.

* gnu/packages/gnome.scm (python-liblarch): New variable.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

gnu/packages/gnome.scm

@@ -2501,6 +2501,47 @@ on the GNOME Desktop with a single simple application.")
 for settings shared by various components of the GNOME desktop.")
     (license license:lgpl2.1+)))
 
+(define-public python-liblarch
+  (package
+    (name "python-liblarch")
+    (version "3.0.1")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/getting-things-gnome/liblarch")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
+       (sha256
+        (base32 "0xv2mfvyzipbny3iz8vll77wsqxfwh28xj6bj1ff0l452waph45m"))))
+    (build-system python-build-system)
+    (arguments
+     `(#:phases
+       (modify-phases %standard-phases
+         (add-before 'check 'start-xserver
+           (lambda* (#:key inputs #:allow-other-keys)
+             (system (format #f "~a/bin/Xvfb :1 &"
+                             (assoc-ref inputs "xorg-server")))
+             (setenv "DISPLAY" ":1")
+             #t)))))
+    (native-inputs
+     `(("xorg-server" ,xorg-server-for-tests)))
+    (inputs
+     `(("gtk+" ,gtk+)))
+    (propagated-inputs
+     `(("python-pygobject" ,python-pygobject)))
+    (home-page "https://wiki.gnome.org/Projects/liblarch")
+    (synopsis "Library to easily handle complex data structures")
+    (description
+     "Liblarch is a Python library built to easily handle data structures such
+as lists, trees and acyclic graphs.  There's also a GTK binding that will
+allow you to use your data structure in a @code{Gtk.Treeview}.
+
+Liblarch support multiple views of one data structure and complex filtering.
+That way, you have a clear separation between your data themselves (Model)
+and how they are displayed (View).")
+    (license license:lgpl3+)))
+
 (define-public icon-naming-utils
   (package
     (name "icon-naming-utils")