gnu: Add emacs-spaceline.

* gnu/packages/emacs.scm (emacs-spaceline): New variable.

gnu/packages/emacs.scm

@@ -12323,3 +12323,35 @@ a better-looking, more functional Emacs mode-line.  A collection of predefined
 themes comes with the package.")
     (license license:gpl3+)))
 
+(define-public emacs-spaceline
+  (package
+    (name "emacs-spaceline")
+    (version "2.0.1")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/TheBB/spaceline.git")
+             (commit (string-append "v" version))))
+       (file-name (git-file-name name version))
+       (sha256
+        (base32
+         "1q8r95zfrh0vxna5ml2pq9b9f66clfqcl4d2qy2aizkvzyxg6skl"))))
+    (build-system emacs-build-system)
+    (propagated-inputs
+     `(("dash" ,emacs-dash)
+       ("powerline" ,emacs-powerline)
+       ("s" ,emacs-s)))
+    (home-page "https://github.com/TheBB/spaceline")
+    (synopsis "Powerline theme from Spacemacs")
+    (description "Spaceline provides Spacemacs' mode-line theme.
+This package provides features for three kinds of users.
+
+@itemize
+@item You just want to use the Spacemacs mode-line theme and forget about it.
+@item You want to use something similar to the Spacemacs mode-line theme, but
+with a handful of easy tweaks.
+@item You want an easy-to-use library for building your own mode-line from
+scratch, and you think the Spacemacs theme looks good.
+@end itemize")
+    (license license:gpl3+)))