gnu: Add Data::Stag.

* gnu/packages/perl.scm (perl-data-stag): New variable.

gnu/packages/perl.scm

@@ -1118,6 +1118,30 @@ (define-public perl-data-page
 The maths behind this is unfortunately fiddly, hence this module.")
     (license (package-license perl))))
 
+(define-public perl-data-stag
+  (package
+    (name "perl-data-stag")
+    (version "0.14")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append "mirror://cpan/authors/id/C/CM/CMUNGALL/"
+                           "Data-Stag-" version ".tar.gz"))
+       (sha256
+        (base32
+         "0ncf4l39ka23nb01jlm6rzxdb5pqbip01x0m38bnvf1gim825caa"))))
+    (build-system perl-build-system)
+    (propagated-inputs
+     `(("perl-io-string" ,perl-io-string)))
+    (home-page "http://search.cpan.org/dist/Data-Stag")
+    (synopsis "Structured tags datastructures")
+    (description
+     "This module is for manipulating data as hierarchical tag/value
+pairs (Structured TAGs or Simple Tree AGgreggates).  These datastructures can
+be represented as nested arrays, which have the advantage of being native to
+Perl.")
+    (license (package-license perl))))
+
 (define-public perl-data-stream-bulk
   (package
     (name "perl-data-stream-bulk")