gnu: Add julia-datavalues.

* gnu/packages/julia-xyz.scm (julia-datavalues-0.4.12): New variable.

gnu/packages/julia-xyz.scm

@@ -470,3 +470,25 @@ package taking a dependency on it.  As such, it is paramount for
 @code{DataAPI.jl} to be as minimal as possible, defining only generic function
 stubs and very little else.")
     (license license:expat)))
+
+(define-public julia-datavalues
+  (package
+    (name "julia-datavalues")
+    (version "0.4.12")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/queryverse/DataValues.jl")
+             (commit (string-append "v" version))))
+       (file-name "DataValues")
+       (sha256
+        (base32 "1x0si392psc6drc1x9vnzln4ai4y483n639yd7wqkn5h1nsxaa1c"))))
+    (propagated-inputs `(("julia-datavalueinterfaces"
+                          ,julia-datavalueinterfaces)))
+    (build-system julia-build-system)
+    (home-page "https://github.com/queryverse/DataValues.jl")
+    (synopsis "Missing values for Julia")
+    (description "This package provides the type DataValue that is used to
+represent missing data.")
+    (license license:expat)))