gnu: Add ghc-unique.

* gnu/packages/haskell-xyz.scm (ghc-unique): New variable.
* gnu/packages/patches/ghc-unique-support-newer-hashable.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

Change-Id: Id9876b8018f5f8b3bcb82ab0bb13616ed298c31b

gnu/packages/haskell-xyz.scm

@@ -13387,6 +13387,31 @@ operations.  Uniplate has similar goals to the original Scrap Your Boilerplate
 work, but is substantially simpler and faster.")
     (license license:bsd-3)))
 
+(define-public ghc-unique
+  (package
+    (name "ghc-unique")
+    (version "0.4.7.9")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (hackage-uri "Unique" version))
+       (sha256
+        (base32 "14f1qnmhdmbam8qis725dhwq1mk9h86fsnzhkwhsx73ny9z29s1l"))
+       (patches (search-patches "ghc-unique-support-newer-hashable.patch"))))
+    (build-system haskell-build-system)
+    (properties '((upstream-name . "Unique")))
+    (inputs (list ghc-extra ghc-hashable ghc-unordered-containers))
+    (native-inputs (list ghc-hspec ghc-quickcheck))
+    (arguments
+     `(#:cabal-revision ("1"
+                         "10s0npnfkh7naj49afmyrvnilikp6426fbhi49f97pxrgcmy4dvw")))
+    (home-page "https://hackage.haskell.org/package/Unique")
+    (synopsis "Haskell functionality like \"uniq\" tool")
+    (description
+     "This library provides the functions to find unique and duplicate
+elements in a list.")
+    (license license:bsd-3)))
+
 (define-public ghc-unix-compat
   (package
     (name "ghc-unix-compat")