gnu: Add ghc-microlens-th.

* gnu/packages/haskell.scm (ghc-microlens-th): New variable.

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

gnu/packages/haskell.scm

@@ -9346,4 +9346,29 @@ combinators (like @code{failing} and @code{singular}), but everything else is
 stripped.  As the result, this package has no dependencies.")
     (license license:bsd-3)))
 
+(define-public ghc-microlens-th
+  (package
+    (name "ghc-microlens-th")
+    (version "0.4.1.3")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append "https://hackage.haskell.org/package/"
+                           "microlens-th-" version "/"
+                           "microlens-th-" version ".tar.gz"))
+       (sha256
+        (base32
+         "15a12cqxlgbcn1n73zwrxnp2vfm8b0ma0a0sdd8zmjbs8zy3np4f"))))
+    (build-system haskell-build-system)
+    (inputs `(("ghc-microlens" ,ghc-microlens)))
+    (home-page
+     "https://github.com/aelve/microlens")
+    (synopsis "Automatic generation of record lenses for
+@code{ghc-microlens}")
+    (description "This Haskell package lets you automatically generate lenses
+for data types; code was extracted from the lens package, and therefore
+generated lenses are fully compatible with ones generated by lens (and can be
+used both from lens and microlens).")
+    (license license:bsd-3)))
+
 ;;; haskell.scm ends here