gnu: Add ocaml-fmt.

* gnu/packages/ocaml.scm (ocaml-fmt): New variable.

gnu/packages/ocaml.scm

@@ -1227,3 +1227,31 @@ (define-public ocaml-cmdliner
 generation. It supports programs with single or multiple commands and respects
 most of the POSIX and GNU conventions.")
     (license license:bsd-3)))
+
+(define-public ocaml-fmt
+  (package
+    (name "ocaml-fmt")
+    (version "0.8.0")
+    (source
+      (origin
+        (method url-fetch)
+        (uri (string-append "http://erratique.ch/software/fmt/releases/fmt-"
+                            version ".tbz"))
+        (sha256 (base32
+                  "16y7ibndnairb53j8a6qgipyqwjxncn4pl9jiw5bxjfjm59108px"))))
+    (build-system ocaml-build-system)
+    (native-inputs `(("opam" ,opam)
+                     ("topkg" ,ocaml-topkg)))
+    (propagated-inputs `(("result" ,ocaml-result)
+                         ("cmdliner" ,ocaml-cmdliner)))
+    (arguments `(#:tests? #f
+                 #:build-flags (list "build" "--with-base-unix" "true"
+                                     "--with-cmdliner" "true")
+                 #:phases
+                 (modify-phases %standard-phases
+                   (delete 'configure))))
+    (home-page "http://erratique.ch/software/fmt")
+    (synopsis "OCaml Format pretty-printer combinators")
+    (description "Fmt exposes combinators to devise Format pretty-printing
+functions.")
+    (license license:isc)))