gnu: Add ocaml-ppx-pipebang.

* gnu/packages/ocaml.scm (ocaml-ppx-pipebang): New variable.
(ocaml4.07-ppx-pipebang): Inherit from it.

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

gnu/packages/ocaml.scm

@@ -5888,9 +5888,34 @@ where one needs to construct a s-expression based on various element of the
 context such as function arguments.")
     (license license:asl2.0)))
 
-(define-public ocaml4.07-ppx-pipebang
+(define-public ocaml-ppx-pipebang
   (package
-    (name "ocaml4.07-ppx-pipebang")
+    (name "ocaml-ppx-pipebang")
+    (version "0.14.0")
+    (source
+      (origin
+        (method git-fetch)
+        (uri (git-reference
+               (url "https://github.com/janestreet/ppx_pipebang")
+               (commit (string-append "v" version))))
+        (file-name (git-file-name name version))
+        (sha256
+          (base32 "0450b3p2rpnnn5yyvbkcd3c33jr2z0dp8blwxddaj2lv7nzl5dzf"))))
+    (build-system dune-build-system)
+    (arguments `(#:tests? #f)); no tests
+    (propagated-inputs (list ocaml-ppxlib))
+    (properties `((upstream-name . "ppx_pipebang")
+                  (ocaml4.07-variant . ,(delay ocaml4.07-ppx-pipebang))))
+    (home-page "https://github.com/janestreet/ppx_pipebang")
+    (synopsis "Inline reverse application operators `|>` and `|!`")
+    (description "A ppx rewriter that inlines reverse application operators
+@code{|>} and @code{|!}.")
+    (license license:expat)))
+
+(define-public ocaml4.07-ppx-pipebang
+  (package-with-ocaml4.07
+    (package
+      (inherit ocaml-ppx-pipebang)
       (version "0.11.0")
       (source (origin
                 (method url-fetch)
@@ -5900,23 +5925,9 @@ context such as function arguments.")
                 (sha256
                  (base32
                   "1wrrzlb4kdvkkcmzi01fw25jar38r2jlnyn0i6pn4z0lq4gpm9m0"))))
-    (build-system dune-build-system)
+      (propagated-inputs (list ocaml-migrate-parsetree ocaml-ppxlib))
-    (arguments
+      (properties '())
-     ;; No tests
+      (license license:asl2.0))))
-     `(#:tests? #f
-       #:ocaml ,ocaml-4.07
-       #:findlib ,ocaml4.07-findlib
-       #:dune ,ocaml4.07-dune))
-    (propagated-inputs
-      `(("ocaml-migrate-parsetree"
-         ,(package-with-ocaml4.07 ocaml-migrate-parsetree))
-        ("ocaml-ppxlib" ,(package-with-ocaml4.07 ocaml-ppxlib))))
-    (properties `((upstream-name . "ppx_pipebang")))
-    (home-page "https://github.com/janestreet/ppx_pipebang")
-    (synopsis "Inline reverse application operators `|>` and `|!`")
-    (description "A ppx rewriter that inlines reverse application operators
-@code{|>} and @code{|!}.")
-    (license license:asl2.0)))
 
 (define-public ocaml-ppx-optional
   (package