buildDunePackage: new support function; use it to refactor some OCaml derivations

pkgs/development/ocaml-modules/ppxlib/default.nix

@@ -1,34 +1,26 @@
-{ stdenv, fetchFromGitHub, ocaml, findlib, dune
+{ stdenv, fetchFromGitHub, buildDunePackage
 , ocaml-compiler-libs, ocaml-migrate-parsetree, ppx_derivers, stdio
 }:
 
-stdenv.mkDerivation rec {
+buildDunePackage rec {
+  pname = "ppxlib";
   version = "0.3.1";
-  name = "ocaml${ocaml.version}-ppxlib-${version}";
 
   src = fetchFromGitHub {
     owner = "ocaml-ppx";
-    repo = "ppxlib";
+    repo = pname;
     rev = version;
     sha256 = "0qpjl84x8abq9zivifb0k8ld7fa1lrhkbajmmccvfv06ja3as1v4";
   };
 
-  buildInputs = [ ocaml findlib dune ];
-
   propagatedBuildInputs = [
     ocaml-compiler-libs ocaml-migrate-parsetree ppx_derivers stdio
   ];
 
-  buildPhase = "dune build";
-
-  inherit (dune) installPhase;
-
   meta = {
     description = "Comprehensive ppx tool set";
     license = stdenv.lib.licenses.mit;
     maintainers = [ stdenv.lib.maintainers.vbgl ];
     inherit (src.meta) homepage;
-    inherit (ocaml.meta) platforms;
   };
-
 }