Adds yojson.

Yojson is an optimized parsing and printing OCaml library for the JSON
format, contributed by Martin Jambon.

Webpage: http://mjambon.com/yojson.html

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

@@ -0,0 +1,32 @@
+{stdenv, fetchurl, ocaml, findlib, cppo, easy-format, biniou}:
+let
+  pname = "yojson";
+  version = "1.1.8";
+  webpage = "http://mjambon.com/${pname}.html";
+in
+stdenv.mkDerivation rec {
+
+  name = "${pname}-${version}";
+
+  src = fetchurl {
+    url = "http://mjambon.com/releases/${pname}/${name}.tar.gz";
+    sha256 = "0ayx17dimnpavdfyq6dk9xv2x1fx69by85vc6vl3nqxjkcv5d2rv";
+  };
+
+  buildInputs = [ ocaml findlib cppo easy-format biniou ];
+
+  createFindlibDestdir = true;
+
+  makeFlags = "PREFIX=$(out)";
+
+  preBuild = ''
+    mkdir $out/bin
+  '';
+
+  meta = {
+    description = "An optimized parsing and printing library for the JSON format";
+    homepage = "${webpage}";
+    license = stdenv.lib.licenses.bsd3;
+    platforms = ocaml.meta.platforms;
+  };
+}

pkgs/top-level/all-packages.nix

@@ -3279,6 +3279,8 @@ let
     opam_1_1 = callPackage ../development/tools/ocaml/opam/1.1.nix { };
     opam = opam_1_1;
 
+    yojson = callPackage ../development/ocaml-modules/yojson { };
+
     zarith = callPackage ../development/ocaml-modules/zarith { };
   };