ocaml-packages: add zarith 1.2.1

Signed-off-by: Austin Seipp <[e-mail]>

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

···
+{ stdenv, fetchurl, ocaml, findlib, pkgconfig, gmp, perl }:
+
+let
+  ocaml_version = (builtins.parseDrvName ocaml.name).version;
+in
+stdenv.mkDerivation rec {
+  name = "zarith-${version}";
+  version = "1.2.1";
+
+  src = fetchurl {
+    url = "http://forge.ocamlcore.org/frs/download.php/1199/${name}.tgz";
+    sha256 = "0i21bsx41br0jgw8xmlpnky5zamzqkpbykrq0z53z7ar77602s4i";
+  };
+
+  buildInputs = [ ocaml findlib pkgconfig gmp perl ];
+
+  configurePhase = ''
+    ./configure -installdir $out/lib/ocaml/${ocaml_version}/site-lib
+  '';
+  preInstall = "mkdir -p $out/lib/ocaml/${ocaml_version}/site-lib";
+
+  meta = {
+    description = "fast, arbitrary precision OCaml integers";
+    homepage    = "http://forge.ocamlcore.org/projects/zarith";
+    license     = stdenv.lib.licenses.lgpl2;
+    platforms   = ocaml.meta.platforms;
+    maintainers = [ stdenv.lib.maintainers.thoughtpolice ];
+  };
+}

pkgs/top-level/all-packages.nix

···
     opam_1_0_0 = callPackage ../development/tools/ocaml/opam/1.0.0.nix { };
     opam_1_1 = callPackage ../development/tools/ocaml/opam/1.1.nix { };
     opam = opam_1_1;
+
+    zarith = callPackage ../development/ocaml-modules/zarith { };
   };
 
   ocamlPackages = recurseIntoAttrs ocamlPackages_4_01_0;