rebar3-proper: init at 0.12.1

pkgs/development/beam-modules/default.nix

@@ -21,8 +21,8 @@ let
       inherit (callPackage ../tools/build-managers/rebar3 { }) rebar3 rebar3WithPlugins;
       rebar = callPackage ../tools/build-managers/rebar { };
 
-      # rebar3 port compiler plugin is required by buildRebar3
       pc = callPackage ./pc { };
+      rebar3-proper = callPackage ./rebar3-proper { };
       rebar3-nix = callPackage ./rebar3-nix { };
 
       fetchHex = callPackage ./fetch-hex.nix { };

pkgs/development/beam-modules/rebar3-proper/default.nix

@@ -0,0 +1,13 @@
+{ lib, buildHex }:
+
+buildHex {
+  name = "rebar3_proper";
+  version = "0.12.1";
+  sha256 = "1f174fb6h2071wr7qbw9aqqvnglzsjlylmyi8215fhrmi38w94b6";
+
+  meta = {
+    description = "rebar3 proper plugin";
+    license = lib.licenses.bsd3;
+    homepage = "https://github.com/ferd/rebar3_proper";
+  };
+}