Trying to set up Java dev. env.

# Nix expression for Java development.  Use `nix-shell --pure` and call
# `eclipse` from that.
let
  pkgs = import <nixpkgs> {};
  stdenv = pkgs.stdenv;
in rec {
  environment = stdenv.mkDerivation rec {
    name = "dev-env";
    version = "1";
    src = ./.;
    buildInputs = [
      pkgs.maven
      pkgs.openjdk
      # Doesn’t work: get the error `error: undefined variable ‘nixpkgs’ at …`
      # nixpkgs.javaPackages.junit_4_12
      (pkgs.eclipses.eclipseWithPlugins {
	eclipse = pkgs.eclipses.eclipse-sdk-46;
	plugins = [
	  # For JUnit, possibly some other stuff
	  pkgs.eclipses.plugins.jdt
	];
      })
    ];
  };
}