anchor.diff: -{ nixpkgs ? import <nixpkgs> {}}:
  +{ nixpkgs ? import <nixpkgs> {}, ghc ? nixpkgs.haskell.compiler.ghc7103 }:
   
   with nixpkgs;
   with stdenv.lib;
  
positive.code: 
    jvmlibdir =
      if stdenv.isLinux
        then "${openjdk}/lib/openjdk/jre/lib/amd64/server"
        else "${openjdk}/jre/lib/server";
  in
  haskell.lib.buildStackProject {
    name = "sparkle";
    buildInputs =
      [ gradle
  
negative.code:       # to fetch distributed-closure
        git
        openssh
        ghc
      ];
    inherit ghc;
    extraArgs = ["--extra-lib-dirs=${jvmlibdir}"];
    # XXX Workaround https://ghc.haskell.org/trac/ghc/ticket/11042.
    LD_LIBRARY_PATH = [jvmlibdir];
  }
  