anchor.diff:    ]) ++ (with pkgs.haskellPackages; [
       # FIXME: Agda
       # FIXME: cabal2nix # NOTE: conflict with pandoc (and hpack and idris)
  -    # ghc
  +    ghc
       hpack
       idris
       # intero
  
positive.code:   nixpkgs.config.allowUnfree = true;
    # nixpkgs.config.allowBroken = true; # HACK
  
    nixpkgs.config.packageOverrides = super: let self = super.pkgs; in {
      # camlp5 = super.ocamlPackages.camlp5_6_strict;
      # camlp5 = super.ocamlPackages.camlp5_6_transitional;
  
negative.code:     };
      gap4r8p8 = super.callPackage ./pkgs/applications/science/math/gap/4r8p8.nix {};
      # NOTE: gcc = super.gcc6;
      # imagemagick = super.imagemagick7;
      jdk = super.openjdk8;
      # FIXME
  