anchor.diff:  { config, pkgs, ... }:
   
  +let
  +  unstable = (import (fetchTarball https://github.com/NixOS/nixpkgs-channels/archive/nixos-unstable.tar.gz) {
  +    inherit (config.nixpkgs) config system;
  +  }).pkgs;
  +in
   {
  -  nixpkgs.config = {
  -    packageOverrides = super: let self = super.pkgs; in {
  -      fsharp = super.fsharp.override {
  -        mono = pkgs.mono46;
  -      };
  -    };
  -  };
  -
     environment.systemPackages = with pkgs; [
       # Tools
       gnumake
  
positive.code:     meld
  
      # Haskell
      stack
  
      # Go
      go
  
negative.code: 
      # .NET
      mono46
      unstable.fsharp41
      dotnetPackages.FSharpAutoComplete
      dotnetPackages.FSharpCompilerCodeDom
      dotnetPackages.FSharpCompilerService
  