anchor.diff:  
       # .NET
       mono46
  -    fsharp
  +    unstable.fsharp41
       dotnetPackages.FSharpAutoComplete
       dotnetPackages.FSharpCompilerCodeDom
       dotnetPackages.FSharpCompilerService
  
positive.code: { config, pkgs, ... }:
  
  {
    nixpkgs.config = {
      packageOverrides = super: let self = super.pkgs; in {
        fsharp = super.fsharp.override {
          mono = pkgs.mono46;
        };
      };
    };
  
    environment.systemPackages = with pkgs; [
      # Tools
      gnumake
  
negative.code:     meld
  
      # Haskell
      unstable.stack
  
      # Go
      go
  