anchor.diff:    exposeAllUnfoldings = import ./expose-all-unfoldings.nix { };
   
     # For GHC and GHCJS
  -  any = _: _: {};
  +  any = _: _: { };
     any-8 = import ./any-8.nix { inherit haskellLib lib getGhcVersion; };
     any-8_6 = import ./any-8.6.nix { inherit haskellLib fetchFromGitHub; inherit (nixpkgs) pkgs; };
     any-head = import ./any-head.nix { inherit haskellLib fetchFromGitHub; };
   
     # Just for GHC, usually to sync with GHCJS
  -  ghc-8_6 = _: _: {};
  -  ghc-head = _: _: {};
  +  ghc-8_6 = _: _: { };
  +  ghc-head = _: _: { };
   
     profiling = import ./profiling.nix {
       inherit haskellLib;
  
positive.code: 
      (optionalExtension enableExposeAllUnfoldings exposeAllUnfoldings)
  
      combined-any
      (optionalExtension (!(super.ghc.isGhcjs or false)) combined-ghc)
      (optionalExtension (super.ghc.isGhcjs or false) combined-ghcjs)
  
negative.code:     (optionalExtension useTextJSString textJSString-8_6)
      (optionalExtension useTextJSString ghcjs-textJSString-8_6)
      (optionalExtension useFastWeak ghcjs-fast-weak_8_6)
    ]
      self
      super;
  
    combined-ghcjs-8_10 = self: super: foldExtensions [
      (optionalExtension useTextJSString textJSString)
      (optionalExtension useTextJSString textJSString-8_10)
      (optionalExtension useTextJSString ghcjs-textJSString-8_10)
      (optionalExtension useFastWeak ghcjs-fast-weak_8_10)
    ]
      self
      super;
  
    ##
    ## Constituent
  