anchor.diff: -{ lib, callPackage, newScope
  +{ lib, callPackage, newScope, recurseIntoAttrs
   , gnumake3
   , ocamlPackages_3_12_1
   , ocamlPackages_4_02
  
positive.code:       paco = callPackage ../development/coq-modules/paco {};
        QuickChick = callPackage ../development/coq-modules/QuickChick {};
        ssreflect = callPackage ../development/coq-modules/ssreflect { };
        contribs = callPackage ../development/coq-modules/contribs { };
      };
  
    filterCoqPackages = coq:
      lib.filterAttrs
      (_: p:
        let pred = p.compatibleCoqVersions or (_: true);
        in pred coq.coq-version
  
negative.code:     let callPackage = newScope self ; in rec {
        inherit callPackage coq;
        coqPackages = self;
  
        contribs = recurseIntoAttrs
          (callPackage ../development/coq-modules/contribs {});
  
        autosubst = callPackage ../development/coq-modules/autosubst {};
        bignums = if lib.versionAtLeast coq.coq-version "8.6"
  