anchor.diff:        rev = "52b86bed1671321b25fe4d7495558f9f221b12aa";
         sha256 = "0hbnrwdgryr52170cfrlbiymr88jsyxilnpr343vnprqq3zk1xz0";
       };
  +    "8.9" = {
  +      version = "20190222";
  +      rev = "aa33052c1edfc5a65885942a67c2773b5d96f8cc";
  +      sha256 = "0mjgfdr9bzsch0dlk4vq1frkaig14dqh46r54cv0l15flxapg0iw";
  +    };
     }."${coq.coq-version}";
   
     continuations = mkContrib "continuations" [ ] {
  
positive.code:     sha256 = "1ddwzg12pbzpnz3njin4zhpph92kscrbsn3bzds26yj8fp76zc33";
    };
  
    containers = mkContrib "containers" [ "8.6" "8.7" "8.8" ] {
      "8.6" = {
        version = "8.6.0";
        rev = "fa1fec7";
  
negative.code: 
      buildInputs = with coq.ocamlPackages; [ ocaml camlp5 findlib coq ];
  
      installFlags =
         stdenv.lib.optional (stdenv.lib.versionAtLeast coq.coq-version "8.9") "-f Makefile.coq"
      ++ [ "COQLIB=$(out)/lib/coq/${coq.coq-version}/" ];
  
      passthru = {
        compatibleCoqVersions = v: builtins.elem v revs;
  