anchor.diff:    postInstall = ''
       mkdir -p $OCAMLFIND_DESTDIR/stublibs
       mv $OCAMLFIND_DESTDIR/labltk/dlllabltk.so $OCAMLFIND_DESTDIR/stublibs/
  +    for p in $out/bin/*
  +    do
  +      wrapProgram $p --set CAML_LD_LIBRARY_PATH $OCAMLFIND_DESTDIR/stublibs
  +    done
     '';
   
     meta = {
  
positive.code: { stdenv, lib, fetchurl, fetchzip, ocaml, findlib, tcl, tk }:
  
  let OCamlVersionAtLeast = lib.versionAtLeast ocaml.version; in
  
  if !OCamlVersionAtLeast "4.04"
  then throw "labltk is not available for OCaml ${ocaml.version}"
  else
  
  let param =
    let mkNewParam = { version, sha256 }: {
      inherit version;
      src = fetchzip {
        url = "https://github.com/garrigue/labltk/archive/${version}.tar.gz";
        inherit sha256;
      };
    }; in
    let mkOldParam = { version, key, sha256 }: {
      src = fetchurl {
        url = "https://forge.ocamlcore.org/frs/download.php/${key}/labltk-${version}.tar.gz";
        inherit sha256;
      };
      inherit version;
    }; in
   rec {
    "4.04" = mkOldParam {
      version = "8.06.2";
      key = "1628";
      sha256 = "1p97j9s33axkb4yyl0byhmhlyczqarb886ajpyggizy2br3a0bmk";
    };
    "4.05" = mkOldParam {
      version = "8.06.3";
      key = "1701";
      sha256 = "1rka9jpg3kxqn7dmgfsa7pmsdwm16x7cn4sh15ijyyrad9phgdxn";
    };
    "4.06" = mkOldParam {
      version = "8.06.4";
      key = "1727";
      sha256 = "0j3rz0zz4r993wa3ssnk5s416b1jhj58l6z2jk8238a86y7xqcii";
    };
    "4.07" = mkOldParam {
      version = "8.06.5";
      key = "1764";
      sha256 = "0wgx65y1wkgf22ihpqmspqfp95fqbj3pldhp1p3b1mi8rmc37zwj";
    };
    _8_06_7 = mkNewParam {
      version = "8.06.7";
  
negative.code:     version = "8.06.10";
      sha256 = "06cck7wijq4zdshzhxm6jyl8k3j0zglj2axsyfk6q1sq754zyf4a";
    };
   };
   param = params . ${lib.versions.majorMinor ocaml.version}
     or (throw "labltk is not available for OCaml ${ocaml.version}");
  in
  
  stdenv.mkDerivation rec {
    inherit (param) version src;
    name = "ocaml${ocaml.version}-labltk-${version}";
  
    buildInputs = [ ocaml findlib tcl tk makeWrapper ];
  
    configureFlags = [ "--use-findlib" "--installbindir" "$(out)/bin" ];
    dontAddPrefix = true;
  