{
  lib,
  stdenv,
  callPackage,
  makeSetupHook,
  runCommand,
  tzdata,

  # Version specific stuff
  release,
  version,
  src,
  ...
}:

let
  baseInterp = stdenv.mkDerivation rec {
    pname = "tcl";
    inherit version src;

    outputs = [
      "out"
      "man"
    ];

    setOutputFlags = false;

    postPatch = ''
      substituteInPlace library/clock.tcl \
        --replace "/usr/share/zoneinfo" "${tzdata}/share/zoneinfo" \
        --replace "/usr/share/lib/zoneinfo" "" \
        --replace "/usr/lib/zoneinfo" "" \
        --replace "/usr/local/etc/zoneinfo" ""
    '';

    preConfigure = ''
      cd unix
    '';

    configureFlags = [
      "--enable-threads"
      # Note: using $out instead of $man to prevent a runtime dependency on $man.
      "--mandir=${placeholder "out"}/share/man"
      "--enable-man-symlinks"
      # Don't install tzdata because NixOS already has a more up-to-date copy.
      "--with-tzdata=no"
      "tcl_cv_strtod_unbroken=ok"
    ] ++ lib.optional stdenv.is64bit "--enable-64bit";

    enableParallelBuilding = true;

    postInstall =
      let
        dllExtension = stdenv.hostPlatform.extensions.sharedLibrary;
      in
      ''
        make install-private-headers
        ln -s $out/bin/tclsh${release} $out/bin/tclsh
        ln -s $out/lib/libtcl${release}${dllExtension} $out/lib/libtcl${dllExtension}
      '';

    meta = with lib; {
      description = "The Tcl scripting language";
      homepage = "https://www.tcl.tk/";
      license = licenses.tcltk;
      platforms = platforms.all;
      maintainers = with maintainers; [ agbrooks ];
    };

    passthru = rec {
      inherit release version;
      libPrefix = "tcl${release}";
      libdir = "lib/${libPrefix}";
      tclPackageHook = callPackage (
        { buildPackages }:
        makeSetupHook {
          name = "tcl-package-hook";
          propagatedBuildInputs = [ buildPackages.makeBinaryWrapper ];
          meta = {
            inherit (meta) maintainers platforms;
          };
        } ./tcl-package-hook.sh
      ) { };
      # verify that Tcl's clock library can access tzdata
      tests.tzdata = runCommand "${pname}-test-tzdata" { } ''
        ${baseInterp}/bin/tclsh <(echo "set t [clock scan {2004-10-30 05:00:00} \
                                      -format {%Y-%m-%d %H:%M:%S} \
                                      -timezone :America/New_York]") > $out
      '';
    };
  };

  mkTclDerivation = callPackage ./mk-tcl-derivation.nix { tcl = baseInterp; };

in
baseInterp.overrideAttrs (self: {
  passthru = self.passthru // {
    inherit mkTclDerivation;
  };
})