anchor.diff: -{lib, stdenv, fetchurl, tk, tcllib, makeWrapper
  +{ lib
  +, stdenv
  +, fetchurl
  +, tk
  +, tcllib
  +, makeWrapper
   , tkremind ? true
  -} :
  +}:
   
   assert tkremind -> tk != null;
   assert tkremind -> tcllib != null;
  
positive.code:   tkremindPatch = optionalString tkremind ''
      substituteInPlace scripts/tkremind --replace "exec wish" "exec ${tk}/bin/wish"
    '';
  in stdenv.mkDerivation rec {
    pname = "remind";
    version = "03.03.05";
  
    src = fetchurl {
      url = "https://dianne.skoll.ca/projects/remind/download/remind-${version}.tar.gz";
      sha256 = "sha256-Ye0X2Gvek/pyaNVxGKL773OWJvC4I6F5nEsRQgzWbsE=";
    };
  
    nativeBuildInputs = optional tkremind makeWrapper;
  
negative.code:     wrapProgram $out/bin/tkremind --set TCLLIBPATH "${tclLibPaths}"
    '';
  
    meta = with lib; {
      homepage = "https://dianne.skoll.ca/projects/remind/";
      description = "Sophisticated calendar and alarm program for the console";
      license = licenses.gpl2Only;
      maintainers = with maintainers; [ raskin kovirobi ];
      platforms = platforms.unix;
    };
  }
  