anchor.diff:  
     meta = with lib; {
       inherit (anki.meta) license homepage description longDescription;
  -    platforms = [ "x86_64-linux" ];
  +    platforms = [ "x86_64-linux" "x86_64-darwin" ];
       maintainers = with maintainers; [ atemu ];
     };
   in
   
  -buildFHSUserEnv (appimageTools.defaultFhsEnvArgs // {
  +if stdenv.isLinux then buildFHSUserEnv (appimageTools.defaultFhsEnvArgs // {
     name = "anki";
   
     runScript = writeShellScript "anki-wrapper.sh" ''
  
positive.code: { fetchurl, stdenv, lib, buildFHSUserEnv, appimageTools, writeShellScript, anki }:
  
  let
    pname = "anki-bin";
    version = "2.1.36";
  
    unpacked = stdenv.mkDerivation {
  
negative.code:   '';
  
    inherit meta;
  }) else stdenv.mkDerivation {
    inherit pname version;
  
    src = fetchurl {
      url = "https://github.com/ankitects/anki/releases/download/${version}/anki-${version}-mac.dmg";
      sha256 = "1i6iidm5h8r9g801mvqxi2av03qdw3lr28056fv5ixnb5dq2wqim";
    };
  
    nativeBuildInputs = [ undmg ];
    sourceRoot = ".";
  
    installPhase = ''
      mkdir -p $out/Applications/
      cp -a Anki.app $out/Applications/
    '';
  
    inherit meta;
  }
  