anchor.diff:    ] ++ (optionals (system == "x86_64-linux") [
       "ghcAndroidArm64"
       "ghcAndroidArmv7a"
  -  ]) ++ (optionals nixpkgs.stdenv.isDarwin [
  +  ]) ++ (optionals iosSupport [
       "ghcIosArm64"
     ]);
   
  
positive.code: 
    tryReflexPackages = generalDevTools ghc
      ++ builtins.map reflexEnv platforms
      ++ optional (system == "x86_64-darwin") iosReflexTodomvc
      ++ optional (system == "x86_64-linux") androidReflexTodomvc;
  
    demoVM = (import "${nixpkgs.path}/nixos" {
  
negative.code: , useTextJSString ? true
  , iosSdkVersion ? "10.2"
  }:
  let iosSdkLocation = "/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS${iosSdkVersion}.sdk";
      iosSupport = if nixpkgs.stdenv.isDarwin && builtins.pathExists iosSdkLocation
        then true
        else builtins.trace "Warning: No iOS sdk found at ${iosSdkLocation}; iOS support disabled.  To enable, either install a version of Xcode that provides that SDK or override the value of iosSdkVersion to match your installed version." false;
      globalOverlay = self: super: {
        all-cabal-hashes = super.all-cabal-hashes.override {
          src-spec = {
            owner = "commercialhaskell";
  