anchor.diff:      , executable ? false # run chmod +x ?
       , destination ? ""   # relative path appended to $out eg "/bin/foo"
       }:
  +    if executable == false && destination == "" then
  +      writeText name text
  +    else
       runCommand name
         { inherit text executable;
           passAsFile = [ "text" ];
  
positive.code:       inherit name buildCommand;
      } // env);
  
  
    # Create a single file.
    writeTextFile =
  
negative.code: 
  
    # Shorthands for `writeTextFile'.
    writeTextDir = name: text: writeTextFile {inherit name text; destination = "/${name}";};
    writeScript = name: text: writeTextFile {inherit name text; executable = true;};
    writeScriptBin = name: text: writeTextFile {inherit name text; executable = true; destination = "/bin/${name}";};
  