gistfile1.js

grunt.registerTask("swf", function() {
  var done = this.async();
  var child = grunt.util.spawn({
    cmd : "mxmlc",
    args: ["-o", "coffee-collider-fallback.swf", "./src/fallback.as"]
  }, function(err, result) {
    if (result.code !== 0) {
      grunt.fail.fatal("Compile failed. See the above error message.");
    }
     done();
  });
  child.stdout.pipe(process.stdout);
  child.stderr.pipe(process.stderr);
});