Broccoli may be easier to understand if you think of it functionally

Brocfile.js

//
// Broccoli may be easier to understand if you think of it functionally
//
// This is an incomplete Brocfile.js! Not even sure if it's valid.
// Adapted from http://ampersate.com/getting-started-with-broccoli-and-emberjs 
//
// Note: This would probably look nicer in CoffeeScript
// Note: This would probably look best in ClojureScript
//

var appjs =
	compileES6(
		new broccoli.MergedTree([
			/* config tree */
			preprocess(
				pickFiles(broccoli.makeTree('config'), {
					srcDir: '/',
					destDir: 'config'
				})),
			/* app tree */
			preprocess(
				pickFiles(broccoli.makeTree('app'), {
					srcDir: '/',
					destDir: 'app'
				})),
			/* vendor tree */
			broccoli.makeTree('vendor')
			]
			.concat(
			  /* bower tree */
			  broccoli.bowerTrees())),
		/* options */
		{
			loaderFile: 'loader.js',
			ignoredModules: [
			    'resolver'
			],
			inputFiles: [
			    'app/**/*.js'
			],
			legacyFilesToAppend: appFilesToAppend,
			wrapInEval: env !== 'production',
			outputFile: '/assets/app.js'
		}
	)

// Why Brendan. Why?
appjs = (env === 'production') ?
	uglifyJavaScript(appJs, {
		mangle: true,
		compress: true
	}) : appjs;