simple sass gulp task

gulpfile.js

'use strict';
let gulp = require('gulp');
let sass = require('gulp-sass');

let buildStyles = (src, dest) => {
	let themes = `${__dirname}/sass/themes`;  // convention is _some-theme.scss => @import 'some-theme';
	let components = `${__dirname}/sass/components`;
	
	return new Promise((resolve, reject) => {
		gulp.src(src)
			.pipe(sass({
				outputStyle: 'nested',
				sourceMapEmbed: true,
				includePaths: [ themes, components ]
			}))
			.on('error', reject)
			.pipe(gulp.dest(dest))
			.on('end', resolve);
	});
};

gulp.task('sass', [], () => {
	return buildStyles(`${__dirname}/sass/styles.scss`, `${__dirname}/dist`)
		.catch(console.error);
});

gulp.task('watch', ['sass'], () => {
	gulp.watch(`${__dirname}/sass/**/*.scss`, ['sass']);
});