Example gulpfile.js

gulpfile.js

// Load plugins
var gulp = require('gulp'),
    sass = require('gulp-ruby-sass'),
    autoprefixer = require('gulp-autoprefixer'),
    minifycss = require('gulp-minify-css'),
    jshint = require('gulp-jshint'),
    uglify = require('gulp-uglify'),
    imagemin = require('gulp-imagemin'),
    rename = require('gulp-rename'),
    clean = require('gulp-clean'),
    concat = require('gulp-concat'),
    notify = require('gulp-notify'),
    cache = require('gulp-cache'),
    livereload = require('gulp-livereload'),
    lr = require('tiny-lr'),
    server = lr();

// Styles
gulp.task('styles', function() {
  return gulp.src('src/styles/main.scss')
    .pipe(sass({ style: 'expanded', }))
    .pipe(autoprefixer('last 2 version', 'safari 5', 'ie 8', 'ie 9', 'opera 12.1', 'ios 6', 'android 4'))
    .pipe(gulp.dest('dist/styles'))
    .pipe(rename({ suffix: '.min' }))
    .pipe(minifycss())
    .pipe(livereload(server))
    .pipe(gulp.dest('dist/styles'))
    .pipe(notify({ message: 'Styles task complete' }));
});

// Scripts
gulp.task('scripts', function() {
  return gulp.src('src/scripts/**/*.js')
    .pipe(jshint('.jshintrc'))
    .pipe(jshint.reporter('default'))
    .pipe(concat('main.js'))
    .pipe(gulp.dest('dist/scripts'))
    .pipe(rename({ suffix: '.min' }))
    .pipe(uglify())
    .pipe(livereload(server))
    .pipe(gulp.dest('dist/scripts'))
    .pipe(notify({ message: 'Scripts task complete' }));
});

// Images
gulp.task('images', function() {
  return gulp.src('src/images/**/*')
    .pipe(cache(imagemin({ optimizationLevel: 3, progressive: true, interlaced: true })))
    .pipe(livereload(server))
    .pipe(gulp.dest('dist/images'))
    .pipe(notify({ message: 'Images task complete' }));
});

// Clean
gulp.task('clean', function() {
  return gulp.src(['dist/styles', 'dist/scripts', 'dist/images'], {read: false})
    .pipe(clean());
});

// Default task
gulp.task('default', ['clean'], function() {
    gulp.run('styles', 'scripts', 'images');
});

// Watch
gulp.task('watch', function() {

  // Listen on port 35729
  server.listen(35729, function (err) {
    if (err) {
      return console.log(err)
    };

    // Watch .scss files
    gulp.watch('src/styles/**/*.scss', function(event) {
      console.log('File ' + event.path + ' was ' + event.type + ', running tasks...');
      gulp.run('styles');
    });

    // Watch .js files
    gulp.watch('src/scripts/**/*.js', function(event) {
      console.log('File ' + event.path + ' was ' + event.type + ', running tasks...');
      gulp.run('scripts');
    });

    // Watch image files
    gulp.watch('src/images/**/*', function(event) {
      console.log('File ' + event.path + ' was ' + event.type + ', running tasks...');
      gulp.run('images');
    });

  });

});

Hello @brunocassol,
(assuming you mean the 'styles' gulp task)
It is telling to write out the current stream to that destination so in the first part it is compiling the sass and adding autoprefix then writing the result of those two. After that it minifies the css and writes it out again to the destination.

Nice ..handy code just plug it and use.

Does this code work well with gulp V4 ?