For http://stackoverflow.com/q/18730507/457519

Gruntfile.js

module.exports = function (grunt) {
  grunt.initConfig({
    stylus: {
      compile: {
        options: {
          compress: true,
          use: [ require('bootstrap.stylus') ]
        },
        files: [{
          expand: true,
          cwd: 'public/styl',
          src: [ filepath ],
          dest: 'public/dist/css',
          ext: '.css',
        }]
      }
    },
    watch: {
      options: {
        livereload: true
      },
      stylus: {
        files: ['public/styl/**/*.styl'],
        tasks: ['stylus']
      }
    }
  });

  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.loadNpmTasks('grunt-contrib-stylus');

});