sample gruntfile for coffee only

Gruntfile-coffee.coffee

"use strict"
module.exports = (grunt) ->

  # load all grunt tasks
  require("matchdep").filterDev("grunt-*").forEach grunt.loadNpmTasks

  # config
  grunt.initConfig

    watch:
      options:
        spawn: false

      coffee:
        files: ["public/javascripts/**/*.coffee"]
        tasks: ["coffee"]

    # compiles all coffeescript 1 to 1
    coffee:
      dev:
        options:
          sourceMap: true
        expand: true
        cwd: "public/javascripts"
        src: "**/*.coffee"
        dest: "public/javascripts"
        ext: ".js"

  # Tasks
  grunt.registerTask('default', ['watch'])