This is a Rotor to compile CoffeeScript files.
The CoffeeRotor
module provides the coffee
rotor. And this is how you call it
CoffeeRotor.coffee(files)
# This goes in the place you are configuring Rotor
import Rotor.BasicRotors
import CoffeeRotor
output_path = "priv/static/assets/app.js"
Rotor.watch :coffeescripts, ["priv/assets/javascripts/*.coffee"], fn(_changed_files, all_files)->
read_files(all_files)
|> coffee
|> concat
|> output_to(output_path)
end