old_contents: from redux.codegenerator import compile_script
  from argparse import ArgumentParser
  from os.path import splitext
  
  parser = ArgumentParser(description='Compile a Redux script to Rescript.')
  parser.add_argument('filenames', metavar='FILE', nargs='+',
                      help='script to be compiled to Rescript')
  
  args = parser.parse_args()
  
  for filename in args.filenames:
      with open(filename, "rt") as file_:
          input_code = file_.read()
  
      base_filename, extension = splitext(filename)
      with open(base_filename + ".ais", "wt") as file_:
          file_.write(compile_script(filename, input_code))
  
new_contents: from redux.codegenerator import compile_script
  from argparse import ArgumentParser
  from os.path import splitext
  
  parser = ArgumentParser(description='Compile a Redux script to Rescript.')
  parser.add_argument('input_filename', metavar='FILE',
                      help='script to be compiled to Rescript')
  parser.add_argument('output_filename', metavar='FILE',
                      help='script to be compiled to Rescript')
  
  args = parser.parse_args()
  
  filename = args.input_filename
  assert filename, "no input file given"
  
  with open(filename, "rt") as file_:
      input_code = file_.read()
  
  output_code = compile_script(filename, input_code)
  
  base_filename, extension = splitext(filename)
  with open(args.output_filename, "wt") as file_:
      file_.write(output_code)
  
subject: Make compiler invocation more Makefile-friendly