@hackage options0.1

The options package lets library and application developers easily work with command-line options.

The following example is a full program that can accept two options, --message and --quiet:

{-# LANGUAGE TemplateHaskell #-}

import Options

defineOptions "MainOptions" $ do
    stringOption "optMessage" "message" "Hello world!"
        "A message to show the user."
    boolOption "optQuiet" "quiet" False
        "Whether to be quiet."
 
main :: IO ()
main = runCommand $ \opts args -> do
    if optQuiet opts
        then return ()
        else putStrLn (optMessage opts)

$ ./hello
Hello world!
$ ./hello --message='ciao mondo'
ciao mondo
$ ./hello --quiet
$

In addition, this library will automatically create documentation options such as --help and --help-all:

$ ./hello --help
Help Options:
  -h, --help                  Show option summary.
  --help-all                  Show all help options.

Application Options:
  --message                   A message to show the user.
  --quiet                     Whether to be quiet.