[Haskell] getopts-ab-option

getopts-ab-option.hs

module Main where
import System.Console.GetOpt
import System.Environment

data Flag = OptionA | OptionB

options :: [OptDescr Flag]
options =
  [ Option ['a']      []             (NoArg OptionA)       "Option A"
  , Option ['b']      []             (NoArg OptionB)       "Option B"
  ]


main :: IO ()
main =  do
  args <- getArgs
  case (getOpt Permute options args) of
    ([OptionA], [], []) -> print "Option A"
    ([OptionB], [], []) -> print "Option B"
    _ -> mapM_ putStrLn (lines $ usageInfo "Usage: prog [OPTION...]" options)