optparse-applicative-0.8.0: tests/Examples/Commands.hs

{-# LANGUAGE CPP #-}
module Examples.Commands where

import Data.List
import Options.Applicative

#if __GLASGOW_HASKELL__ <= 702
import Data.Monoid
(<>) :: Monoid a => a -> a -> a
(<>) = mappend
#endif

data Sample
  = Hello [String]
  | Goodbye
  deriving Show

hello :: Parser Sample
hello = Hello <$> many (argument str (metavar "TARGET..."))

sample :: Parser Sample
sample = subparser
       ( command "hello"
         (info hello
               (progDesc "Print greeting"))
      <> command "goodbye"
         (info (pure Goodbye)
               (progDesc "Say goodbye"))
       )

run :: Sample -> IO ()
run (Hello targets) = putStrLn $ "Hello, " ++ intercalate ", " targets ++ "!"
run Goodbye = putStrLn "Goodbye."

opts :: ParserInfo Sample
opts = info (sample <**> helper) idm

main :: IO ()
main = execParser opts >>= run