console-program-0.3.0.0: Examples/Full.hs

module Full where


-- Used modules from the console-program package.
import           System.Console.Command  (Commands,Tree(Node),Command(..),execute,showUsage,io)
import qualified System.Console.Argument as Argument

-- Standard tree type, used to build the tree of commands.
import Data.Tree (Tree(Node))


main :: IO ()
main = execute defaults myCommands

myCommands :: Commands
myCommands = Node
  (Command "count" "A program for counting" . io $ putStrLn "No command given; try \"count help\".")
  [
    Node countUp []
  , Node countDown []
  , Node help []
  ]

countUp,countDown,help :: Command
countUp = Command
  {
    name        = "up"
  , description = "Count up"
  , action      = withOption verboseOpt $ \ v -> io $ if v == Quiet
      then putStrLn "Counting quietly!"
      else mapM_ print [1 ..]
  }
countDown = Command
  {
    name        = "down"
  , description = "Count down from INT."
  , action      = withNonOption Argument.natural $ \ upperBound -> io $ mapM_ print [upperBound, pred upperBound .. 1]
  }
help = Command "help" "Show usage info" $ io (showUsage myCommands)

verboseOpt :: Option
verboseOpt = Argument.option Verbosity   ['v'] ["verbose"    ] verbosity        "Specify the verbosity of the program; "

verbosity :: Argument.Type Verbosity
verbosity = Argument.Type
  {
    Argument.parser       = \ x -> case x of
      "verbose" -> Right Verbose
      "normal"  -> Right Normal
      "quiet"   -> Right Quiet
      s         -> Left $ "The argument " ++ show s ++ " could not be recognised as a verbosity."
  , Argument.name         = "verbosity"
  , Argument.defaultValue = Just Verbose
  }