optparse-applicative instead of GetOpt

1 files changed, 31 insertions, 58 deletions

diff --git a/apps/RemovePath.hs b/apps/RemovePath.hs
index 2f73e21..d85a7f4 100644
--- a/apps/RemovePath.hs
+++ b/apps/RemovePath.hs
@@ -7,76 +7,49 @@
 module Main (main) where
 
 import Control.Monad (when)
-import System.Console.GetOpt
-import System.Environment (getArgs, getProgName)
-import System.Exit (exitFailure, exitSuccess)
-import System.IO (hPutStr, stderr)
+
+import Options.Applicative
 
 import qualified Environment
 
+data Options = Options
+    { name :: String
+    , global :: Bool
+    , paths :: [String]
+    } deriving (Eq, Show)
+
+options = Options
+    <$> nameOption
+    <*> globalOption
+    <*> pathArgs
+  where
+    nameOption = strOption $
+        long "name" <> short 'n' <> metavar "NAME" <> value "PATH" <>
+        help "Specify variable name ('PATH' by default)"
+    globalOption = switch $
+        long "global" <> short 'g' <>
+        help "Whether to remove for all users"
+    pathArgs = many $ argument str $
+        metavar "PATH" <>
+        help "Directory path(s)"
+
 main :: IO ()
-main = do
-    rawArgs <- getArgs
-    case getOpt Permute optionDescription rawArgs of
-        (actions, args, []) -> do
-            options <- foldl (>>=) (return defaultOptions) actions
-            removePath args options
-        (_, _, errorMessages) -> exitWithUsageErrors errorMessages
+main = execParser parser >>= removePath
+  where
+    parser = info (helper <*> options) $
+        fullDesc <> progDesc "Remove directories from your PATH"
 
-removePath :: [String] -> Options -> IO ()
-removePath paths options = do
+removePath :: Options -> IO ()
+removePath options = do
     let varName = name options
     userVal <- Environment.queryFromRegistry Environment.CurrentUserEnvironment varName
     let userValParts = Environment.splitPaths userVal
-    let newUserValParts = filter (`notElem` paths) userValParts
+    let newUserValParts = filter (flip notElem $ paths options) userValParts
     when (length userValParts /= length newUserValParts) $ do
         Environment.saveToRegistryWithPrompt Environment.CurrentUserEnvironment varName $ Environment.joinPaths newUserValParts
     when (global options) $ do
         globalVal <- Environment.queryFromRegistry Environment.AllUsersEnvironment varName
         let globalValParts = Environment.splitPaths globalVal
-        let newGlobalValParts = filter (`notElem` paths) globalValParts
+        let newGlobalValParts = filter (flip notElem $ paths options) globalValParts
         when (length globalValParts /= length newGlobalValParts) $ do
             Environment.saveToRegistryWithPrompt Environment.AllUsersEnvironment varName $ Environment.joinPaths newGlobalValParts
-
-data Options = Options
-    { name :: String
-    , global :: Bool
-    } deriving (Eq, Show)
-
-defaultOptions :: Options
-defaultOptions = Options
-    { name = "PATH"
-    , global = False
-    }
-
-buildHelpMessage :: IO String
-buildHelpMessage = do
-    header <- buildHeader
-    return $ usageInfo header optionDescription
-  where
-    buildHeader = do
-        progName <- getProgName
-        return $ "Usage: " ++ progName ++ " [OPTIONS...] [PATH...]\nOptions:"
-
-exitWithHelpMessage :: a -> IO b
-exitWithHelpMessage _ = do
-    helpMessage <- buildHelpMessage
-    putStr helpMessage
-    exitSuccess
-
-exitWithUsageErrors :: [String] -> IO a
-exitWithUsageErrors errorMessages = do
-    hPutStr stderr $ concatMap ("Usage error: " ++) errorMessages
-    helpMessage <- buildHelpMessage
-    hPutStr stderr helpMessage
-    exitFailure
-
-invalidNumberOfArguments :: IO a
-invalidNumberOfArguments = exitWithUsageErrors ["invalid number of arguments\n"]
-
-optionDescription :: [OptDescr (Options -> IO Options)]
-optionDescription =
-    [ Option "n" ["name"] (ReqArg (\s opts -> return opts { name = s }) "NAME") "set the variable name ('PATH' by default)"
-    , Option "g" ["global"] (NoArg $ \opts -> return opts { global = True }) "remove the path for all users"
-    , Option "h" ["help"] (NoArg exitWithHelpMessage) "show this message and exit"
-    ]