add cli for usage-example

cli-example/Main.hs

@@ -0,0 +1,52 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Main where
+
+import MDict
+import System.Environment (getArgs)
+import System.IO (hSetBuffering, stdout, BufferMode(..))
+import Control.Exception (try, SomeException)
+import Control.Monad (unless)
+import System.Exit (exitSuccess)
+
+-- Highest Priority: Safe dictionary initialization with error handling
+loadDictionary :: FilePath -> IO (Either String MDict)
+loadDictionary path = do
+  result <- try $ withMDict path (return . Right) 
+  case result of
+    Left (e :: SomeException) -> return $ Left $ "Error loading dictionary: " ++ show e
+    Right dict -> return dict
+
+-- Medium Priority: Interactive lookup loop with graceful exit
+lookupLoop :: MDict -> IO ()
+lookupLoop dict = do
+  putStr "Enter word to lookup (or :quit to exit): "
+  hSetBuffering stdout NoBuffering
+  input <- getLine
+  unless (input == ":quit") $ do
+    result <- lookupWord dict input
+    case result of
+      Just definition -> putStrLn $ "\nDefinition:\n" ++ definition ++ "\n"
+      Nothing -> putStrLn $ "\n'" ++ input ++ "' not found in dictionary.\n"
+    lookupLoop dict
+  putStrLn "Exiting..."
+  exitSuccess
+
+-- Critical: Command-line argument validation
+main :: IO ()
+main = do
+  hSetBuffering stdout NoBuffering
+  args <- getArgs
+  case args of
+    [mdxPath] -> do
+      putStrLn $ "Loading dictionary: " ++ mdxPath
+      eitherDict <- loadDictionary mdxPath
+      case eitherDict of
+        Left err -> putStrLn err
+        Right dict -> do
+          putStrLn "Dictionary loaded successfully!\n"
+          lookupLoop dict
+    _ -> putStrLn $ unlines
+      [ "Invalid arguments!"
+      , "Usage: mdict-lookup <path-to-mdict.mdx>"
+      , "Example: mdict-lookup /dictionaries/cantonese.mdx"
+      ]