v1 perplexed

app/Main.hs

@@ -0,0 +1,57 @@
+module Main where
+
+import System.Environment (getArgs)
+import System.Exit (exitFailure, exitSuccess)
+import System.IO (hPutStrLn, stderr)
+
+import FWL.Parser  (parseFile)
+import FWL.Pretty  (prettyProgram)
+import FWL.Check   (checkProgram)
+import FWL.Compile (compileToJson, compileProgram)
+
+main :: IO ()
+main = do
+  args <- getArgs
+  case args of
+    ["check",  fp] -> runCheck fp
+    ["compile", fp] -> runCompile fp
+    ["pretty",  fp] -> runPretty fp
+    _ -> do
+      putStrLn "Usage: fwlc <command> <file.fwl>"
+      putStrLn "  check   <file>   -- parse and static-check"
+      putStrLn "  compile <file>   -- emit nftables JSON to stdout"
+      putStrLn "  pretty  <file>   -- parse and re-print"
+      exitFailure
+
+runCheck :: FilePath -> IO ()
+runCheck fp = do
+  result <- parseFile fp
+  case result of
+    Left err -> hPutStrLn stderr ("Parse error:\n" ++ show err) >> exitFailure
+    Right prog -> do
+      let errs = checkProgram prog
+      if null errs
+        then putStrLn "OK" >> exitSuccess
+        else do
+          mapM_ (hPutStrLn stderr . show) errs
+          exitFailure
+
+runCompile :: FilePath -> IO ()
+runCompile fp = do
+  result <- parseFile fp
+  case result of
+    Left err -> hPutStrLn stderr ("Parse error:\n" ++ show err) >> exitFailure
+    Right prog -> do
+      let errs = checkProgram prog
+      if null errs
+        then putStrLn (compileToJson prog)
+        else do
+          mapM_ (hPutStrLn stderr . ("Check error: " ++) . show) errs
+          exitFailure
+
+runPretty :: FilePath -> IO ()
+runPretty fp = do
+  result <- parseFile fp
+  case result of
+    Left err -> hPutStrLn stderr ("Parse error:\n" ++ show err) >> exitFailure
+    Right prog -> putStr (prettyProgram prog)