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blog-meta/lib/Misc.hs

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+module Misc where
+
+import qualified System.Console.GetOpt as GetOpt
+import System.Environment
+import System.Exit
+
+-- | exception on 'Left'
+unwrap :: Show a => FilePath -> Either a b -> IO b
+unwrap file = either (\x -> fail $ file <> ":" <> show x) return
+
+getOptionsWith :: (String -> String) -> ([String] -> Maybe a)
+               -> [GetOpt.OptDescr (a -> a)] -> IO a
+getOptionsWith hdr mkDef descrs = do
+  res <- GetOpt.getOpt GetOpt.Permute descrs <$> getArgs
+  case res of
+    (fs, rest, []) | Just def <- mkDef rest ->
+      return $ foldl (flip ($)) def fs
+    _ -> do
+      prog <- getProgName
+      putStrLn $ GetOpt.usageInfo (hdr prog) descrs
+      exitFailure
+