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module Utils where
import System.Exit
import System.IO
import Text.Regex.Posix
die :: Errors -> IO a
die errs = do mapM_ (hPutStrLn stderr) errs
exitFailure
dieOnErrors :: Either Errors a -> IO a
dieOnErrors (Left errs) = die errs
dieOnErrors (Right x) = return x
type Errors = [String]
maybeRead :: Read a => String -> Maybe a
maybeRead str = case reads str of
[(x, "")] -> Just x
_ -> Nothing
re :: String -> String -> Maybe [String]
re r str = case matchM r' str :: Maybe (String, String, String, [String]) of
Just (_, _, _, ms) -> Just ms
Nothing -> Nothing
where r' = makeRegex r :: Regex
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