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import System.Environment( getArgs )
import Data.Typeable
import qualified Control.Exception
import Fractran.Parser
import Fractran.Interpreter
data FractranException = FractranException { errString :: String }
deriving (Show, Typeable)
instance Control.Exception.Exception FractranException
usageString :: String
usageString = "Usage: fractran <program file>"
program :: IO ()
program = do
args <- getArgs
fileContents <- if (length args /= 1)
then Control.Exception.throw (FractranException usageString)
else readFile (head args)
case (parseFractran fileContents) of
Left x -> putStrLn (show x)
Right x -> putStrLn (show (fractran x))
main = Control.Exception.catch program handler
where
handler :: FractranException -> IO ()
handler err = putStrLn (errString err)
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