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|
-----------------------------------------------------------------------------
-- Standard Library: System operations
--
-- Warning: the implementation of these functions in Hugs 1.4 is very weak.
-- The functions themselves are best suited to uses in compiled programs,
-- and not to use in an interpreter-based environment like Hugs.
--
-- Suitable for use with Hugs 1.4.
-----------------------------------------------------------------------------
module System (
ExitCode(..), exitWith,
getArgs, getProgName, getEnv,
system
) where
data ExitCode = ExitSuccess | ExitFailure Int
deriving (Eq, Ord, Read, Show)
primitive primArgc :: IO Int
primitive primArgv :: Int -> IO String
getArgs :: IO [String]
getArgs = do argc <- primArgc
mapM primArgv [1..argc-1]
getProgName :: IO String
getProgName = primArgv 0
primitive getEnv :: String -> IO String
system :: String -> IO ExitCode
system s = do r <- primSystem s
return (toExitCode r)
exitWith :: ExitCode -> IO a
exitWith c = primExitWith (fromExitCode c)
primitive primSystem :: String -> IO Int
toExitCode :: Int -> ExitCode
toExitCode 0 = ExitSuccess
toExitCode n = ExitFailure n
fromExitCode :: ExitCode -> Int
fromExitCode ExitSuccess = 0
fromExitCode (ExitFailure n) = n
-----------------------------------------------------------------------------
|
