1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
|
-----------------------------------------------------------------------------
-- Standard Library: System operations
--
-- Warning: the implementation of these functions in Hugs 98 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 98
-----------------------------------------------------------------------------
module System (
ExitCode(..), exitWith, exitFailure,
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)
exitFailure :: IO a
exitFailure = exitWith (ExitFailure 1)
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
-----------------------------------------------------------------------------
|
