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documentation:
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------------------------------------------------------------------------------
--- Library to access parts of the system environment.
---
--- @author Michael Hanus, Bernd Brassel, Bjoern Peemoeller
--- @version November 2020
--- @category general
------------------------------------------------------------------------------
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sourcecode:
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module System.Environment
( getArgs, getEnv, setEnv, unsetEnv, getProgName
, getHostname, isPosix, isWindows
) where
--- Returns the list of the program's command line arguments.
--- The program name is not included.
getArgs :: IO [String]
getArgs external
--- Returns the value of an environment variable.
--- The empty string is returned for undefined environment variables.
getEnv :: String -> IO String
getEnv evar = prim_getEnviron $## evar
prim_getEnviron :: String -> IO String
prim_getEnviron external
--- Set an environment variable to a value.
--- The new value will be passed to subsequent shell commands
--- (see <code>system</code>) and visible to subsequent calls to
--- <code>getEnv</code> (but it is not visible in the environment
--- of the process that started the program execution).
setEnv :: String -> String -> IO ()
setEnv evar val = (prim_setEnviron $## evar) $## val
prim_setEnviron :: String -> String -> IO ()
prim_setEnviron external
--- Removes an environment variable that has been set by
--- <code>setEnv</code>.
unsetEnv :: String -> IO ()
unsetEnv evar = prim_unsetEnviron $## evar
prim_unsetEnviron :: String -> IO ()
prim_unsetEnviron external
--- Returns the hostname of the machine running this process.
getHostname :: IO String
getHostname external
--- Returns the name of the current program, i.e., the name of the
--- main module currently executed.
getProgName :: IO String
getProgName external
--- Is the underlying operating system a POSIX system (unix, MacOS)?
isPosix :: Bool
isPosix = not isWindows
--- Is the underlying operating system a Windows system?
isWindows :: Bool
isWindows external
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