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|
{-# LANGUAGE DeriveDataTypeable
, ForeignFunctionInterface #-}
-- Copyright (c) 2014, Sven Bartscher
-- Look the file LICENSE.txt in the toplevel directory of the source tree for
-- more information.
module System.Locale.SetLocale ( Category(..)
, categoryToCInt
, setLocale
)
where
#include <locale.h>
import Data.Typeable
import Data.Maybe
import Foreign.C
import Foreign.Ptr
data Category = LC_ALL
| LC_COLLATE
| LC_CTYPE
| LC_MESSAGES
| LC_MONETARY
| LC_NUMERIC
| LC_TIME
deriving (Bounded, Enum, Eq, Ord, Read, Show, Typeable)
categoryToCInt :: Category -> CInt
categoryToCInt LC_ALL = #const LC_ALL
categoryToCInt LC_COLLATE = #const LC_COLLATE
categoryToCInt LC_CTYPE = #const LC_CTYPE
categoryToCInt LC_MESSAGES = #const LC_MESSAGES
categoryToCInt LC_MONETARY = #const LC_MONETARY
categoryToCInt LC_NUMERIC = #const LC_NUMERIC
categoryToCInt LC_TIME = #const LC_TIME
foreign import ccall "locale.h setlocale" c_setlocale :: CInt -> CString -> IO (CString)
setLocale :: Category -> Maybe String -> IO (Maybe String)
setLocale c Nothing = c_setlocale (categoryToCInt c) nullPtr >>= checkReturn
setLocale c (Just locale) = (withCString locale $ c_setlocale $ categoryToCInt c)
>>= checkReturn
checkReturn :: CString -> IO (Maybe String)
checkReturn r
| r == nullPtr = return Nothing
| otherwise = fmap Just $ peekCString r
|
