I'm a beginner at haskell and ffi. I was trying to import and use is
haskell
one C function, but I can't manage to do that.
Can someone show me an example how to create an import and a use
example for
such a C function:
char functionName(char *, unsigned int, char *)
{-# LANGUAGE ForeignFunctionInterface #-}
module FOo where
import Foreign
import Foreign.C
import Data.Word
foreign import ccall "functionName" functionName_inC
:: CString -> Word -> CString -> IO CChar
-- Assuming you really want to use Haskell Strings and Ints etc
-- and furthermore if the C function is really pure,
-- add the following wrapper.
functionName_h :: String -> Int -> String -> Char
functionName_h s0 i s1 =
unsafePerformIO $
withCString s0 $ \cs0->
withCString s1 $ \cs1->
do cchar <- functionName_inC cs0 (fromIntegral i) cs1
return (castCCharToChar cchar)
Regards,
Malcolm
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