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import Foreign
import Foreign.C.Types
foreign import ccall "wrapper"
mkComparator :: (Ptr Int -> Ptr Int -> IO CInt)
-> IO (FunPtr (Ptr Int -> Ptr Int -> IO CInt))
foreign import ccall
qsort :: Ptr Int -> CSize -> CSize -> FunPtr (Ptr Int -> Ptr Int -> IO CInt)
-> IO ()
compareInts :: Ptr Int -> Ptr Int -> IO CInt
compareInts a1 a2 = do
i1 <- peek a1
i2 <- peek a2
return (fromIntegral (i1 - i2 :: Int))
main :: IO ()
main = do
c <- mkComparator compareInts
let values = [ 12, 56, 90, 34, 78 ] :: [Int]
n = length values
withArray values $ \ buf -> do
qsort buf (fromIntegral n) (fromIntegral (sizeOf (head values))) c
values' <- peekArray n buf
print values'
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