aavogt · August 29, 2015 14:05
diff --git a/a.c b/a.c
 double f (double x) {
  return (x*2);
 }
diff --git a/a.h b/a.h
 double f (double x);
diff --git a/main.hs b/main.hs
 {-# LANGUAGE ForeignFunctionInterface #-}
 foreign import ccall "a.h f" f :: Int -> Int
 main = print (f 3)
 {-
 ghc a.h a.c main.hs
 ./main
 130560

 prints 6.0 if you give f :: Double -> Double

 -}
	{-# LANGUAGE ForeignFunctionInterface #-}
	foreign import ccall "a.h f" f :: Int -> Int
	main = print (f 3)
	{-
	ghc a.h a.c main.hs
	./main
	130560

	prints 6.0 if you give f :: Double -> Double

	-}