build.sh

rm *.o
rm test

ghclib=$(dirname $(which ghc))/../

ghc -fPIC -static -c Foo.hs
gcc -c test.c -I$ghclib/lib/ghc-8.2.2/include
ghc -o test test.o Foo.o -no-hs-main

#executation
./test

Foo.hs

module Foo where

import Foreign.C.Types (CInt(..))
import Foreign.Ptr (Ptr,FunPtr)

func :: CInt -> CInt -> CInt
func j i = j + i+1


foreign import ccall "wrapper" mkFPtr :: (CInt -> CInt) -> IO (FunPtr (CInt -> CInt))

-- dynamic is inverse of wrapper
foreign import ccall "dynamic" mkFun :: FunPtr (CInt -> CInt) -> CInt -> CInt

foreign export ccall baz :: IO (FunPtr (CInt -> CInt))

baz :: IO (FunPtr (CInt -> CInt))
baz = do
  putStrLn "I am baz!!"
  fptr <- mkFPtr (func 20)
  pure fptr


foreign export ccall qux :: FunPtr (CInt -> CInt) -> IO ()


qux :: (FunPtr (CInt -> CInt)) -> IO () 
qux fptr =
  print $ mkFun fptr 11

test.c

#include <stdio.h>
#include "Foo_stub.h"

int main( int argc, char** argv ) {
  hs_init( &argc, &argv );
  
  int(*f)(int);

  f = baz();

  // C side call
  int r = f(1);

  printf("r = %d\n",r);

  // Haskell side call
  qux(f);
  
}