[Haskell-cafe] foreign function interface "Invalid type signature"

[Ken Takusagawa]

What am I doing wrong?

module Ffi2 where
{
import Foreign.C.Types;

foo :: CInt -> CInt;
foo x = x;

foreign export ccall foo :: CInt -> CInt;

}

$ ghc -c Ffi2.hs

Ffi2.hs:8:0: Invalid type signature

--ken