I'm experimenting with the haskell FFI, and have run into a odd little
problem. For some reason, ghc won't let me import functions with no
arguments...
Here's my C file (hw.c)
#include <stdio.h>
void hiworld(void)
{
printf("Hello, haskell world!\n");
}
Compiled to a shared library with
$ gcc --shared -c -o hw.so hw.c
And my first try (for.hs)
foreign import ccall "hiworld.so" "hiworld" hiworld :: () -> IO ()
main = hiworld ()
and I get:
$ ghc for.hs hw.so -fglasgow-exts
for.hs:5:
Unacceptable argument type in foreign declaration: ()
When checking declaration:
foreign import _ccall "hiworld.so" "hiworld" hiworld :: () -> IO
()
Alright then, so I tried something else:
foreign import ccall "hiworld.so" "hiworld" hiworld :: IO () -> IO ()
main = hiworld ()
gets
for.hs:5:
Unacceptable argument type in foreign declaration: IO ()
When checking declaration:
foreign import _ccall "hiworld.so" "hiworld" hiworld :: IO ()
-> IO ()
for.hs:7:
Couldn't match `IO ()' against `()'
Expected type: IO ()
Inferred type: ()
In the first argument of `hiworld', namely `()'
In the right-hand side of a pattern binding: hiworld ()
Could someone help me with the right syntax here?
------------------ Peter Amstutz --------------------
-------------- [EMAIL PROTECTED] -------------
------- http://www-unix.oit.umass.edu/~tetron -------
-----------------------------------------------------
