FFI and GHC

[Hal Daume III]

Two things.  First, you need a module name.  So prefix your code with
'module Foo where'.  Secondly, the call to ghc needs -fglasgow-exts to
pick up the necessary extensions.

--
Hal Daume III

 "Computer science is no more about computers    | hdaume@isi.edu
  than astronomy is about telescopes." -Dijkstra | www.isi.edu/~hdaume

On 19 Oct 2002, [ISO-8859-1] Jo=E3o Ferreira wrote:

> Hello all,
>=20
> I am trying to learn how to use FFI with GHC. I've tried the example in
> GHC's user's guide but it didn't worked. Here it is:
>=20
>=20
> 1) The haskell code
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>=20
> [bracaman@tucano hib]$ cat foo.hs
> foreign export ccall foo :: Int -> IO Int
>=20
> foo :: Int -> IO Int
> foo n =3D return (length (f n))
>=20
> f :: Int -> [Int]
> f 0 =3D []
> f n =3D n:(f (n-1))
>=20
> 2) The error
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>=20
> [bracaman@tucano hib]$ ghc -c foo.hs
> foo.hs:3: Type signature given for an expression
> [bracaman@tucano hib]$
>=20
>=20
> I just can't understand why this is happening... can someone, please,
> help?
>=20
> Thank you in advance,
> Jo=E3o Ferreira
>=20
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>=20