Well Isaac...I became now a little bit smarter then yesterday!!! I show you the example that I found and on which I´m working with.
File: foo.hs module Foo where foreign export ccall foo :: Int -> IO Int foo :: Int -> IO Int foo n = return (length (f n)) f :: Int -> [Int] f 0 = [] f n = n:(f (n-1)) To get the C wrapper you insert the following command: ghc -ffi -fvia-C -C foo.hs After execution you will have these following additional files: foo.hc foo.hi foo_stub.c foo_stub.h foo_stub.o What I did next was to create a file named: myfoo_c.c, where I will call the foo function (implemented in Haskell). (you can see this example on http://www.haskell.org/ghc/docs/latest/html/users_guide/ffi-ghc.html ) But the problem is to compile with gcc (must I put any flag or whatever set something) The gcc output is: myfoo_c.c:2:19: error: HsFFI.h: No such file or directory I downloaded this header file from: (I know that is not the correct way, but it was the only idea that occurs at the moment) http://www.koders.com/c/fidD0593B84C41CA71319BB079EFD0A2C80211C9337.aspx I compiled again and the following return error appears: myfoo_c.c:(.text+0x1c): undefined reference to `hs_init' myfoo_c.c:(.text+0x31): undefined reference to `foo' myfoo_c.c:(.text+0x50): undefined reference to `hs_exit' collect2: ld returned 1 exit status These functions are necessary to setup GHC runtime (see: http://www.haskell.org/ghc/docs/latest/html/users_guide/ffi-ghc.html ) What I want to know is how to compile myfoo_c.c?! Is it with GCC or GHC?! Chears, Miguel Lordelo. On Wed, Apr 16, 2008 at 9:16 PM, Isaac Dupree <[EMAIL PROTECTED]> wrote: > perhaps > > haskell: > foreign export "foo_func" foo :: Int -> IO Int > -- I forget the rest of the syntax here > > C++: > > extern "C" { > int foo_func(int i); > } > > int some_cplusplus_function() { > int bat = 3; > int blah = foo_func(bat); > return blah; > } > > > Is that all you need to do? > > > Miguel Lordelo wrote: > > > Hi all, > > > > Well...somehow I'm a beginner in Haskell. But actually my interest in > > Haskell will increase if it is possible to call a haskell function in > > C++. > > Something like GreenCard ( http://www.haskell.org/greencard/ ) > > simplifying > > the task of interfacing Haskell programs to external libraries > > (usually). > > But is there also a task to interface a foreign language with Haskell, > > but > > calling Haskell functions. Or c2hs which is an interface generator that > > simplifies the development of Haskell bindings to C libraries. > > > > I want to know this, because in my company some guys are doing some > > testing > > with Frotran and MatLab and I want to show them the power of haskell and > > the > > software which we are using is implemented in C++ (there is the reason > > to > > make Haskel -> C++). > > > > I read somewhere that the only way for C++ calling a haskell function is > > to > > create a binding between Haskell and C and from C to C++, but a easy > > "Hello > > World" example was not there. > > Unfortunatelly I couldn't found anything usefull, like an complete > > example, > > or how to compile the code from haskell to C to C++. > > > > Can sombody help me, please :P > > > > Chears, > > Miguel Lordelo. > > > > > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > Haskell-Cafe mailing list > > Haskell-Cafe@haskell.org > > http://www.haskell.org/mailman/listinfo/haskell-cafe > > > >
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