All code included into generated bindings is under a BSD-style license that does not place any restrictions on the license of the inteface produced with C->Haskell (ie, closed proprietary licenses are possible, too). In other words, I do not care what you use C->Haskell for or to whom you are giving C->Haskell or any interfaces generated with C->Haskell, only if you modify or improve C->Haskell itself, you have to contribute your changes back to the community. Nevertheless, I will of course be particularly delighted if you choose to make your work freely available.