[Haskell-cafe] Re: GPL answers from the SFLC

The next question that comes to mind is thus: What if a new library X' released under BSD or MIT license implements the X API (making possible to compile Y against it)? Can such a new library X' be licensed under something else than the GPL (we guess Yes because we don't think it is possible to license the API itself)?

Yes.

Why should the existence of X' make any difference for the author of Y?

Because the existence of X' makes it possible to use Y without using X. The order in which X and X' come to exist doesn't matter. This exact scenario took place for the GMP library, whose API was reimplemented as fgmp, specifically so that a user of the GMP library could release their code under a different library than the GPL. Stefan