[Haskell-cafe] Re: ANN: hakyll-0.1

Tom Tobin korpios at korpios.com
Tue Dec 8 19:21:20 EST 2009

On Tue, Dec 8, 2009 at 6:10 PM, Erik de Castro Lopo
<mle+hs at mega-nerd.com> wrote:
> Tom Tobin wrote:
>> The background situation: X is a library distributed under the GPL.  Y
>> is another library that uses that library and requires it in order to
>> compile and function.
> You probably also need to bring in application Z which uses library
> X via library Y, because library Y is not usable by itself.

I think this is implicit in calling something a library; are there any
questions where it would come up?

>> 1) Is there any scenario where Y can be distributed under a non-GPL
>> license (e.g., the BSD)?
> You need to make sure they know that your are talking about the 3 clause
> BSD license, the one the FSF calls the Modified BSD license.

Good point.

>> 3) If Y must be released under the GPL under the above scenario, and
>> someone subsequently wrote library Z, an API compatible replacement
>> for X, and released it under the BSD license, would Y's author now be
>> permitted to release Y under the BSD?
> The author is always allowed to relicense their own work under whatever
> license they choose.

Well I think that's actually what we're wondering here — under what
circumstances is Y's author permitted to choose his license at will?

> For instance there are libraries released under
> the GPL which are also available under a commercial use license for
> use in closed source products. The requirement here is that the library
> is soley written by the person doing the dual licensing and/or all other
> contributors have assigned their rights.

But those libraries don't, in turn, depend on GPL'd libraries written
by different authors.  I think the answer to the "can Y's author
choose the BSD3 for Y" question will also answer this for cases where
there's a further, different-author GPL dependency involved.

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