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

Erik de Castro Lopo mle+hs at mega-nerd.com
Tue Dec 8 19:10:43 EST 2009

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.

> 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.

> 2) If so, what would Y's author need to do (or *not* do)?
> 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. 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.

Erik de Castro Lopo

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