On Tue, Jan 25, 2011 at 8:53 PM, John Millikin
<jmillikin@gmail.com> wrote:
On Tue, Jan 25, 2011 at 18:55, Chris Smith <
cdsmith@gmail.com> wrote:
> Licensing with the GPL has definite consequences; for example, that the
> great majority of Haskell libraries, which are BSD3 licensed, may not
> legitimately declare dependencies on it.
>
depend on GPL'd code.
I am not an IP lawyer, but this is my understanding of the GPL and it's transitive relationship with bodies of work that aren't GPL'd.
BSD3 doesn't really state anything about what it links with, but the GPL injects itself into the tree of stuff it's linked with via the derivative works clause. The consequence is that the entire derivative work becomes GPL'd as well, and those distributing the derivative work must adhere to the terms of the GPL for distribution and provide source.
This is somewhat in the tradition of commercial middleware requiring a royalty fee or some per-installation licensing when a work is distributed that uses a particular library with such terms. In other words transitive licensing properties are NOT unique to the GPL.
At least that's always been my understanding. A BSD3 library in isolation may still remain BSD3, but if it's not useful without being linked to a GPL'd library, then the point is kind of moot, except that someone is free to implement a replacement for the GPL'd part to avoid the transitive properties in the derivative work, in much the same way you could implement a free version of a commercial library (barring patent or other violations) to avoid transitive properties of the commercial license.
Dave
The only license Cabal allows that conflicts with the GPL is BSD4,
which (to my knowledge) is not used by any software on Hackage.