[Haskell-cafe] Dual-licensing the package on Hackage

[Vo Minh Thu]

2013/7/30 David Sorokin <david.sorokin at gmail.com>:
> Hi, Cafe!
>
> Probably, it was asked before but I could not find an answer with help of Google.
>
> I have a library which is hosted on Hackage. The library is licensed under BSD3. It is a very specialized library for a small target group. Now I'm going to relicense it and release a new version already under the dual-license: GPLv3 and commercial. In most cases GPL will be sufficient as this is not a library in common sense.
>
> Can I specify the GPL license in the .cabal file, or should I write OtherLicense?
>
> I'm going to add the information about dual-licensing in the description section of the .cabal file, though.

Although you can indeed license your software under different
licences, in the case of your question it doesn't seem to be a concern
with Hackage:

The license displayed on Hackage is the one for the corresponding
.cabal file (or at least I think it is). So you issue your new version
with the changed license, the new version is available with the new
license, the old versions are still available with the old license.
Everything is fine.

Now about the dual licensing. It seems it is again not a problem with
Hackage: you are not granting through Hackage such a commercial
license. I guess you provide it upon request (for some money). I.e.
when I download your library from Hackage, I receive it under the
terms of the BSD (or GPL) license you have chosen, not under a
commercial license that I would have to receive through other means.

Otherwise the semantic of the license field on Hackage would mean the
library is available under such and such licenses, which are not
granted to you when you download the library on Hackage. Only when you
download the package you can actually find the licensing terms (e.g.
in the LICENSE file). But this seems unlikely to me.

Cheers,
Thu