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

David Thomas davidleothomas at gmail.com
Tue Jul 30 16:05:48 CEST 2013

One question is how much of a discovery/indexing role Hackage plays.  There
can be a tremendous difference in ease of obtaining a commercial license,
and a restriction for "things I can use in a proprietary project, once I
pay enough" seems like a legitimate use case.

It also has some bearing on ease of contributing changes upstream - a
project that is dual licensed will probably want well-documented transfer
of ownership; a gpl only project may not.  That said, I am less sure that
Hackage needs to be the place to call that out.
On Jul 30, 2013 2:51 AM, "Vo Minh Thu" <noteed at gmail.com> wrote:

> Well, if you are willing to grant me a GPL license when I download
> your package through Hackage, GPL is accurate.
> Again you are not providing me with another license. Obtaining a
> commercial license should be seeked through other means, perhaps by
> sending you an email. I don't think Hackage should be used for making
> adverts, but I think it would be ok to state in the description of the
> package something along the lines of "commercial licenses are
> available through example.com".
> 2013/7/30 David Sorokin <david.sorokin at gmail.com>:
> > Thanks Thu,
> >
> > I agree with you. Just I don't know what to write in the license field
> of the .cabal file: GPL or OtherLicense. The both choices seem correct to
> me and misleading at the same time.
> >
> > Cheers,
> > David
> >
> > 30.07.2013, в 12:53, Vo Minh Thu написал(а):
> >
> >> 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
> >
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