[Haskell-cafe] Cabal && license combinations

[Duncan Coutts]

On Thu, 2011-02-10 at 19:00 +1300, Vivian McPhail wrote:
> > > It seems then that a package should be the least restrictive
> > > combination of all the licenses in all the contained modules.
> >
> > Omit the words "least restrictive" and I think you are correct.
> >
> > To combine licences, just aggregate them.  There is no lattice of
> > subsumption; no "more" or "less" restrictive ordering.
> >
> 
> I was thinking that the lattice was already flattened into a list of
> licences.  Currently the top-level package has a single licence field
> which is an arbitrary disjunctive choice.  Much better is a
> conjunctive aggregation which is just as or less restrictive than the
> arbitrary disjunctive choice.

Note that the license field in the .cabal specifies the license *for
that package only* not the license of dependencies, or any notion of
"effective" given the dependencies.

Each package specifies its own license, then given a dependency tree we
can calculate the set of licenses that users must simultaneously comply
with.

Duncan