[Haskell-cafe] Mystified by Cabal

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Tue Mar 10 06:00:24 EDT 2009

On Mon, 2009-03-09 at 17:56 -0700, John Meacham wrote:
> On Sun, Mar 08, 2009 at 01:13:33PM +0100, Svein Ove Aas wrote:
> > On Sun, Mar 8, 2009 at 12:32 PM, Duncan Coutts
> > <duncan.coutts at worc.ox.ac.uk> wrote:
> > > Note also that the list of licenses mkcabal offers is wrong. You can get
> > > the list from the Cabal lib itself so there is no need to maintain the
> > > list manually.
> > >
> > It would also be nice to expand that list somewhat, to at least cover
> > the most used licences - GPL2, GPL3, AGPL, etc.
> Why would cabal need a list at all inside of it? It seems very odd to
> have to upgrade cabal just because I am using a different license.
> it seems that we should just bite the bullet and switch data License to 
> newtype License = License String
> and simplify a lot of code to boot as well as create a normalized data
> layout.

Because it was not that way initially and changing away to something
more sensible takes time so that we do not cause unnecessary breakage.

Now it does allow any string at all. There are however a list of "well
known" licenses and the point of that is so that we can collectively use
the same name for the same thing. There's nothing however stopping you
from using a custom license. At the moment you cannot give a name in
the .cabal file to that custom license and upload it to hackage and I
think that's what you're getting at. If everyone agrees that's the way
to go then we can certainly change it.

The hard part was phasing out the fragile parser. We are now half way
through that cycle. When we no longer care about users of ghc-6.8 then
we can make use of the extra flexibility.


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