[patch] lincenses warning

[Francesco Ariis]

On Sun, Mar 08, 2015 at 01:19:34PM -0400, Carter Schonwald wrote:
> On Sat, Mar 7, 2015 at 3:43 PM, Francesco Ariis <fa-ml at ariis.it> wrote:
> > My view is that, with an expressive enough License datatype which covers
> > an ample portion of usages, the warning could still be pragmatically
> > useful ("do you really have a reason to draft a new document when there
> > is probably something tried and tested out there which could do for your
> > case?").
>
> there will never be an expressive enough licenses datatype. Law is
> complicated and fluid and changing. Period.

Well, I ran a little test on the index of packages [1], to check the most
popular licences there and see how widespread is the use of OtherLicense.

BSD3 5007
MIT 976
GPL 460
OtherLicense 307
GPL-3 286
PublicDomain 199
LGPL 145
GPL-2 81
Apache-2.0 53
LGPL-3 51
LGPL-2.1 49
parse-error 43
none 36
BSD2 23
AGPL-3 21
BSD3  8
BSD4 5
OtherLicense  3
Apache License, Version 2.0 3
LGPL-2 2
<Misc> 13

Parsing was extremely crude, but enough to conclude that OtherLicense
amounts to less than 4% of the total amount of packages (7771).

If we find a way to deal with dual licences and add some missing licences
to Cabal (e.g. Artistic License 2), the Licence datatype will cover
99%+ of usage, which is expressive enough in my opinion (and it's not
we cannot add more stuff as new licenses pop up).


[1] https://hackage.haskell.org/packages/index.tar.gz