[darcs-devel] [patch1661] give FileUUID some love

[Guillaume Hoffmann]

Hi Ben.

beyond the topic of preparing some release, I regret that a dependency
is introduced just for one function that does not seem that central to
Darcs. I also haven't found an example of pretty-show in this
library's Readme file. So you should be the one to convince the rest
of us by providing some explanation or example.

Now, for GHC / Cabal / dependencies versions.

For a long time Darcs was very conservative: support old GHC's
versions as long as some user of it appeared and asked for us. This
lead to some releases of Darcs supporting a wide range of GHC versions
(look for it, around 2.5 or 2.8 I think).

Of course this was costly in developer effort, code quality and
overall progress. So at some point it was decided that we should
support the following sets of GHC versions:

1. the last two major GHC releases for which there exists a Haskell
Platform release.
2. every release from the last one to the one supported by Debian stable

And we wrote that down in:   http://darcs.net/Development/Policy

Or course, 2. is practically always a superset of 1.

I guess Set 2. is because we (used to?) have many Darcs users that are
also Debian users. So people using Deban Stable can compile darcs with
their current installed GHC version, something I personally was never
a fan of, since one can just download a GHC tarball and install it.

Perhaps more interestingly, Debian packages are used as the basis of
Ubuntu packages, so if you keep Debian packagers happy (by not
depending on too new Haskell libs), you will probably get Darcs
packages for Debian Testing *and* Ubuntu at a fast pace, which is what
we want because this represents many potential users. This practically
corresponds to Set 1.

So currently, Debian stable (stretch) provides GHC 8 and Cabal 1.24.
Darcs currently requires Cabal 1.22.5, which probably should be
changed ASAP. But I would definitely agree to bump some important
dependency (including GHC) if things get complicated.

Guillaume