Adding a world file to cabal-install

[Peter Robinson]

2009/2/8 Duncan Coutts <duncan.coutts at worc.ox.ac.uk>:
> Another alternative is to not treat it like a meta-package and instead
> of adding the world meta-package to the list of packages to resolve for,
> we add all the world entries to the list instead. So it would be
> equivalent to:
>
> $ cabal install $(cat ./world.list)

I think that alternative is probably the easiest/cleanest. So essentially,
before calling installWithPlanner we need to check if "world" is in the
UnresolvedDeps list and, if so, replace it with the list of packages
from the world file.

I suppose this will also require a check in
hackage-scripts/Unpack.unpackPackage to prevent uploading a package
called "world".

About IO errors when updating the world file:
At the moment they are considered as non-fatal (ie. printed by chattyTry),
is that ok?

Peter