and give more detailed error messages for internal error conditions.
Fixes a problem where installing a set of packages where several depended
on the same package would give us a ResolvedDependency list containing
multiple copies of that package. The DepGraph was expecting unique packages.
Resolving package deps and generating install plans needs more thought
and better specified invariants.

Added readBinaryFile for on use (uploading .tar.gz files)
Remove readURI as it was not being used.

And note problem #246 about unpacking tar files with links

Several of the general util functions in Hackage.Utils are now in the main
Cabal lib in Distribution.Simple.Utils so we use those.
The Package class moved into Distribution.Package.
Use the packageId class function in more places.

and instead of exitWith ExitSuccess just return through main rather than
throwing an exception

A naive implementation of 'cabal check'.
It will list the errors and warnings as implemented by Cabal, yielding them
in groups of severity. Currently ignores verbosity levels, no additional
arguments are understood. This addresses ticket #211.

Then print out at the end why packages failed. This is a step closer to
producing detailed build reports.

And use that to simplify the code slightly. Also add an assertion into
removeFailed, that the first returned result is the failed package itself,
since we'll rely on this in the install code.

and adapt to the minor finalisePackageDescription change

This allows us to figure out what to do when installing a single package
fails. Instead of just carrying on as if nothing had happened and then
failing several other packages which depended on the one that failed
initially we can cut those dependent packages out as soon as the first one
fails and if there is anything left that did not depend on the failed
package then we can try and carry on.

The InstalledPackageIndex replaces our Hackage.LocalIndex module

Due to recent Cabal api changes

Just like the install command has always done. This makes them consistent.
So by default that means cabal configure uses --user --prefix=$HOME/.cabal

All the other warnings are instances of ghc bug #1148.

Implements feature request #167.

To allow us to implement case-insensitivity in package names given on the
command line. We lookup in the package index for packages with the same name
case-insensitively. If there is no exact match exact case-sensitively and
there are more than one packages matching case-insensitively then it aborts
with a message listing the matches. This should not often happen since within
any single HackageDB server, we can check that packages names are unique
case-insensitively but it's possible to get ambiguities if cabal-install has
been configured to use multiple repos.

The whole Dependency module is pure now, no IO since it takes the indexes
as arguments, rather than the many more args required to do the IO to load
up the indexes. Much nicer. Also update all callers.

Added my copyright as I've almost completely rewritten the module.

Very much like the RepoIndex module but only holds package ids at the moment
 rather that full InstalledPackageInfo records that we'd really prefer.

In preperation to add Hackage.LocalIndex module

Not much faster but rather cleaner.

This represents the collection of packages from a remote repo.
It encodes the policies on how we find packages when we have multiple repos.
The policy is encoded in the repo merge operation and in the various kinds of
lookup functions.