[Hackage] #578: Allow installation of distro packages

[Hackage]

#578: Allow installation of distro packages
---------------------------------+------------------------------------------
  Reporter:  bos                 |        Owner:                 
      Type:  enhancement         |       Status:  new            
  Priority:  normal              |    Milestone:  _|_            
 Component:  cabal-install tool  |      Version:                 
  Severity:  normal              |   Resolution:                 
  Keywords:                      |   Difficulty:  project(> week)
Ghcversion:                      |     Platform:                 
---------------------------------+------------------------------------------
Changes (by duncan):

  * difficulty:  unknown => project(> week)
  * version:  1.6.0.1 =>
  * milestone:  => _|_

Comment:

 I think this would be extremely difficult to do sanely and correctly.

 For one thing there's the permissions issue. It's only any good if the
 user is root so that they can install system packages. We would also need
 to know that the compiler the user is using is actually provided by a
 distro package.

 The main issue is that asking if a version of a Haskell package is
 available as a distro package is not nearly enough information for cabal-
 install to construct an installation plan.

 We do not know if the distro package provides the same thing as what our
 install plan calls for. We can ask the system-specific script if a distro
 package for foo-1.0 is available, but if the distro built foo-1.0 against
 bar-1.0 but our install plan called for it to use bar-2.0 then we're
 stuffed (or we need to replan everything and there is no guarantee that
 the alternative plan exists).

 It would need integration on a rather more intimate level. We would need
 to know the complete dependency info between the distro packages (at least
 between those providing Haskell packages). There's the added complication
 that distro packages will often bundle several Haskell packages (like ghc
 + core packages).

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/578#comment:1>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects