[GHC] #10622: Rename Backpack packages to units

[GHC]

#10622: Rename Backpack packages to units
-------------------------------------+-------------------------------------
        Reporter:  ezyang            |                   Owner:  ezyang
            Type:  task              |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:  backpack
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:  Phab:D1057
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Comment (by ezyang):

 Here is a counter-proposal, organized around avoiding changing the package
 database format:

 Cabal already has limited support for multiple "packages" in a
 distribution unit, namely with its support for testing libraries.  These
 libraries are never installed for other users to use, but internally, they
 can be installed and used like extra libraries. In this model, the
 database has a separate entry for each unit.

 The downside is that the package database will no longer be organized by
 distribution units. But this was already the case: if I install a package
 multiple times with different dependencies, it will occur multiple times
 in the database.

 The big upside is that the changes we have to make are now much smaller.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10622#comment:5>
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